Global Technical Regulation No. 13

Name:Global Technical Regulation No. 13
Description:Hydrogen and Fuel Cell Vehicles.
Official Title:Global Technical Regulation on Hydrogen and Fuel Cell Vehicles.
Country:ECE - United Nations
Date of Issue:2013-06-27
Amendment Level:Amendment 1 of July 17, 2023
Number of Pages:194
Vehicle Types:Bus, Car, Component, Heavy Truck, Light Truck
Subject Categories:Electrical and Electronic, Miscellaneous
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Keywords:

test, hydrogen, pressure, paragraph, container, system, vehicle, temperature, fuel, burner, requirements, storage, fire, vehicles, chss, gas, fuelling, nwp, tests, testing, engulfing, maximum, conditions, containers, service, valve, leak, cycles, compressed, localized, burst, systems, leakage, performance, figure, time, tprd, rate, procedure, rationale, materials, air, minimum, flow, qualification, table, helium, exposure, data, pre-test

Text Extract:

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ECE/TRANS/180/Add.13/Amend.1
July 17, 2023
GLOBAL REGISTRY
Created on November 18, 2004, Pursuant to Article 6 of the
AGREEMENT CONCERNING THE ESTABLISHING OF GLOBAL TECHNICAL
REGULATIONS FOR WHEELED VEHICLES, EQUIPMENT AND PARTS WHICH
CAN BE FITTED AND/OR BE USED ON WHEELED VEHICLES
(ECE/TRANS/132 and Corr.1)
DONE AT GENEVA ON JUNE 25, 1998
Addendum 13:
GLOBAL TECHNICAL REGULATION NO. 13
GLOBAL TECHNICAL REGULATION ON HYDROGEN AND FUEL CELL VEHICLES
(ESTABLISHED IN THE GLOBAL REGISTRY ON JUNE 27, 2013)
Incorporating:
Amendment 1 dated July 17, 2023

G. Optional Requirements: Vehicles with Liquefied Hydrogen Storage Systems/Rationale
1. Background Information for Liquefied Hydrogen Storage Systems
2. Rationale for Liquefied Hydrogen Storage System Design Qualification Requirements
of Paragraph 7.2.
3. Rationale for Vehicle Fuel System Design Qualification Requirements (LH )
4. Rationale for Test Procedures for LHSSs
5. Rationale for Paragraph 7.5. (Test Procedure for Post-crash Concentration
Measurement for Vehicles with Liquefied Hydrogen Storage Systems)
H. National Provisions for Material Compatibility (Including Hydrogen Embrittlement) and
Conformity of Production
1. Material Compatibility and Hydrogen Embrittlement
2. National Requirements Complimentary to UN GTR Requirements
I. Topics for the Next Phase in Developing the UN GTR for Hydrogen-fuelled Vehicles
J. Existing Regulations, Directives, and International Standards
1. Vehicle Fuel System Integrity
2. Storage System
K. Benefits and Costs
L. Interoperability Considerations
1. Principal Interoperability Elements
2. Description of SAE J2601
3. Use of Vehicle-to-Station Communication
4. Validation of the Fuelling Protocol and Vehicle-to-Station Communication
M. Materials Evaluation for Hydrogen Service
1. Introduction
2. Rationale for Material Definitions (Paragraph 220)
3. Rationale for Environmental Test Condition (Paragraph 221)
4. Rationale for Testing Requirements (Paragraph 222)
5. Test Procedure

GLOBAL TECHNICAL REGULATION NO. 13
I. STATEMENT OF TECHNICAL RATIONALE AND JUSTIFICATION
A. INTRODUCTION
1. In the ongoing debate over the need to identify new sources of energy and to reduce
greenhouse gas emissions, companies around the world have explored the use of various
alternative fuels, including compressed natural gas, liquefied propane gas and hydrogen.
Hydrogen has emerged as one of the most promising alternatives due to its vehicle emissions
being virtually zero. In the late 1990s, the European Community allocated resources to study
the issue under its European Integrated Hydrogen Project (EIHP) and forwarded the results,
two proposals for compressed gaseous and liquefied hydrogen, to the ECE secretariat. The
follow-up project, EIHP2, initiated discussions about the possibility of a global technical
regulation for hydrogen fuelled vehicles. A few years later, the United States of America
outlined a vision for a global initiative, the International Partnership for the Hydrogen
Economy, and invited China, Japan, the Russian Federation, the European Union and many
other countries to participate in this effort.
2. For decades scientists, researchers and economists have pointed to hydrogen, in both
compressed gaseous and liquid forms, as a possible alternative to gasoline and diesel as a
vehicle fuel. Ensuring the safe use of hydrogen as a fuel is a critical element in successful
transitioning to a global hydrogen economy. By their nature, all fuels present an inherent
degree of danger due to their energy content. The safe use of hydrogen, particularly in the
compressed gaseous form, lies in preventing catastrophic failures involving a combination of
fuel, air and ignition sources as well as pressure and electrical hazards.
3. Governments have identified the development of regulations and standards as one of the key
requirements for commercialization of hydrogen-fuelled vehicles. Regulations and standards
will help overcome technological barriers to commercialization, facilitate manufacturers'
investment in building hydrogen-fuelled vehicles and facilitate public acceptance by providing
a systematic and accurate means of assessing and communicating the risk associated with
the use of hydrogen vehicles, be it to the general public, consumer, emergency response
personnel or the insurance industry.
4. The development of this United Nations Global Technical Regulation (UN GTR) for Hydrogen
and Fuel Cell Vehicles occurred within the World Forum for Harmonisation of Vehicle
Regulations (WP.29) of the Inland Transport Committee (ITC) of ECE. The goals of this global
technical regulation (UN GTR) are to develop and establish a UN GTR for hydrogen-fuelled
vehicles that:
(i)
(ii)
attains or exceeds the equivalent levels of safety of those for conventional gasoline
fuelled vehicles; and
is performance-based and does not restrict future technologies.
5. On June 27, 2013, UN GTR No. 13, (ECE/TRANS/180/Add.13) was established under the
sponsorship of Germany, Japan and the United States of America. UN GTR 13 applies to all
hydrogen-fuelled vehicles of Categories 1-1 and 1-2, with a gross vehicle mass (GVM) of
4,536kg or less. UN GTR No. 13 consists of three main sections: high voltage system,
hydrogen storage system and hydrogen fuel system at vehicle level. The UN GTR provides
provisions for in-use and post-crash scenarios.

9. In order to develop the UN GTR in the context of evolving hydrogen technologies, the trilateral
group of co-sponsors proposes to develop the UN GTR in two phases:
(a)
Phase 1 (UN GTR for hydrogen-fuelled vehicles):
Establish a UN GTR by 2010 for hydrogen-fuelled vehicles based on a combination of
component-, subsystem-, and vehicle-level requirements. The UN GTR specifies that
each Contracting Party will use its existing national crash tests where vehicle crash
tests are required, but and will use the agreed upon maximum allowable level of
hydrogen leakage as the crash test leakage requirement. The new Japanese national
regulation, any available research and test data will be used as a basis for developing
this first phase of the UN GTR.
(b)
Phase 2 (Assess future technologies and harmonise crash tests):
Amend the UN GTR to maintain its relevance with new findings based on new research
and the state of the technology beyond Phase 1. Discuss how to harmonise crash test
requirements for HFCV regarding whole vehicle crash testing for fuel system integrity.
10. The UN GTR will consist of the following key elements:
(a)
Component and subsystem level requirements (non-crash test based):
Evaluate the non-crash requirements by reviewing analyses and evaluations
conducted to justify the requirements. Add and subtract requirements or amend test
procedures as necessary, based on existing evaluations or on quick evaluations that
could be conducted by Contracting Parties and participants. Avoid design specific
requirements to the extent possible and do not include provisions that are not
technically justified. The main areas of focus are:
(i)
(ii)
(iii)
Performance requirements for hydrogen storage systems, high-pressure
closures, pressure relief devices, and fuel lines;
Electrical isolation, safety and protection against electric shock (in use);
Performance and other requirements for subsystem integration in the vehicle.
(b)
Vehicle-level requirements:
Examine the risks posed by the different types of fuel systems in different crash modes.
Review and evaluate analyses and crash tests conducted to examine the risks and
identify appropriate mitigating measures for hydrogen-fuelled vehicles. The main areas
of focus are as follows:
(i)
(ii)
In-use and post-crash limits on hydrogen releases. Post-crash leakage limits
apply following execution of crash tests (front, side and rear) that are specified
in national requirements for crash safety testing in each jurisdiction;
In-use and post-crash requirements for electrical isolation and protection against
electric shock. Post-crash electrical safety criteria apply following execution of
crash tests (front, side and rear) that are specified in national requirements for
crash safety testing in each jurisdiction.

14. A high-level schematic depicting the functional interactions of the major systems in a
hydrogen-fuelled fuel cell vehicle (HFCV) is shown in Figure 1. During fuelling, hydrogen is
supplied to the vehicle through the fuelling receptacle and flows to the hydrogen storage
system. The hydrogen supplied to and stored within the hydrogen storage system can be
either compressed gaseous or liquefied hydrogen. When the vehicle is started, hydrogen gas
is released from the hydrogen storage system. Pressure regulators and other equipment
within the hydrogen delivery system reduce the pressure to the appropriate level for operation
of the fuel cell system. The hydrogen is electro-chemically combined with oxygen (from air)
within the fuel cell system to produce high-voltage electric power. That electric power is
supplied to the electric propulsion power management system where it is used to power
electric drive motors and/or charge batteries and ultra-capacitors.
Figure 1
Example of a High-level Schematic of the Key Systems in HFCVs
15. Figures 2 to 4 illustrate typical layouts of key components in the major systems of a typical
hydrogen fuel cell vehicle (HFCV). The fuelling receptacle is shown in a typical position on
the rear quarter panel of the passenger car, however, positioning may vary depending on the
vehicle type. As with gasoline containers, hydrogen storage containers, whether compressed
gas or liquefied hydrogen, are usually mounted transversely in the rear of passenger car, but
could also be mounted differently, such as lengthwise in the middle tunnel of the vehicle or
on the roof in case of buses. Fuel cells and ancillaries are usually located (as shown) under
the passenger compartment or in the traditional "engine compartment," along with the power
management, drive motor controller, and drive motors. Given the size and weight of traction
batteries and ultra-capacitors, these components are usually located in the vehicle to retain
the desired weight balance for proper handling of the vehicle.

2. Hydrogen Fuelling System
Figure 4
Example of a Hydrogen Fuel Cell Truck
17. Either liquefied or compressed gas may be supplied to the vehicle at a fuelling station,
depending on the type of hydrogen storage system in the vehicle. At present, hydrogen is
most commonly dispensed to vehicles as a compressed gas that is dispensed at pressures
up to 125% of the nominal working pressure (NWP) of the vehicle to compensate for transient
heating from adiabatic compression during fuelling.
18. Regardless of the state of the hydrogen, the vehicles are fuelled through a special fuelling
nozzle on the fuel dispenser at the fuelling station that connects with the fuelling receptacle
on the vehicle to provide a "closed system" transfer of hydrogen to the vehicle. The fuelling
receptacle on the vehicle contains a check valve (or other device) that prevents leakage of
hydrogen out of the vehicle when the fuelling nozzle is disconnected.
3. Hydrogen Storage System
19. The hydrogen storage system consists of all components that form the primary high pressure
boundary for containment of stored hydrogen. The key functions of the hydrogen storage
system are to receive hydrogen during fuelling, contain the hydrogen until needed, and then
release the hydrogen to the fuel cell system or the ICE for use in powering the vehicle. At
present, the most common method of storing and delivering hydrogen fuel on-board is in
compressed gas form. Hydrogen can also be stored as liquid (at cryogenic conditions). Each
of these types of hydrogen storage systems are described in the following sections.
20. Additional types of hydrogen storage, such as cryo-compressed storage, may
be covered in future revisions of this UN GTR once their development has matured.
Cryo-Compressed Hydrogen (CcH2) storage is a hybrid between liquid and compressed gas
storage which can be fuelled with both cryogenic-compressed and compressed hydrogen gas.
(a)
Compressed Hydrogen Storage System

24. A container may store hydrogen in a single chamber or in multiple permanently interconnected
chambers. Closure should not occur between the permanently interconnected chambers.
Disassembly of a container should not be permitted and should result in permanent removal
from service of the container.
25. A container might have container attachments that are non-pressure bearing parts which
provide additional support and/or protection to the container.
26. During fuelling, hydrogen enters the storage system through a check valve. The check valve
prevents back-flow of hydrogen into the fuelling line.
27. An automated hydrogen shut-off valve prevents the out-flow of stored hydrogen when the
vehicle is not operating or when a fault is detected that requires isolation of the hydrogen
storage system.
28. In the event of a fire, thermally activated pressure relief devices (TPRDs) provide a controlled
release of the gas from the compressed hydrogen storage containers before the high
temperatures in the fire weaken the containers and cause a hazardous rupture. TPRDs are
designed to vent the entire contents of the container rapidly. They do not reseat or allow repressurisation
of the container. Storage containers and TPRDs that have been subjected to
a fire are expected to be removed from service and destroyed.
(b)
Liquefied Hydrogen Storage System
29. Since on-road vehicle experience with liquefied hydrogen storage systems is limited and
constrained to demonstration fleets, safety requirements have not been comprehensively
evaluated nor have test procedures been widely examined for feasibility and relevance to
known failure conditions. Therefore optional requirements and test procedures for vehicles
with liquefied hydrogen storage systems are presented in Section G of this preamble and
Paragraph 7. of the text of the regulation, respectively, for consideration by Contracting
Parties for possible adoption into their individual regulations. It is expected that these
requirements will be considered as requirements in a future UN GTR that applies to vehicles
with liquefied hydrogen storage systems.
4. Hydrogen Fuel Delivery System
30. The hydrogen fuel delivery system transfers hydrogen from the storage system to the
propulsion system at the proper pressure and temperature for the fuel cell (or ICE) to operate.
This is accomplished via a series of flow control valves, pressure regulators, filters, piping,
and heat exchangers. In vehicles with liquefied hydrogen storage systems, both liquid and
gaseous hydrogen could be released from the storage system and then heated to the
appropriate temperature before delivery to the ICE or fuel cell system. Similarly, in vehicles
with compressed hydrogen storage systems, thermal conditioning of the gaseous hydrogen
may also be required, particularly in extremely cold, sub-freezing weather.
31. The fuel delivery system shall reduce the pressure from levels in the hydrogen storage system
to values required by the fuel cell or ICE system. In the case of a 70MPa NWP compressed
hydrogen storage system, for example, the pressure may have to be reduced from as high as
87.5MPa to less than 1MPa at the inlet of the fuel cell system, and typically under 1.5MPa at
the inlet of an ICE system. This may require multiple stages of pressure regulation to achieve
accurate and stable control and over-pressure protection of down-stream equipment in the
event that a pressure regulator fails. Over-pressure protection of the fuel delivery system may
be accomplished by venting excess hydrogen gas through pressure relief valves or by
isolating the hydrogen gas supply (by closing the shutoff valve in the hydrogen storage
system) when a down-stream over-pressure condition is detected.

7. Internal Combustion Engine (ICE)
39. Hydrogen fuel may also be used for internal combustion engines instead of fuel cell systems.
Although several adaptations will be required to use hydrogen in ICE, the principle of the
combustion is the same as that of gasoline engines and, therefore, most of the drivetrain of
gasoline engine vehicles can be utilised. The hydrogen fuelling system and hydrogen storage
system will be the same as that of HFCV while the fuel delivery system will be adapted for an
injection system of an ICE vehicle.
D. RATIONALE FOR SCOPE, DEFINITIONS AND APPLICABILITY
1. Rationale for Paragraph 2 (Scope)
40. This UN GTR applies to hydrogen storage systems having nominal working pressures (NWP)
of 70MPa or less, with an associated maximum fuelling pressure of 125% of the nominal
working pressure. Systems with NWP up to 70MPa include storage systems currently
expected to be of commercial interest for vehicle applications. In the future, if there is interest
in qualifying systems to higher nominal working pressures, the test procedures for
qualification will be re-examined.
41. This UN GTR applies to fuel storage systems securely attached within a vehicle for usage
throughout the service life of the vehicle. It does not apply to storage systems intended to be
exchanged in vehicle fuelling. This UN GTR does not apply to vehicles with storage systems
using chemical bonding of hydrogen; it applies to vehicles with storage by physical
containment of gaseous or liquid hydrogen.
42. The hydrogen fuelling infrastructure established prior to 2010 applies to fuelling of vehicles
up to 70MPa NWP. This UN GTR does not address the requirements for the fuelling station
or the fuelling station/vehicle interface.
43. This UN GTR provides requirements for fuel system integrity in vehicle crash conditions, but
does not specify vehicle crash conditions. Contracting Parties to the
1998 Agreement are expected to execute crash conditions as specified in their national
regulations. For the case of heavy-duty vehicles where crash tests are not available, various
Contracting Parties believe that a minimal level of safety by means of testing the fuel system
integrity would need to be introduced. In this regard, acceleration tests of gas storage
containers and their fixtures have been well established in several regulations, such as UN
Regulation No. 67 on liquefied petroleum gases (LPG), UN Regulation No. 110 on
compressed natural gas (CNG) and liquefied natural gas (LNG), as well as European Union
Regulation (EC) No. 406/2010, implementing Regulation (EC) No. 79/2009 on hydrogen
safety. In these acceleration tests, the storage system and its fixture to the vehicle structures
are subjected to accelerations according to the vehicle category. A calculation method can be
used instead of physical testing if its equivalence can be demonstrated.
44. Consensus was not achieved on the acceleration test during Phase 2 of the Informal Working
Group of UN GTR No. 13 when Contracting Parties did not agree on the goal of the
acceleration test or how it addressed a particular safety need. It was agreed, however, to
further investigate fuel system integrity in a subsequent Phase 3, which would allow for the
collection of field data from original equipment manufacturers (OEMs) and other relevant
parties. Phase 3 would also consider other fuel system integrity requirements such as a side
impact test.

E. RATIONALE FOR PARAGRAPH 5. (PERFORMANCE REQUIREMENTS)
1. Compressed Hydrogen Storage System Test Requirements and Safety Needs
50. The containment of the hydrogen within the compressed hydrogen storage system is essential
to successfully isolate the hydrogen from the surroundings and
down-stream systems. The storage system is defined to include all closure surfaces that
provide primary containment of high-pressure hydrogen storage. The definition provides for
future advances in design, materials and constructions that are expected to provide
improvements in weight, volume, conformability and other attributes.
51. Requirements for Compressed Hydrogen Storage System (CHSS) and its primary closures
are defined in Paragraph 5.1. The provision in Paragraph 5.1.(b) allows Contracting Parties
to require that primary closure devices be mounted directly on the container. If needed,
manufacturers can choose to locate additional TPRDs in alternative locations on the
container. However, any additional TPRDs should be connected directly to the containers by
using supply lines that have demonstrated mechanical integrity and durability as part of
qualification tests for CHSS (Paragraphs 5.1.1. and 5.1.2.).
52. Performance test requirements for all compressed hydrogen storage systems in on road
vehicle service are specified in Paragraph 5.1. The performance-based requirements address
documented on-road stress factors and usages to assure robust qualification for vehicle
service. The qualification tests were developed to demonstrate capability to perform critical
functions throughout service including fuelling/defueling, parking under extreme conditions,
and performance in fires without compromising the safe containment of the hydrogen within
the storage system. These criteria apply to qualification of storage systems for use in new
vehicle production.
53. Conformity of Production with Storage Systems Subjected to Formal Design Qualification
Testing:
Manufacturers shall ensure that all production units comply with the requirements of
performance verification testing in Paragraph 5.1.2. In addition, manufacturers are expected
to monitor the reliability, durability and residual strength of representative production units
throughout service life.
54. Organisation of Requirements:
Paragraph 5.1. design qualification requirements for compressed hydrogen storage system
include:
5.1.1. Verification tests for baseline metrics;
5.1.2. Verification test for performance durability (hydraulic sequential tests);
5.1.3. Verification test for expected on-road performance (pneumatic sequential tests);
5.1.4. Verification test for service-terminating performance in fire.

(b)
Second example:
An overriding requirement for initial burst pressure (>225% NWP for carbon fibre
composite containers and >350% NWP for glass fibre composite containers) has been
used previously in some places for lower pressure CNG containers. The basis for this
type of burst pressure requirement for new (unused) containers was examined. A
credible quantitative, data-driven basis for historical requirements linked to demands of
on-road service was not identified. Instead, modern engineering methods of identifying
stressful conditions of service from decades of experience with real-world usage and
designing qualification tests to replicate and compound extremes of those conditions
were used to force systems to demonstrate capability to function and survive a lifetime's
exposure. However, a risk factor that could be identified as not already addressed by
other test requirements and for which a burst pressure test would be relevant was the
demonstration of capability to resist burst from over-pressurisation by a fuelling station
through-out service life. The more stringent test condition applies to containers at the
"end-of-life" (as simulated by extreme test conditions) rather than new (unused)
containers. Therefore, a residual (end-of-life) requirement of exposure (without burst)
to 180% NWP for 4min was adopted based on the demonstrated equivalence of the
probability for failure after 4min at 180% NWP to failure after 10h at 150% NWP (based
on time to failure data for "worst-case" glass composite strands). Maximum fuelling
station over-pressurisation is taken as 150% NWP. Experiments on highly insulated
containers have shown cool down from compressive heating lasting on the order of
10h. An additional requirement corresponding to minimum burst pressure of 200%
NWP for new, unused containers has been under consideration as a screen for
minimum new containers capability with potential to complete the durability test
sequence requiring burst pressure above 180% NWP considering <±10% variability in
new containers strength. The historical minimum, 225% NWP has been adopted in this
document as a conservative placeholder without a quantitative data-driven basis but
instead using previous history in some Contracting Parties with the expectation that
additional consideration and data/analyses will be available to support the 225% NWP
value or for reconsideration of the minimum new containers burst requirement.
58. The historical minimum of 225% NWP for carbon-fibre composite containers, had been
adopted as a placeholder because of the lack of quantitative data in UN GTR No. 13, Phase 1.
In subsequent discussions of Phase 2, the capability of containers to achieve the end-of-life
burst pressure of 180% NWP was verified based on the data of carbon-fibre composite
containers for 70MPa provided by Japan, assuming that the variation of the initial burst
pressure is within BP ±10%. As a result, it has been validated that the initial burst pressure
should be specified as 200% NWP for carbon-fibre composite containers.

62. The baseline initial burst pressure requirements differ from the "end-of-life" burst pressure
requirements that conclude the test sequences in Paragraphs 5.1.2. and 5.1.3. The baseline
burst pressure pertains to a new, unused container and the
"end-of-life" burst pressure pertains to a container that has completed a series of performance
tests (Paragraphs 5.1.2. or 5.1.3.) that replicate conditions of worst-case usage and
environmental exposure in a full service life. Since fatigue accumulates over usage and
exposure conditions, it is expected that the "end-of-life" burst pressure (i.e. burst strength)
could be lower than that of a new and unexposed container.
(i)
Rationale for Paragraph 5.1.1.1. Baseline Initial Burst Pressure
63. Paragraph 5.1.1.1. establishes the midpoint initial burst pressure (BP ) and verifies that initial
burst pressures of systems in the qualification batch are within the range BP ±10%. BP is
used as a reference point in performance verification (Paragraphs 5.1.2.8. and 5.1.3.5.) and
verification of consistency within the qualification batch. Paragraph 5.1.1.1. verifies that BP
is greater than or equal to 225% NWP or 350% NWP (for glass fibre composites), values
tentatively selected without data-driven derivation but instead based on historical usage and
applied here as placeholders with the expectation that data or analysis will be available for
reconsideration of the topic in Phase 2 of the development of this UN GTR. For example, a
200% minimum initial burst pressure requirement can be supported by the data-driven
performance-linked justification that a greater-than 180% NWP end-of-service burst
requirement (linked to capability to survive the maximum fuelling station over-pressurisation)
combined with a 20% lifetime decline (maximum allowed) from median initial burst strength is
equivalent to a requirement for a median initial burst strength of 225% NWP, which
corresponds to a minimum burst strength of 200% NWP for the maximum allowed 10%
variability in initial strength. The interval between Phase I and Phase II provides opportunity
for development of new data or analysis pertaining to a 225% NWP (or another per cent NWP)
minimum prior to resolution of the topic in Phase 2.
64. In Paragraph 5.1.1.1., the minimum initial burst pressure was specified as 225% NWP for
carbon fibre containers (and 350% NWP for glass fibre containers) as a historical placeholder
in UN GTR No. 13, Phase 1.

67. Verification method via the sequential hydraulic tests: The variation in initial burst pressure
and end-of-life burst pressure, as well as the average of degradation ratio between the initial
and the end-of-life burst pressure were investigated using test data from carbon-fibre
containers (N ≥ 10). The containers were selected from a single batch with known capability
of greater than 225% NWP initial burst pressure.
Figure 7
Results from the Verification Test
Figure 8
BP and BP Distribution

74. Regardless of the container failure mode, this requirement provides sufficient protection for
safe container use over the life of the vehicle. The minimum distance travelled prior to a
container leaking would depend on a number of factors including the number of cycles chosen
by the Contracting Party and the fill mileage for the vehicle. Regardless, the minimum design
of 7,500 cycles before leak and using only 320km (200mi) per fill provides over 1.6 million km
(1 million miles) before the container would fail by leakage. Worst case scenario would be
failure by rupture in which case the container shall be capable of withstanding 22,000 cycles.
For vehicles with nominal on-road driving range of 480km (300mi) per full fuelling, 22,000 full
fill cycles corresponds to over 10 million km (6 million miles), which is beyond a realistic
extreme of on-road vehicle lifetime range (see discussion in Paragraph 5.1.1.2.2. below).
Hence, either the container demonstrates the capability to avoid failure (leak or rupture) from
exposure to the pressure cycling in on-road service, or leakage occurs before rupture and
thereby prevents continued service that could potentially lead to rupture.
75. A greater number of pressure cycles, 22,000, is required for demonstration of resistance to
rupture (in the absence of intervening leak) compared to the number of cycles required for
demonstration of resistance to leak (between 7,500 and 11,000) because the higher severity
of a rupture event suggests that the probability of that event per pressure cycle should be
lower than the probability of the less severe leak event. Risk = (probability of event) × (severity
of event).
(Note:
Cycling to a higher pressure than 125% NWP could elicit failure in less testing time,
however, that could elicit failure modes that could not occur in real world service.)
b. Rationale for Number of Cycles, Number of hydraulic pressure cycles in Qualification Testing:
Number of Cycles Greater than or Equal to 7,500 and Less than or Equal to 11,000
76. The number of hydraulic test pressure cycles is to be specified by individual Contracting
Parties primarily because of differences in the expected worst-case lifetime vehicle range
(distance driven during vehicle service life) and worst-case fuelling frequency in different
jurisdictions. The differences in the anticipated maximum number of fuellings are primarily
associated with high usage commercial taxi applications, which can be subjected to very
different operating constraints in different regulatory jurisdictions. For example:
(a)
(b)
Vehicle fleet odometer data (including taxis): Sierra Research Report No. SR2004-09-04
for the California Air Resource Board (2004) reported on vehicle lifetime distance
travelled by scrapped California vehicles, which all showed lifetime distances travelled
below 560,000km (350,000mi). Based on these figures and 320 – 480km (200 – 300mi)
driven per full fuelling, the maximum number of lifetime empty-to-full fuellings can be
estimated as 1,200 – 1,800;
Vehicle fleet odometer data (including taxis): Transport Canada reported that required
emissions testing in British Columbia, Canada, in 2009 showed the 5 most extreme
usage vehicles had odometer readings in the 800,000 – 1,000,000km (500,000 –
600,000mi) range. Using the reported model year for each of these vehicles, this
corresponds to less than 300 full fuellings per year, or less than 1 full fuelling per day.
Based on these figures and 320 – 480km (200 – 300mi) driven per full fuelling, the
maximum number of empty-to-full fuellings can be estimated as 1,650 – 3,100;

Table 1
Results of the Japanese Study
Vehicle Type
HD
Commercial
LD
Commercial
Max svc.
Life
Max lifetime
miles travelled
Lifetime No. of
fills
("pressure test
cycles")
15 yrs – – 11,000
20 yrs 3,500,000km 8,450 11,000
25 yrs 4,000,000km 9,750 11,000
Ref: UN GTR13
Phase 2
Proposal
15 yrs – – 5,500, 7,500 or 11,000
20 yrs 2,100,000km 6,560 11,000
25 yrs 2,400,000km 7,440 11,000
While the details of this analysis can be found in the document "UN GTR13-11-12b TF1
210927 Estimation of VMT TF1-JAMA.pdf (https://wiki.unece.org/ download/
attachments/140706658/UN GTR 13-11-12b%20TF1%20% 20210927%20 Estimation
%20of%20VMT%20TF1-JAMA. pdf? api=v2), a brief summary of the methodology is as
follows;
(i)
(ii)
Records from periodic legal inspections were collected from about 400,000 onroad
vehicles. Heavy-duty vehicles were defined according to the Japanese
categorization as those with greater than a number of 10 seats and a loading
capacity of greater than 1,250kg (assuming the vehicle weight is greater than
3,500kg);
The annual VMT (km/year) of each vehicle was calculated by the taking the
difference between the records of the current inspection less the previous
inspection. An average vehicle mile travelled (VMT) per year (VMT ) was
calculated for the vehicles of a certain age. A maximum VMT for each year for
each vehicle age was also calculated by adding three times the standard
deviation of the VMT to the average.
maxVMT = aveVMT + 3sigma*VMT

Vehicle Type
HD
Commercial
Max svc.
Life
Table 2
Results of the German Study
Max lifetime
miles travelled
Lifetime No.
of fills
("pressure test
cycles")
Ref: UN GTR No. 13
Phase 2 Proposal
20 yrs 2,300,340km 6,390 11,000
Semi-trailer truck 25 yrs 2,875,425km 7,987 11,000
(c)
United States – The National Renewable Energy Laboratory (NREL) published a study
in 2021 which examined the end-of-life conditions of compressed natural gas vehicle
fuel tanks. The focus was to investigate the structural integrity of CNG fuel tanks under
nominal operating conditions at the end of their service life to help manufacturers to
"better identify, understand, and mitigate safety risks and address barriers and
opportunities related to CNG storage onboard vehicles." A total of 60 Type II and
Type IV CNG fuel tanks from transit buses used for 15 years were obtained from the
Los Angeles County Metropolitan Transportation Authority.
These tank designs had been qualified under CSA/ANSI NGV 2 but the exact service
history of each tank could not be obtained. Still, each tank was estimated to have been
cycled from 1,000 to 4,400 pounds per square inch gauge (psig), six times per week
for 15 years, resulting in an estimated total of 4,680 fatigue cycles over its useful life.
Non-destructive evaluation (via modal acoustic emission, MAE) and physical testing
(per CSA/ANSI NGV 2) were performed on these tanks. Twenty of the 60 tanks were
burst-tested without being subjected to any additional damage to establish a baseline
understanding of the tank’s structural integrity at EOL.
An additional 20 tanks were subjected to artificial notch and impact damage followed
by fatigue cycling and burst pressure testing to understand structural durability. Another
20 tanks were subjected to hydraulic fatigue cycling followed by a burst test to simulate
continued use of the tanks beyond their defined EOL.
The results of the structural integrity testing of the Type III and Type IV CNG fuel tanks
at the end of their defined useful life of 15 years suggests the "potential opportunity of
continued use of tanks", as all 60 tanks were beyond their defined useful life of 15 years
but seemed to be structurally sound based on the results of the initial visual inspection
and MAE examination. The tanks maintained the required strength for burst
pressurization at the time of manufacture and did not experience any significant
strength degradation during their use in service as determined by the burst
pressurization test.
Even after additional hydraulic fatigue cycling, the tank integrity based on the burst test
"suggest the potential of additional service life for CNG tanks beyond their defined end
of life."

(d) Severe usage: exposure to chemicals in the on-road environment
(Paragraph 5.1.2.4.)
(i)
(ii)
(iii)
(iv)
(v)
(vi)
Fluids include fluids used on vehicles (battery acid and washer fluid), chemicals
used on or near roadways (fertiliser nitrates and lye), and fluids used in fuelling
stations (methanol and gasoline);
The primary historical cause of rupture of high pressure vehicle containers (CNG
containers), other than fire and physical damage, has been stress corrosion
rupture – rupture occurring after a combination of exposure to corrosive
chemicals and pressurisation;
Stress corrosion rupture of on-road glass-composite wrapped containers
exposed to battery acid was replicated by the proposed test protocol; other
chemicals were added to the test protocol once the generic risk of chemical
exposure was recognised;
Penetration of coatings from impacts and expected on-road wear can degrade
the function of protective coatings – recognised as a contributing risk factor for
stress corrosion cracking (rupture); capability to manage that risk is therefore
required;
The ambient temperature limits have been changed to 20 ± 15°C unless
otherwise specified. The 20 ± 5°C requirement is an unnecessarily stringent test
temperature range for the container skin and fluid. The new limits allow skin and
fluid temperatures to rise to a reasonable temperature that is incapable of
harming a robust container or materially affecting test performance. Additionally,
these limits are consistent with those specified in ISO 554:1976 ("Standard
Atmospheres For Conditioning And/Or Testing – Specifications").
Chemical exposure can be continued up to the last 10 cycles and can be
removed after the cycling is complete. Containers have been shown to be
unaffected after a few additional hours of chemical exposure. This change makes
the test less burdensome without changing its severity.
(e)
Extreme number of fuellings/defuelings
Rationale for number of cycles greater than 7,500 and less than 11,000 is provided in
Paragraphs 76-79 Section E.1.(a).(ii).b above.

(h)
Extended and severe usage:
High temperature full-fill parking up to 25 years (prolonged exposure to high pressure)
(Paragraph 5.1.2.5) To avoid a performance test lasting for 25 years, a timeaccelerated
performance test using increased pressure developed using experimental
material data on currently used metals and composites, and selecting the worst-case
for stress rupture susceptibility, which is glass fibre reinforced composite. Use of
laboratory data to establish the equivalence of testing for stress rupture at 100% NWP
for 25 years and testing at 125% NWP for 1,000h (equal probability of failure from
stress rupture) is described in SAE Technical Paper 2009-01-0012 (Sloane, "Rationale
for Performance-based Validation Testing of Compressed Hydrogen Storage", 2009).
Laboratory data on high pressure container composite strands – documentation of
time-to-rupture as a function of static stress without exposure to corrosives – is
summarised in Aerospace Corp Report No. ATR-92(2743)-1 (1991) and references
therein.
(i)
(ii)
(iii)
No formal data is available on parking duration per vehicle at different fill
conditions. Examples of expected lengthy full fill occurrences include vehicles
maintained by owners at near full fill conditions, abandoned vehicles and
collectors' vehicles. Therefore, 25 years at full fill is taken as the test requirement;
The testing is performed at +85°C because some composites exhibit a
temperature-dependent fatigue rate (potentially associated with resin oxidation)
(J. Composite Materials 11, 79 (1977)). A temperature of +85°C is selected as
the maximum potential exposure because under-hood maximum temperatures
of +82°C have been measured within a dark-coloured vehicle parked outside on
asphalt in direct sunlight in 50°C ambient conditions. Also, a compressed gas
container, painted black, with no cover, in the box of a black pickup truck in direct
sunlight in 49°C had maximum/average measured container skin surface
temperatures of 87°C (189°F)/70°C (159°F);
On-road experience with CNG containers – there have not been reports of any
on-road stress rupture without exposure to corrosives (stress corrosion cracking)
or design anomaly (hoop wrap tensioned for liner compression without
autofrettage). Paragraph 5.1.2. testing that includes chemical exposure test and
1,000h of static full pressure exposure simulates these failure conditions.
(i) Residual proof pressure (Paragraph 5.1.2.7.)
(i)
(ii)
(iii)
Fuelling station over-pressurisation constrained by fuelling station requirements
to less than or equal to 150% NWP. (This requirement for fuelling stations shall
be established within local codes/regulations for fuelling stations);
Laboratory data on static stress rupture used to define equivalent probability of
stress rupture of composite strands after 4min at 180% NWP as after 10h at
150% NWP as the worst case (SAE Technical Report 2009-01-0012). Fuelling
stations are expected to provide over-pressure protection up to 150% NWP;
Testing at "end-of-life" provides assurance to sustain fuelling station failure
throughout service.

85. Data used in developing Paragraph 5.1.3. test protocol include:
(a)
Proof pressure test (Paragraph 5.1.3.1.) – routine production of pressure containers
includes a verifying, or proof, pressure test at the point of production, which is 150%
NWP as industry practice, i.e. 20% above the maximum service pressure;
(b) Leak-free fuelling performance (Paragraph 5.1.3.2.)
(i)
Expected environmental conditions – weather records show temperatures less
than or equal to -40°C occur in countries north of the 45th parallel; temperatures
~50°C occur in desert areas of lower latitude countries; each with frequency of
sustained extreme temperature ~5% in areas with verifiable government records.
Actual data shows ~5% of days have a minimum temperature below -30°C.
Therefore sustained exposure to below -30°C is less than 5% of vehicle life since
a daily minimum is not reached for a full 24h period. Data record examples
(Environment Canada 1971-2000):
https://climate.weather.gc.ca/climate_normals/index_e.html#1971
(ii)
Number of fuelling/defueling cycles
a. The number of full fuellings required to demonstrate capability for leakfree
performance in expected service is taken to be 500.
i. Expected vehicle lifetime range is taken to be 250,000km
(155,000mi);
Figure 9
Vehicle Age vs. Average Odometer

v. Test experience:
Mechanical failures of vehicle storage systems associated with gas
intrusion into wrap/liner and interlaminate interfaces develop in ~50
full fuellings;
vi.
Test experience:
70MPa hydrogen storage systems that passed the test
requirements of CSA/ANSI NGV 2 have failed during the test
conditions of Paragraph 5.1.3. in failure modes that would be
expected to occur in on-road service. The Powertech report
(McDougal, M., "SAE J2579 Validation Testing Program Powertech
Final Report", National Renewable Energy Laboratory Report No.
SR-5600-49867 (www.nrel.gov/ docs/fy11osti/49867.pdf) cites two
failures of systems with containers that have qualified for service:
metal-lined composite container valve leak and in-container
solenoid leak, polymer-lined composite container leak due to liner
failure. The polymer-lined composite container failure by leakage
was on a container that was qualified to CSA/ANSI NGV 2 modified
for hydrogen. The metal-lined composite failure of the container
valve was on a valve qualified to EIHP rev12b. Report conclusion:
"The test sequences in SAE TIR J2579 have shown that containers
with no known failures in service either met the requirements of the
tests, or fail for reasons that are understood and are representative
of future service conditions."
(iii)
Fuelling conditions
a. The filling profile was originally set to 3min as it represented the fastest
empty-to-full fuelling for 70MPa fast fuelling with -40°C fuel temperature;
however, test experience with a single 3min pressurisation is an oversimplification
of the required fuelling process that often results of over-fills
of containers above 100%. For this reason, Table 7b was developed
based on SAE J2601 (Fuelling Protocols for Light Duty Gaseous
Hydrogen Surface Vehicles) and inserted in Paragraph 6.2.4.1. to provide
more appropriate pressurisation ramp rates as a function of CHSS volume
for the various ambient and fuel delivery temperature conditions that are
being evaluated in the test protocol.
Since SAE J2601 focuses on the fuelling of light-duty vehicles, the tables
were conservatively extrapolated to larger CHSS container volumes using
the formula in SAE J2601. Additionally, in the case of 50L and 100L CHSS
volumes at 20°C and 50°C ambient temperatures, the pressurisation ramp
rates were adjusted to account for differences between fuel delivery
equipment in real-world dispensing stations where large thermal masses
(i.e. mass times specific heat) of break-aways, dispenser hoses, nozzles,
and receptacles can adversely affect the fuel delivery temperature to the
CHSS and test laboratories that do not need or utilize break-aways,
dispenser hoses, nozzles and receptacles.

(c) Leak-free parking at full fill (Paragraph 5.1.3.3.)
(i)
(ii)
(iii)
Leak and permeation are risk factors for fire hazards for parking in confined
spaces such as garages;
The leak/permeation limit is characterised by the many possible combinations of
vehicle and garages, and the associated test conditions. The leak/permeation
limit is defined to restrict the hydrogen concentration from reaching 25% Lower
Flammability Limit (LFL) by volume. The conservative 25% LFL limit is
conventionally adopted as the maximum concentration to accommodate
concentration inhomogeneities and is equivalent to 1% hydrogen concentration
in air. Data for hydrogen dispersion behaviour, garage and vehicle scenarios,
including garage sizes, air exchange rates and temperatures, and the calculation
methodology are found in the following reference prepared as part of the
European Network of Excellence (NoE) HySafe: P. Adams, A. Bengaouer, B.
Cariteau, V. Molkov, A.G. Venetsanos, "Allowable hydrogen permeation rate
from road vehicles", Int. Journal of Hydrogen Energy, volume 36, issue 3, 2011
pp 2742-2749;
The ventilation in structures where hydrogen vehicles can be parked is expected
to be at or below 0.18 air changes per hour under worst case conditions, but the
exact design value is highly dependent on the type and location of structures in
which the vehicles are parked. In the case of light-duty passenger vehicles, an
extremely low air exchange rate (of 0.03 volumetric air changes per hour) has
been measured in "tight" wood frame structures (with plastic vapor barriers,
weather-stripping on the doors, and no vents) that are sheltered from wind and
are very hot (55°C) with little daily temperature swings that can cause densitydriven
infiltration. The resulting discharge limit for a light-duty vehicle is
150mL/min (at 115% NWP for full fill at 55°C) when the vehicle fits into a garage
of 30.4m . Since the discharge limit has been found to be reasonably scalable
depending on the vehicle size, the scaling factor,
R = (V + 1) * (V + 0.5) * (V + 1)/ 30.4
where V , V , and V are the dimensions of the vehicle in meters, allows
calculation of the discharge limit for alternative garage/vehicle combinations to
those used to determine the 150mL/min discharge limit cited above.

Figure 10
Required Ventilation of Space Surrounding the Vehicle
(vi)
(vii)
The maximum pressure of a fully filled container at 55°C is 115% NWP
(equivalent state of charge to 125% NWP at 85°C and 100% NWP at 15°C);
A localised leak test is to be conducted to ensure that external leakage cannot
sustain a flame that could weaken materials and subsequently cause loss of
containment. Per Technical Report 2008-01-0726 ("Flame Quenching Limits of
Hydrogen Leaks"), the lowest flow of H that can support a flame is 0.028mg/s
from a typical compression fitting and the lowest leak possible from a miniature
burner configuration is 0.005mg/s. Since the miniature burner configuration is
considered a conservative "worst case", the maximum leakage criterion is
selected as 0.005mg/s;
(viii) Parking provides opportunity for hydrogen saturation of interlaminate layers,
wrap/liner interface, liner materials, junctures, O-rings, and joinings – fuelling
stresses are applied with and without exposure to hydrogen saturation.
Hydrogen saturation is marked by permeation reaching steady-state rate;
(ix)
By requiring qualification under the worst credible case conditions of raised
temperature, pressure cycling and equilibration with hydrogen, the permeation
verification removes uncertainty about permeation/ temperature dependence, and
long term deterioration with time and usage.

(d)
Rationale for Paragraphs 5.1.4. and 6.2.5. Verification Test for Service-Terminating
Performance in Fire
86. Verification of performance under service-terminating conditions is designed to prevent
rupture under severe conditions. Fire is the only service-terminating condition accounted for
in design qualification.
87. A comprehensive examination of CNG container in-service failures during the past decade
(SAE Technical Paper 2011-01-0251 (Scheffler, McClory et al., "Establishing Localised Fire
Test Methods and Progressing Safety Standards for FCVs and Hydrogen Vehicles")) showed
that, while some of fire incidents occurred on storage systems that did not utilise properly
designed thermally-activated pressure relief devices (TPRDs), the majority resulted when
TPRDs did not respond to protect the container because TPRDs were improperly installed
and did not sense the heat exposure even though the localised fire was able to degrade the
container wall and eventually cause the storage container to burst. The localised fire exposure
has not been addressed in previous regulations or industry standards. The fire test method in
Paragraph 6.2.5. addresses both localised and engulfing fires.
88. The fire test conditions of Paragraph 6.2.5. were based on vehicle-level tests by the Japanese
Automobile Research Institute (JARI) and US manufacturers. A summary of data is found in
paper SAE Technical Paper 2011-01-0251. As part of the preparatory requirements for this
regulation, the paper and data were reviewed for the purpose of improving reproducibility of
fire results. Key findings are as follows:
(a)
(b)
(c)
About 30-50% of the vehicle laboratory fires investigated resulted in conditions that
could be categorised as a localised fire since the data indicates that a composite
compressed gas container could have been locally degraded before conventional
TPRDs on end bosses (away from the local fire exposure) would have activated. A
temperature of 300°C was selected as the start of the localised fire condition as thermal
gravimetric analysis (TGA) indicates that composite container materials begin to
degrade rapidly at this temperature;
While vehicle laboratory fires often lasted 30-60min, the period of localised fire
degradation on the storage containers lasted less than 10min;
As shown in Figure 11, peak temperatures on the surface of cylinders used for the
vehicle fire test reached 700°C during the localized fire stage. While this temperature
is not as high as temperature levels experienced later during engulfing fire stage of the
vehicle fire, they are adequate to cause serious material degradation while also
challenging the ability of TPRDs to activate and vent the contents of the container;

89. Based upon the above findings, performance-based limits as shown in Figures 11 and 12; the
limits were defined to characterize the thermal exposure during the localized and engulfing
fire stages. The maximum cylinder surface temperature during the localized fire stage for the
side of the cylinder facing the fire was set to 50°C above the highest value that was
experienced during the JARI vehicle fire tests to provide a margin for testing. A maximum limit
for the engulfing stage was not necessary as the temperature is a naturally limited flame
temperature. The minimum surface temperatures on the side facing the flame were set to the
lowest value in the range of data during the engulfing fire stage but was limited to one standard
below average during the localized fire stage so that a challenging (but reasonable) thermal
condition even though the full range of data was significantly skewed.
90. Experience conducting container fire tests has found that the temperature on the side of the
cylinder opposing the intended fire exposure also needs to be controlled to minimize site-tosite
test variations as differences in the length of flames during the fire test can inadvertently
lead to temperatures above the JARI vehicle fire test experience on the side opposite the
intended fire exposure and subsequently cause excessive material degradation on the top of
the container and, in some cases, premature response of TPRD(s). For this reason, both the
minimum and maximum allowable temperatures for the engulfing fire stage were based on
the range of data that occurred during the vehicle fire tests, and the minimum and maximum
temperatures during the localized stage were limited to slightly less than one standard
deviation from average to maintain a challenging (but reasonable) thermal condition.
91. The temperature limits found on Figures 11 and 12 were also used to establish the maximum
and minimum allowable temperatures in Table 10 in Part II for the development and checkout
of burner used for fire testing. Since (as shown in Figure 13) the container is mounted above
the burner for fire testing, the bottom of the container faces the fire and the top of the container
is the side opposite the fire exposure, Table 10 in Part II defines criteria relative to the bottom
and top of the container as this terminology is consistent with container fire testing. Also, the
maximum temperature for the bottom of the cylinder was applied to thermocouple locations
on both the bottom centre and mid-height sides of the container as all these locations
represent the thermal exposure on the side facing the fire during the JARI vehicle fire tests.
Figure 13
Containers in a Fire Testing

Figure 15
Prescribed Arrangement of Air Pre-Mix Burner Nozzles
Figure 16
Burner Fuel Nozzles
Table 3
Definition of Burner Nozzles for the Prescribed Burner
Nozzle Description
Nozzle Manufacturer
Brand Name
Part Number
Nozzle Connection
Item
Description
Stainless Propane Gas Tip for Jet Burner
Thermova – Ningbo, China
OEM
ZZ15002
Screw-on 5/16-24 UNF Thread

99. A pre-test cylinder (fabricated from a steel pipe with caps) is used for the pre-test to confirm
proper operation of the burner zones. The pre-test cylinder that is similar to cylinders used in
JARI vehicle fire tests was required to ensure technical soundness of the empirical process
of thermal mapping the localized and engulfing burner zones and then comparing the results
to criteria based on the JARI vehicle fire tests. The pre-test cylinder is instrumented in the
same manner as the containers in the vehicle fire tests and mounted above the burner in the
same manner as the CHSS to be fire tested (see Figure 18). After initial development testing
by JARI, a round robin test was conducted. The thermal mapping was performed by stepping
up the fuel flow rate over the expected operating range of HRR/A for the burner. Results were
then compared to the criteria in Table 10 in Part II and used to define the allowable operating
ranges and to select the fuel settings for the localized and engulfing zones of the burner.
Figure 18
Pre-test Cylinder Mounted Above the Burner for Thermal Mapping
100. Results of the thermal mapping of the localized burner are shown in Figures 19 to 22 based
on available data from the round robin testing. Values are based on 60-second rolling
averages of readings from the round robin testing described above. The location of the various
temperature readings is given in Paragraph 6.2.5.4.3. The figures show that the test
laboratories have found acceptable operation between 200 and 500kW/m . The suggested
setting for the localized fire test of 300kW/m was established to provide a challenging
condition that was acceptable for most laboratories. Typical values in Table 4 for the localized
fire stage are based on 60-second rolling averages of the data at 300kW/m and are used for
burner checkout to verify operation is as expected.

Figure 20a
Pre-test Cylinder Temperatures on Sides During
Thermal Mapping of Localized Burner (Front side)
Figure 20b
Pre-test Cylinder Temperatures on Sides During
Thermal Mapping of Localized Burner (Rear side)

101. The results of the thermal mapping of the engulfing burner are shown in Figures 23 to 26. As
with the localized burner thermal mapping, values are based on 60-second rolling averages
of readings by test laboratories participating in the round robin testing, and the location of the
various temperature readings are given in Paragraph 6.2.5.4.3. The figures show that the test
laboratories have found acceptable operation between 400 and 1,000kW/m . The suggested
setting for the localized fire test of 700kW/m was established to provide a challenging
condition that was acceptable for most laboratories.
Table 5
Typical Values for Pre-test Cylinder and Burner Monitor
Temperatures for Engulfing Burners (at 700kW/m )
Parameter
TB 600 – 950°C
Average of TMF and TMR 600 – 950°C
TU 400 – 850°C
TB 800 – 1,050°C
Typical Temperatures Based on
60-second Rolling Averages
Figure 23
Pre-test Cylinder Temperatures on Bottom (Centre)
During Thermal Mapping of Engulfing Burner

Figure 26
Temperatures of Burner Monitor During
Thermal Mapping of Engulfing Burner
102. Thermal imaging of the container during the fire tests was also performed to ensure that the
prescribed burner delivers uniform thermal conditions over the targeted area of fire exposure.
See Figure 27.
Figure 27
Example of the Thermal Imaging Results for the Prescribed Burner Configuration
103. Depending on whether the test is conducted indoors or outdoors, and on the local weather
conditions if conducted outdoors, wind shielding may be required for the intended thermal
conditions for the fire tests. To ensure that wind shields do not interfere with the drafting of
the fire during the fire tests and cause variations in results, wind shields as defined in
Paragraph 6.2.5.2. need to be installed for the pre-test checkout of the burner and test setup,
as well as for the actual CHSS fire test.

109. The length of the engulfing fire is extended by a maximum of 1.4m from 250mm for the
localized fire stage to a maximum of 1.65m for the engulfing fire stage. The limit of 1.65m for
the engulfing fire is based on existing regulations and experience in the Canada and the
United States of America, and both this length and time for progression for the localized and
engulfing fire stages are supported by the JARI vehicle fire test data.
110. Examples of commonly encountered situations are provided below based on the above
requirements for targeting the localized fire zone on the CHSS and positioning the engulfing
fire zone under the CHSS:
(a)
Figures 28 to 30 address containers that are protected by a single TPRD.
Figure 28 deals with, for example, a cylindrical container. The localized burner is
located under the end of the container that is opposite the TPRD to maximize the
distance from the TPRD (without extending beyond the spherical head of the
container). The engulfing burner extends to the left (toward the TPRD) to the maximum
allowable of 1,400 ± 50mm. In Case 1, the distance to the TPRD from the localized
burner is less than the maximum allowable extension of the engulfing burner so the
engulfing burner is allowed to extend beyond the container. Conversely, in Case 3, the
distance to the TPRD from the localized burner is greater than the maximum allowable
extension so the engulfing burner zone does not reach under the TPRD.
The examples in Figure 28 depict a container assembly where the TPRD is placed
along the axis of the cylinder so the extension of the engulfing burner is also located
along the axis as illustrated in Case 1 of Figure 29. If, however, the vehicle
manufacturer has opted to use a vehicle-specific feature (as defined in Paragraph
6.2.5.1.) where the nearest TPRD is located on the side of the container (and not on
the axis) and the diameter of the cylinder is larger than the width of the burner, then,
as illustrated in Case 2 of Figure 29, the burner is turned so that the extension of the
engulfing burner is aimed toward the (nearest) TPRD.

Figure 29
Top View Showing Extension of the Engulfing Fire Zone
Toward the Nearest TPRD on a Cylinder
Figure 30 deals with a container that projects a significant planar area where the
width/diameter is larger than the width of the burner. This configuration, for example, is
possible with conformable containers where the vehicle manufacturer has opted to
include vehicle-specific features (as defined in Paragraph 6.2.5.1.) to install the CHSS
under the floor of a vehicle and the CHSS is oriented to evaluate fire exposure to the
bottom of the container based on a pool fire under the vehicle. For this case, the
localized burner is located in the corner opposite the TPRD in order to maximize the
distance from the TPRD and the localized burner zone without extending beyond the
corner.
Since the engulfing fire zone extends on an angle towards the TPRD, the localized
burner is allowed to rotate so it aligns with the extension of the engulfing fire zone. The
maximum extension from the localized burner zone is1,400 ± 50mm, and the burner
can extend beyond the TPRD if the distance from the localized burner to the TPRD is
less than the maximum allowable extension.

Figure 31
Placement of Localized and Engulfing Fire Zones
with TPRDs on Both Ends of a Cylinder
Like in Case 2 of Figure 29, Figure 32 deals with a container where the width/diameter
is greater that the width of the burner, and TPRDs are located on either side of the
cylinder on the walls. This situation can occur by either rotation of the cylinder to the
worst-case position or as a result of the vehicle manufacturer opting for test of a vehiclespecific
protection features. Since the distance to either of the TPRDs are equal, the
burner can be rotated towards either TPRD as the result should be equivalent.

Figure 33
Bottom View Showing Placement of Localized and Engulfing Fire
Zones with TPRDs on Both Ends of Conformable Container
(c)
If the container in the CHSS uses additional (or different locations of) TPRDs or sense
points for protection than addressed in Items (a) and (b) above, then the localized fire
zone is located to maximize the distance to any TPRD, and the engulfing fire zone
extends from one end of the localized zone toward the nearest TPRD up to the
maximum engulfing burner extension defined above.
The process is illustrated in Figure 34 for a cylinder with a TPRD on the left end and a
second TPRD part way along the length of the container. The localized burner is
located under right-side end of the container to maximize the distance from the nearest
TPRD (without extending beyond the spherical head). The engulfing burner extends to
the left (toward the TPRDs) to the maximum allowable of nominally 1,400 ± 50mm.
Additionally, as discussed in (a) above and illustrated in Case 2 of Figure 29, the
extension of the engulfing burner should be turned so that the extension is aimed
toward the nearest TPRD if the width/diameter of the CHSS test article is larger the
burner width.

111. The test is completed after the CHSS vents and the pressure falls to less than 1MPa within
1h for CHSS of LDV or 2h for CHSS of HDV without rupture of the container. The time limits
were conservatively set to account for long-lasting battery and garage fires to provide
adequate time for gaseous contents of the CHSS to be vented when the container is thermally
protected by coatings and shields. The value for the minimum pressure was selected such
that the risk of container rupture was minimal due to stress rupture, and the values for the
time-out of the test are based on vehicle test data. In order to minimize the hazard, jet flames
from venting through the container walls or joints are permitted only as long as any jet flames
do not exceed 0.5m. If venting occurs though the TPRDs, the venting is required to be
continuous, indicating that the TPRD and/or the vent lines are not experiencing periodic flow
blockages which could interfere with proper venting in some situations.
112. If the CHSS fire test in Paragraph 6.2.5.7. times out, then the CHSS fails the test. The gaseous
contents of the CHSS should be vented to eliminate the potential for high energy gas releases
during post-test handling, and the CHSS should be purged with inert gas before ambient air
is able to enter the container and potentially form a flammable gas within the CHSS.
113. The following information is suggested to be provided by the test laboratory along with the
final determination of the result (PASS or FAIL) of the CHSS fire test based on criteria in
Paragraph 5.1.4.:
(a)
(b)
Diagrams and photographs showing the physical arrangement of the burner, container
assembly, and test setup;
Fuel flow and HRR/A during the test;
(c) Temperature readings of the flame monitors (TB and TB ) at 10s intervals and
the 1min rolling averages of flame monitors (that validate or invalidate the test result);
(d)
(e)
(f)
Pressure level within the container during the test;
Ambient temperature and wind speed and direction if outdoor test;
Timeline of significant events leading to final determination of the result.

118. Fuel flow shut-off by an automatic shut-off valve mounted on a compressed hydrogen storage
container shall be fail-safe. The term "fail safe" refers to a device that reverts to a safe mode
or a safe complete shutdown for all reasonable failure modes.
119. The electrical tests for the automatic shut-off valve mounted on the compressed hydrogen
storage containers (Paragraph 6.2.6.2.7.) provide assurance of performance with:
(i)
(ii)
over temperature caused by an overvoltage condition; and
potential failure of the insulation between the component's power conductor and the
component casing.
The purpose of the pre-cooled hydrogen exposure test (Paragraph 6.2.6.2.10.) is to verify that
all components in the flow path from the receptacle to the container that are exposed to
precooled hydrogen during fuelling can continue to operate safely.
(f)
Rationale for Paragraph 5.1.6. Labelling
120. The purpose of minimum labelling on the hydrogen storage containers is three-fold:
(i)
(ii)
(iii)
to document the date when the system should be removed from service;
to record information needed to trace manufacturing conditions in event of
on-road failure; and
to document NWP to ensure installation is consistent with the vehicle fuel system and
fuelling interface. Contracting Parties may specify additional labelling requirements.
Since the number of pressure cycles used in qualification under Paragraph 5.1.1.2.
may vary between Contracting Parties, that number shall be marked on each container.
2. Vehicle Fuel System Requirements and Safety Needs
(a)
In-Use Requirements
(i) Fuelling Receptacle Rationale for Paragraphs 5.2.1.1.
121. The vehicle fuelling receptacle should be designed to ensure that the fuelling pressure is
appropriate for the vehicle fuel storage system. Examples of receptacle designs can be found
in ISO 17268, SAE J2600 and SAE J2799. A label shall be affixed close to the fuelling
receptacle to inform the fueler/driver/owner of the type of fuel (liquid or gaseous hydrogen),
NWP and date for removal of storage containers from service. Contracting parties may specify
additional labelling requirements.
(ii)
Rationale for Paragraph 5.2.1.2. Overpressure Protection for the Low Pressure System
122. The hydrogen delivery system downstream of a pressure regulator is to be protected against
overpressure due to the possible failure of the pressure regulator.
(iii)
Rationale for Paragraph 5.2.1.3. Hydrogen Discharge System
a. Rationale for Paragraph 5.2.1.3.1. pressure relief systems

(iv)
Rationale for Paragraph 5.2.1.4. Protection Against Flammable Conditions:
127. Single Failure Conditions. Dangerous situations can occur if unintended leakage of hydrogen
reaches flammable concentrations.
(a)
(b)
Any single failure downstream of the main hydrogen shut off valve shall not result in
any level of hydrogen concentration in air anywhere in the passenger compartment;
Protection against the occurrence of hydrogen in air in the enclosed or semi enclosed
spaces within the vehicle that contain unprotected ignition sources is important.
(i)
(ii)
Vehicles may achieve this objective by design (for example, where spaces are
vented to prevent increasing hydrogen concentrations);
The vehicle achieves this objective by detection of hydrogen concentrations in
air of 2% ± 1.0% or greater, then the warning shall be provided. If the hydrogen
concentration exceeds 3% ± 1.0% by volume in air in the enclosed or semi
enclosed spaces of the vehicle, the main shutoff valve shall be closed to isolate
the storage system.
(c)
The actionable leak percentages were changed for Paragraph 5.2.1.4.3. (Protection
against flammable conditions: single failure conditions) so they do not overlap. Previous
requirement was a warning level is from 1 to 3%, whereas the valve closure level is
2 to 4%, such that overlap exists in the region between 2 and 3%. The new language
(>3.0% issue warning, >4.0% close shut-off valve) eliminates the overlap and adds
clarity.
(v)
Rationale for Paragraph 5.2.1.5. Fuel Leakage
128. Detectable leakage of the hydrogen fuelling line and delivery system is not permitted.
(vi)
Rationale for Paragraph 5.2.1.6. Visual Signal/Warning System
129. A visual signal/warning system is to alert the driver when hydrogen leakage results in
concentration levels at or above 4% by volume within the passenger compartment, luggage
compartment, and spaces with unprotected ignition sources within the vehicle. The visual
signal/warning system should also alert the driver in case of a malfunction of the hydrogen
detection system. Furthermore, the system shall be able to respond to either scenario and
instantly warn the driver. The shut-off signal shall be inside the occupant compartment in front
of and in clear view of the driver. There is no data available to suggest that the warning
function of the signal would be diminished if it is only visual. In case of a detection system
failure, the signal warning light should be yellow. In case of the emergency shut-off of the
valve, the signal warning light should be red.

(e)
(f)
(g)
Rigid fuel lines should be secured such that they shall not be subjected to critical
vibration or other stresses;
The hydrogen fuel system should protect against excess flow in the event of a failure
downstream;
No component of the hydrogen fuel system, including any protective materials that form
part of such components, should project beyond the outline of the vehicle or protective
structure.
(b)
(i)
Post Crash Requirements
Rationale for Paragraph 5.2.2.1. Post-crash Test Leakage Limit
132. Allowable post-crash leakage in Federal Motor Vehicle Safety Standard (FMVSS) 301 (for the
United States of America) and UN Regulation Nos. 94 and 95 are within 6% of each other for
the 60min period after the crash. Since the values are quite similar, the value in UN Regulation
No. 94 of 30g/min was selected as a basis for the calculations to establish the post-crash
allowable hydrogen leakage for this UN GTR.
133. The criterion for post-crash hydrogen leakage is based on allowing an equivalent release of
combustion energy as permitted by gasoline vehicles. Using a lower heating value of
120MJ/kg for hydrogen and 42.7MJ/kg for gasoline based on the US DOE Transportation
Data Book, the equivalent allowable leakage of hydrogen (W ) can be determined as follows
for vehicles with either compressed hydrogen storage systems or liquefied hydrogen storage
systems:
W
H
� 30g/min gasoline leakage �
42.7MJ/kg
120MJ/kg
� 10.7g/min hydrogen leakage
The total allowable loss of hydrogen is therefore 642g for the 60min period following the crash.
134. The allowable hydrogen flow leakage can also be expressed in volumetric terms (V ) at
normal temperature (0°C) and pressure as follows for vehicles with either compressed or
liquid hydrogen storage.
135. As confirmation of the hydrogen leak rate, JARI conducted ignition tests of hydrogen leaks
ranging from 131NL/min up to 1,000NL/min under a vehicle and inside the engine
compartment. Results showed that, while a loud noise can be expected from ignition of the
hydrogen, the sound pressure level and heat flux were not enough (even at a 1,000NL/min
leak rate) to damage the under floor area of the vehicle, release the vehicle hood, or injure a
person standing 1m from the vehicle (SAE Technical Paper 2007-01-0428 "Diffusion and
Ignition Behaviour on the Assumption of Hydrogen Leakage from a Hydrogen-Fuelled
Vehicle").

141. The methodology can also be expanded to allow the use of a non-flammable gas for crash
testing. Helium has been selected as it, like hydrogen, has low molecular weight. In order to
determine the ratio of volumetric flows between helium and hydrogen releases (and thus
establish a required relationship between hydrogen and helium leakage, we assume that
leakage from the compressed hydrogen storage system can be described as choked flow
through an orifice where the orifice area (A) represents the total equivalent leakage area for
the post-crash system. In this case the equation for mass flow is given by:
where
W = C × Cd × A × (ρ × P)
Cd
A
P
is the orifice discharge coefficient,
is the orifice area,
are the upstream (stagnation) fluid density and pressure, and
ρ and C are given by:
ρ = R × T/M
and
C = γ/( (γ + 1)/2)
where
R is the universal gas constant and
T, M, and γ are the temperature, molecular weight, and ratio of specific heats (C /C ) for the
particular gas that is leaking.
Since Cd, A, R , T, and P are all constant for the situation of determining the relationship
between post-crash helium and hydrogen leakage, the following equation describes the flow
ratio on a mass basis.
W /W = C /C × (M /M )
142. Since we can determine the volumetric flow ratio by multiplying the mass flow ratio by the
ratio of molecular weights (M) at constant temperature and pressure conditions are the same.
V /V = C /C × (M /M )

2. Rationale for Paragraph 6.2. (Test procedures for compressed hydrogen storage systems)
147. Most test procedures for hydrogen storage systems derive from test procedures specified in
historical national regulations and/or industry standards. Key differences are the execution of
tests in sequence (as opposed to historical execution of tests in parallel, each on a separate
new container), and slowing of the filling rate in burst testing to correspond to
in-service fuelling rates. In addition, hold times at burst pressure test points have been
extended to 4min. These changes are designed to reduce the sensitivity of initial burst
measurements to the fuelling rate and to evaluate capability to sustain pressure. An
evaluation of the sufficiency and stringency of requirements in this UN GTR document
compared to historical EU requirements is given in Transport Research Laboratory Project
Report RPN1742 "Hydrogen-Powered Vehicles: A Comparison of the European Legislation
and the draft ECE global technical regulation" by C. Visvikis.
(a)
(b)
Due to the various speeds at which a hydraulic cycle may be performed, a provision
has been added for container manufacturers to specify a pressure cycle profile
(Paragraph 6.2.3.2.). This will prevent the premature failure of the container due to test
conditions outside of the design envelope while still maintaining the stringency of the
tests.
The drop test procedure has been streamlined such that only one container will be
dropped once. The container shall withstand the one drop out of any impact orientations
specified in the test procedure.
148. Requirements for closures of the hydrogen storage system (TPRD, automatic shutoff valve
and check valve) have been developed by and published in CSA/ANSI HGV 3.1 and
CSA/ANSI HPRD 1.
(a)
(b)
(c)
(d)
Evaluations of cycling durability at 50,000 cycles (Paragraph 6.2.6.2.3.) reflect multiple
pressure pulses against check valves during fuelling and multiple operations of
automatic shut-off valves between fuellings;
Vibration tests (Paragraph 6.2.6.2.8.) were designed to scan frequencies from 10 to
40Hz because several component testing facilities reported that there can be more than
one resonant frequency. The frequency of 17Hz used historically in component
vibration tests was established through demonstration of one vehicle traveling over a
variety of road surfaces, and it reflects the influence of engine proximity. However, it is
expected that the resonant frequency could change based upon the component design
and mounting provisions, so to ensure the most severe condition is identified, a sweep
to 40Hz is required;
Results of closure tests are to be recorded by the testing laboratory and made available
to the manufacturer. In the flow rate test, the flow rate is recorded as the lowest
measured value of the eight pressure relief devices tested in NL per minute (0°C and
1 atmosphere) corrected for hydrogen;
The atmospheric exposure test (Paragraph 6.2.6.2.6.) derives from two historical tests.
The oxygen ageing test was contained in CSA/ANSI NGV 3.1 and harmonised with
ISO 12619-2 ("Road vehicles – Compressed gaseous hydrogen (CGH2) and
hydrogen/natural gas blends fuel system components – Part 2: Performance and
general test methods") and ISO 15500-2 (“Road vehicles – Compressed natural gas
(CNG) fuel system components – Part 2: Performance and general test methods”). The
ozone resistance test requirements and test procedure were drawn from Regulation
No. 110 requirement for CNG components, and has been added to both the hydrogen
and CNG components documents at CSA;

G. OPTIONAL REQUIREMENTS: VEHICLES WITH LIQUEFIED HYDROGEN STORAGE
SYSTEMS/RATIONALE
149. Since hydrogen-fuelled vehicles are in the early stages of development and commercial
deployment, testing and evaluation of test methods to qualify vehicles for on road service has
been underway in recent years. However, liquefied hydrogen storage systems (LHSS) have
received considerably less evaluation than have compressed gas storage systems. At the
time of the development of this document, an LHSS vehicle has been proposed by only one
manufacturer, and on-road vehicle experience with LHSS is very limited. The proposed LHSS
requirements in this document have been discussed on a technical basis, and while they
seem reasonable, they have not been validated. Due to this limited experience with LHSS
vehicles, some Contracting Parties have requested more time for testing and validation.
Therefore, the requirements for LHSS have been presented in Section G as optional.
1. Background Information for Liquefied Hydrogen Storage Systems
(a)
Hydrogen Gas has a Low Energy Density Per Unit Volume
150. To overcome this disadvantage, the liquefied hydrogen storage system (LHSS) maintains the
hydrogen at cryogenic temperatures in a liquefied state.
(b) A Typical Liquefied Hydrogen Storage System (LHSS) is Shown Figure 36
151. Actual systems will differ in the type, number, configuration, and arrangement of the functional
constituents. Ultimately, the boundaries of the LHSS are defined by the interfaces which can
isolate the stored liquefied (and/or gaseous) hydrogen from the remainder of the fuel system
and the environment. All components located within this boundary are subject to the
requirements defined in this Section while components outside the boundary are subject to
general requirements in Section 4. For example, the typical LHSS shown in Figure 36 consists
of the following regulatory elements:
(a)
(b)
(c)
(d)
(e)
Liquefied hydrogen storage container(s);
Shut off devices(s);
A boil-off system;
Pressure Relief Devices (PRDs);
The interconnecting piping (if any) and fittings between the above components.

(f)
Malfunction
155. In case of malfunction of the boil-off system, vacuum failure, or external fire, the hydrogen
storage container(s) are protected against overpressure by two independent Pressure Relief
Devices (PRDs) and the vacuum jacket(s) is protected by a vacuum jacket pressure relief
device.
(g)
When Hydrogen is Released to the Propulsion System, it Flows from the LHSS Through
the Shut-off Valve that is Connected to the Hydrogen Fuel Delivery System
156. In the event that a fault is detected in the propulsion system or fuelling receptacle, vehicle
safety systems usually require the container shut-off valve to isolate the hydrogen from the
down-stream systems and the environment.
2. Rationale for Liquefied Hydrogen Storage System Design Qualification Requirements of
Paragraph 7.2.
157. The containment of the hydrogen within the liquefied hydrogen storage system is essential to
successfully isolating the hydrogen from the surroundings and down-stream systems. The
system-level performance tests in Paragraph 7.2. were developed to demonstrate a sufficient
safety level against rupture of the container and capability to perform critical functions
throughout service including pressure cycles during normal service, pressure limitation under
extreme conditions and faults, and in fires.
158. Performance test requirements for all liquefied hydrogen storage systems in on-road vehicle
service are specified in Paragraph 7.2. These criteria apply to qualification of storage systems
for use in new vehicle production.
159. This section (specifies the rationale for the performance requirements established in
Paragraph 7.2. for the integrity of the liquefied hydrogen storage system. Manufacturers are
expected to ensure that all production units comply with the requirements of performance
verification testing in Paragraphs 7.2.1. to 7.2.4.
(a) Rationale for Verification Tests for Baseline Metrics for LHSSs Paragraph 7.2.1.
160. A proof pressure test and a baseline initial burst test are intended to demonstrate the structural
capability of the inner container.
(i) Rationale for Proof Pressure Requirement in Paragraphs 7.2.1.1. and 7.4.1.1.
161. By design of the container and specification of the pressure limits during regular operation
and during fault management (as demonstrated in Paragraphs 7.4.2.2. and 7.4.2.3.), the
pressure in the inner container could rise to 110% of the Maximum Allowable Working
Pressure (MAWP) during fault management by the primary pressure relief device and no
higher than 150% of MAWP even in "worst case" fault management situations where the
primary relief device has failed and the secondary pressure relief device is required to activate
and protect the system. The purpose of the proof test to 130% MAWP is to demonstrate that
the inner container stays below its yield strength at that pressure.

(iii)
Rationale for Vacuum Loss Requirement Paragraph 7.2.2.3. and Test Procedure of
Paragraph 7.4.2.3.
168. In order to prove the proper function of the pressure relief devices and compliance with the
allowed pressure limits of the liquefied hydrogen storage system as described in
Section G.2.(b) of the preamble and verified in Paragraph 7.2.2.3., a sudden vacuum loss due
to air inflow in the vacuum jacket is considered as the "worst case" failure condition. In contrast
to hydrogen inflow to the vacuum jacket, air inflow causes significantly higher heat input to
the inner container due to condensation of air at cold surfaces and evaporation of air at warm
surfaces within the vacuum jacket.
169. The primary pressure relief device should be a re-closing type relief valve so that hydrogen
venting will cease when the effect of a fault subsides. These valves, by globally-accepted
design standards, are allowed a total pressure increase of 10% between the setpoint and full
activation when including allowable tolerances of the setpoint setting itself. Since the relief
valve should be set at or below the MAWP, the pressure during a simulation of the fault that
is managed by the primary pressure relief device should not exceed 110% of MAWP.
170. The secondary pressure relief device(s) should not activate during the simulation of a vacuum
loss that is managed by the primary relief device as their activation may cause unnecessary
instability and unnecessary wear on the secondary devices. To prove fail-safe operation of
the pressure relief devices and the performance of the second pressure relief device in
accordance with the requirements in Paragraphs 7.2.2.3. and 7.4.2.3., a second test shall be
conducted with the first pressure relief device blocked. In this case, either relief valves or burst
discs may be used, and the pressure is allowed to rise to as high as 136% MAWP (in case of
a valve used as secondary relief device) or as high as 150% MAWP (in case of a burst disc
used as secondary relief device) during the simulation of a vacuum loss fault.
(c)
Rationale for Paragraph 7.2.3. Verification Test for Service-terminating Conditions.
171. In addition to vacuum degradation or vacuum loss, fire also may cause overpressure in
liquefied hydrogen storage systems and thus proper operation of the pressure relief devices
have to be proven in a bonfire test.
(d)
Rationale for Verification of LHSS Components: Pressure Relief Device(s) and Shut off
Valves Paragraph 7.2.4.
(i) Rationale for Pressure Relief Device Qualification Requirements (LHSS) Paragraph 7.2.4.1.
172. The qualification requirements verify that the design shall be such that the device(s) will limit
the pressure of the fuel container to the specified values even at the end of the service life
when the device has been exposed to fuelling/de-fuelling pressure and temperature changes
and environmental exposures. The adequacy of flow rate for a given application is verified by
the hydrogen storage system bonfire test and vacuum loss test requirements (Paragraphs
7.2.3. and 7.4.3.).

179. In the case where liquefied nitrogen is used for the crash, the concentration of helium in the
passenger, luggage, and cargo compartments may be measured during the helium leak test
which is conducted after the crash. It is possible to establish a helium concentration criterion
which is equivalent to 4% hydrogen concentration by volume, but the relationship needs to be
adjusted for the difference in temperature of the gas between the operating LHSS and the
temperature during the helium leak test in addition to accounting for differences in physical
properties. The liquefied hydrogen is stored (and will leak) at cryogenic storage temperatures
(-253°C or 20K), but the system is approximately room temperature (20°C or 293K) for the
leak test. In this case, the equations given in Section F1(a) may used to express the ratio of
helium and hydrogen mass flows is as:
W /W = C /C × (M /M ) × (T /T )
and the ratio of helium and hydrogen volumetric flows as:
V /V = C /C × (M /M ) × (T /T )
where terms are as defined in A 5.2.1.1. applying the volumetric flow ratio as defined above
to account for a system that operates at cryogenic storage conditions but is leak tested at
room temperature to the requirement that there be no greater than 4% by volume of hydrogen
in the actual vehicle, yields a value of approximately 0.8% by volume of helium as the
allowable value for the LHSS post-crash test based on the leakage of gas from the LHSS.
(a)
Rationale for Paragraph 7.5.1. Post-crash Leak Test – Liquefied Hydrogen Storage
Systems (LHSSs)
180. The purpose of the test is to confirm that the leakage from vehicles with LHSSs following the
crash test. During the crash test, the LHSS is filled with either liquefied hydrogen (LH ) to the
maximum quantity or liquefied nitrogen (LN ) to the equivalence of the maximum fill level of
hydrogen by weight (which is about 8% of the maximum liquefied hydrogen volume in the
LHSS) depending which fluid is planned for the crash test. The LN fill of about 8% is required
to simulate the fuel weight for the crash test, and slightly more liquefied nitrogen is added to
accommodate system cooling and venting prior to the test. Visual detection of unacceptable
post-crash leakage as defined in Paragraph 7.5.1.1. may be feasible if the LHSS can be
visually inspected after the crash. When using standard leak-test fluid, the bubble size is
expected to be approximately 1.5mm in diameter. For a localised rate of 0.005mg/s
(216Nml/h), the resultant allowable rate of bubble generation is about
2030 bubbles per minute. Even if much larger bubbles are formed, the leak should be readily
detectable. For example, the allowable bubble rate for 6mm bubbles would be approximately
32 bubbles per minute, thus producing a very conservative criteria if all the joints and
vulnerable parts are accessible for post-crash inspection.
181. If the bubble test is not possible or desired, an overall leakage test may be conducted to
produce a more objective result. In this case, the leakage criteria is the same as that
developed for vehicles with compressed hydrogen storage systems. Specifically, the
allowable hydrogen leakage from the LHSS is 118NL/min or 10.7g/min. The state of flow
leaking from the LHSS may be gaseous, liquid, or a two-phase mixture of both. The leakage
is expected to be in the gaseous state as the piping and shutoff valves downstream of the
container are more vulnerable to crash damage than the highly insulated, double-walled
LHSS container. None-the-less, the post-crash tests prescribed in this document can detect
very small leak sites and thus demonstrate the acceptability even if the leakage in the liquid
state. It is not necessary to address the possibility of a two-phase leak as the flow rate will be
less than that what can occur in the liquid state.

183. In order to accurately determine the allowable reduction in pressure during the leak test, the
change in helium flow with pressure needs to be accounted for. Since the density of helium
(ρ ) varies with pressure, the mass flow of helium during the pressure test will also vary
linearly with pressure as given by:
where
W = P × (W /P ) Equation A.7.5.1-5
W and P are the helium mass flow and pressure during the pressure test and
W and P are the initial values of leak test.
Starting with the ideal gas law,
P V = M × R × T
Equation A.7.5.1-6
where
P
V
M
R
T
is the test pressure,
is the volume of the LHSS,
is mass of the LHSS,
is the helium gas constant on a mass basis, and
is the temperature of the LHSS. Differentiating Equation 6 with time leads to
∂P/∂t = R × T/V × ∂M /∂t
Equation A.7.5.1-7
where
∂P /∂t is the change in pressure during the helium pressure test. Since the change in mass
within the LHSS (∂M /∂t) is equal to the helium mass flow during the test period (W ),
Equation 5 for W can be substituted into Equation 7.
After rearranging terms, the equation becomes
where
∂P/P = R × T/V × (W /P ) × ∂t = (W /M ) × ∂t Equation A.7.5.1-8
M is the initial mass of helium in the LHSS for the pressure test.
Integrating the above differential equation results in expressions for the allowable pressure at
the end of the helium leak test and the corresponding allowable pressure loss over the test
period. The expressions are:
and
where
P = P × exp (-W /M × t ) Equation A.7.5.1-9
ΔP = P × (1 - exp (-W /M × t )) Equation A.7.5.1-10
t
is the period of the test.

185. The above example illustrates how the equations can be used to determine the reduction in
helium pressure over the 60min test period for the leak test. The calculations were repeated
over the likely range of container volume (from 50l to 500l) and typical container pressure
ratings (from 6atm to 9atm gauge) in order to understand the sensitivity of the allowable
pressure drop to key parameters. See Figure 37. Since the allowable pressure drop are above
0.5atm (typically substantially above 0.5atm) for all likely container sizes, it was decided to
adopt a simple criterion of 0.5atm for all containers with a storage capacity greater than 200l
in order to simplify the execution of the leak test and the determination of criteria for the
passing the test. Similarly, a criterion of 2atm was adopted for containers less than or equal
to 100l, and a criterion of 1atm for containers greater than 100l and less than or equal to 200l.
Figure 37
Allowable Pressure Loss During the LHSS Leak Test
186. While the methodology results in straight-forward test method with an objective result from a
commonly-used type of test, it should be noted that the criterion is very conservative in that
the methodology assumes liquid leakage rather than the more likely gaseous leakage from
the piping and valves downstream of the LHSS container. For example, the ratio of hydrogen
gas leakage can be determined using Equation A.7.5.1-2 and the resulting ratio of allowable
helium gas leakage to hydrogen gas leakage is a factor of 5.14 higher than that calculated
assuming liquefied hydrogen leaks.

191. Focus topics for Phase 3 are expected to include:
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
Requirements for material compatibility and hydrogen embrittlement;
Requirements for the fuelling receptacle;
Evaluation of performance-based test for long-term stress rupture proposed in
Phase 1;
Consideration of research results reported after completion of Phase 2 – specifically
research related to hydrogen storage systems, and post-crash safety;
Review CP options to achieve further harmonisation;
Fuel system integrity requirements (careful examination of acceleration/sled test for all
categories and side impact test for HDV as proposed by EC and Korea, respectively.);
Review of Section 7 Vehicles with a liquefied hydrogen storage system;
Improvements of the fire test procedures (Results of the round robin tests, container
withstand criteria, etc.);
Improvements of the test procedures (Station risk assessment issues, remote TPRD,
etc.).
192. The following test procedure will be considered for long-term stress rupture:
(a)
Three containers made from the new material (e.g. a composite fibre reinforced
polymer) shall be burst; the burst pressures shall be within ±10% of the midpoint, BPo,
of the intended application. Then:
(i)
(ii)
(iii)
(iv)
Three containers shall be held at >80% BPo and at 65 (±5)°C; they shall not
rupture within 100h; the time to rupture shall be recorded;
Three containers shall be held at >75% BPo and at 65 (±5)°C; they shall not
rupture within 1,000h; the time to rupture shall be recorded;
Three containers shall be held at >70% BPo and at 65 (±5)°C; they shall not
rupture within one year;
The test shall be discontinued after one year. Each container that has not
ruptured within the one year test period undergoes a burst test, and the burst
pressure is recorded.
(b)
(c)
The container diameter shall be >50% of the diameter of intended application and of
comparable construction. The tank may have a filling (to reduce interior volume) if
>99% of the interior surface area remains exposed;
Containers constructed of carbon fibre composites and/or metal alloys are excused
from this test;

(b)
National and International Standards.
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
(k)
(l)
(m)
(n)
(o)
(p)
ISO 17268:2020 Gaseous Hydrogen Land Vehicle Refuelling Connection Devices;
ISO 23273:2013 Fuel Cell Road Vehicles – Safety Specifications – Protection Against
Hydrogen Hazards for Vehicles Fuelled with Compressed Hydrogen;
ISO 14687:2019 Hydrogen Fuel Quality – Product Specification;
ISO 19880-8:2019 Gaseous Hydrogen – Fuelling Stations – Part 8: Fuel Quality
Control;
ISO 19880-1:2020 Gaseous Hydrogen – Fuelling Stations – Part 1: General
Requirements;
ISO 19881:2018 Gaseous Hydrogen – Land Vehicle Fuel Containers;
ISO 19882:2018 Gaseous Hydrogen – Hydrogen – Thermally Activated Pressure Relief
Devices for Compressed Hydrogen Vehicle Fuel Containers;
SAE J2578_201408 – Recommended Practice for General Fuel Cell Vehicle Safety;
SAE J2600_201510 – Compressed Hydrogen Surface Vehicle Fuelling Connection
Devices;
SAE J2601_202005 – Fuelling Protocols for Light Duty Gaseous Hydrogen Surface
Vehicles;
SAE J2799_201912 – Hydrogen Surface Vehicle to Station Communications Hardware
and Software;
SAE J2719_202003 – Hydrogen Fuel Quality for Fuel Cell Vehicles;
China – GB/T 24548-2009 Fuel Cell Electric Vehicles – Terminology;
China – GB/T 24549-2020 Fuel Cell Electric Vehicles – Safety Requirements;
China – GB/T 24554-2009 Performance Test Methods for Fuel Cell Engines;
China – GB/T 26779-2021 Hydrogen Fuel Cell Electric Vehicle Refuelling Receptacle;
(q) China – GB/T 26990-2011 Fuel Cell Electric Vehicles – Onboard Hydrogen System –
Specifications
(r)
(s)
(t)
China – GB/T 26991-2011 Fuel Cell Electric Vehicles – Maximum Speed – Test
Method;
China – GB/T 29123-2012 Specifications for Hydrogen Fuel Cell Vehicles in
Demonstration;
China – GB/T 29124-2012 Hydrogen Fuel Cell Vehicles Facilities for Demonstration
Specifications;

(j)
(k)
(l)
Korea – Public Notice on Safety Standard on Fuel Storage Systems for Motor Vehicles;
United States – FMVSS 304 (2022) – Compressed Natural Gas Fuel Container
Integrity;
European Union Commission Implementing Regulation (EU) 2021/535, Annex XIV
"Hydrogen System Material Compatibility and Fuelling Receptacle".
(b)
National and International standards:
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
(j)
CSA B51:19 – Boiler, Pressure Vessel, and Pressure Piping Code;
CSA/ANSI HGV 2:21 – Compressed Hydrogen Gas Vehicle Fuel Containers;
CSA/ANSI NGV 2:19 – Compressed Natural Gas Vehicle Fuel Containers;
CSA/ANSI HPRD 1:21 – Thermally Activated Pressure Relief Devices for Compressed
Hydrogen Vehicle Fuel Containers;
CSA/ANSI HGV 3.1-2015 (R2019) – Fuel System Component for Hydrogen Gas Power
Vehicles;
ISO 13985:2006 – Liquid Hydrogen – Land Vehicle Fuel Tanks;
ISO 15869:2009 – Gaseous Hydrogen and Hydrogen Blends – Land Vehicle Fuel
Tanks (Technical Specification);
ISO 19881:2018 Gaseous Hydrogen – Land Vehicle Fuel Containers;
SAE J2579_201806 – Standard for Fuel Systems in Fuel Cell and Other Hydrogen
Vehicles;
China – QC/T 816-2009 Hydrogen Supplying and Refuelling Vehicles – Specifications.
K. BENEFITS AND COSTS
194. At this time, the UN GTR does not attempt to quantify costs and benefits for this first stage.
While the goal of the UN GTR is to enable increased market penetration of HFCVs, the
resulting rates and degrees of penetration are not currently known or estimable. Therefore, a
quantitative cost-benefit analysis was not possible.
195. Some costs are anticipated from greater market penetration of HFCVs. For example, building
the infrastructure required to make HFCVs a viable alternative to conventional vehicles will
entail significant investment costs for the private and public sectors, depending on the country.
Especially in the early years of HFCV sales, individual purchasers of HFCVs are also likely to
face greater costs than purchasers of conventional gasoline or diesel vehicles, the same goes
for manufacturers of new HFCVs (However, costs incurred by HFCV purchasers and
manufacturers would essentially be voluntary, as market choice would not be affected).

L. INTEROPERABILITY CONSIDERATIONS
1. Principal Interoperability Elements
198. Hydrogen-fuelled vehicle safety depends on the hydrogen dispenser operation and the
Hydrogen Fuelling Station (HFS) controls during the vehicle fuelling process. It is thus
important to highlight the considerations critical for understanding and taking into account
interoperability between HFS and a hydrogen-fuelled vehicle.
199. Figure 38 below describes an example of the key components of the fuelling station dispenser
including the hydrogen-fuelled vehicle high pressure hydrogen system, comprising among
others, the receptacle and Compressed Hydrogen Storage Systems (CHSS) with sensors as
well as pressure relief device(s). CHSS has a thermally activated pressure relief device(s) to
protect against overpressure due to a fire. On the station side, there is an automated
dispensing control system (e.g. through a Programmable Logic Controller) for performing the
fuelling (using an acceptable fuelling protocol such as SAE J2601), as well as fault detection
and management procedures. The station also has an over pressure protection device such
as a pressure relief device(s) or equivalent to protect against over pressurization of the
dispenser and the vehicle.
Figure 38
Example of the Fuelling Station Dispenser Key Components
including the Vehicle High-Pressure Hydrogen System
200. The dispenser at a public fuelling station for light duty vehicles is typically designed with
separate nozzles to fuel vehicles to 35MPa and/or 70MPa nominal working pressures. The
station fuelling nozzle may contain a communications receiver and the vehicle may contain a
communications transmitter (such as SAE J2799). The vehicle’s Infrared Data Association
(IrDA) communications system may use the SAE J2799 protocol to transmit the measured
temperature and pressure of the compressed hydrogen storage system on the vehicle to the
hydrogen dispenser. The station dispenser controller may use this data for the control system
to manage the fuelling process.

4. Validation of the Fuelling Protocol and Vehicle-to-Station Communication
208. It is important that the fuelling station be validated to demonstrate that it is correctly applying
the fuelling protocol and vehicle-to-station communications. This validation can be conducted
through the use of Factory Acceptance Tests, through the use of Site Acceptance Tests, or a
combination of both. For validation of fuelling stations employing SAE J2601 and SAE J2799,
an approved validation standard, such as CSA/ANSI HGV 4.3, HYSUT-G 0003 or the "CEP
hydrogen fuelling validation test protocol", should be used.
209. Validation of the fuelling protocol is intended to test that the dispenser is:
(a)
(b)
(c)
Applying the control parameters correctly;
Responding to process limit violations correctly;
Able to meet a certain level of fuelling performance (i.e. completing fills without
exceeding process limits and achieving an acceptable ending SOC in the CHSS.
210. Validation of the vehicle-to-station communications is intended to test that the dispenser:
(a)
(b)
(c)
(d)
Receives and interprets the communicated data correctly;
Responds correctly to data values which are outside the allowed bounds;
Responds correctly to bad data packets;
Responds properly to data which should terminate the fill:
(i)
(ii)
(iii)
An "abort" command;
CHSS gas temperature equal to or greater than 85°C;
CHSS SOC ≥100%.

3. Rationale for Environmental Test Condition (Paragraph 221)
215. Rationale for gas purity. Small amounts of gas impurities (especially oxygen) can have
significant effects on properties measured in gaseous hydrogen. Oxygen (and other species)
can adsorb on the specimen surfaces and prevent hydrogen from penetrating the test
specimen within the time scale of the test. While the effects of impurities have not been widely
studied for tensile and fatigue life tests, fatigue crack growth testing shows unambiguous
effects of oxygen on measured fatigue crack growth rates (B.P. Somerday, P. Sofronis, K.A.
Nibur, C. San Marchi, and R. Kirchheim, "Elucidating the variables affecting accelerated
fatigue crack growth of steels in hydrogen gas with low oxygen concentrations",
Acta Mater 61 (2013) 6153–6170). To minimize the influence of purities, the test volume must
be effectively purged to ensure that air is removed from the test environment. It is generally
observed that the test environment and the sampled gas are not as "clean" as the source gas.
Therefore, the test gas must be measured periodically to ensure that the adequate purging
processes are maintained. Verification of the quality of the test gas shall be measured at least
once every 12 months, consistent with standard practice for verification of transducers in test
systems. Allowance for additional impurities (relative to the source gas) are made in Table 6
since purging can never remove all of the oxygen and water. The requirements in Table 6 are
consistent with the requirements in the CSA/ANSI CHMC 1 standard (Test Methods for
Evaluating Material Compatibility in Compressed Hydrogen Applications).
216. Rationale for test pressure. The minimum test pressure shall be 1.25 x NWP to ensure that
pressure effects are captured and representative of maximum service pressure during normal
operation. Testing at higher pressure (>1.25NWP) can be used – for example, data from tests
at pressure of 100MPa can be used to qualify materials in a system with NWP of 70MPa,
since the test pressure must be ≥87.5MPa. While proof testing may be performed at pressure
up to 1.5 x NWP and off-normal conditions could also expose materials to pressure up to
1.5 x NWP, the difference in hydrogen effects between 1.25 x NWP and 1.5 x NWP will
generally be insignificant (H. Kobayashi, T. Yamada, H. Kobayashi, S. Matsuoka, "Criteria for
selecting materials to be used for hydrogen refuelling station equipment", PVP2016-64033,
Proceedings of the ASME 2016 Pressure Vessels and Piping Division Conference,
Vancouver, British Columbia, Canada, 17–21 July 2016). Therefore, for consistency with
normal operating conditions and the fatigue testing, the test pressure for SSRT testing is
specified at 1.25 x NWP.
217. Rationale for test temperature. The environmental temperature range for the vehicle is
generally considered to be 233K to 358K (-40°C to +85°C). Some materials show a
degradation of tensile ductility near this lower temperature bound; typically, a minimum in
tensile ductility is reported approximately in the range of 200K – 220K (S. Fukuyama, D. Sun,
L. Zhang, M. Wen and K. Yokogawa, "Effect of temperature on hydrogen environment
embrittlement of type 316 series austenitic stainless steels at low temperature", J. Japan Inst.
Met. 67 (2003) 456-459; and L. Zhang, M. Wen, M. Imade, S. Fukuyama, K. Yokogawa,
"Effect if nickel equivalent on hydrogen gas embrittlement of austenitic stainless steels based
on type 316 at low temperatures", Acta Metall. 56 (2008) 3414-342). Therefore, the SSRT
test is specified conservatively at this lower bound (228 ± 5K). Unlike tensile testing, fatigue
properties are generally unaffected or improved at low temperature (J. Schijve, Fatigue of
Structures and Materials, 2 ed., Springer, 2009). This trend has been demonstrated for
testing in gaseous hydrogen as well (T. Iijima, H. Enoki, J. Yamabe, B. An, "Effect of
high-pressure gaseous hydrogen on fatigue properties of SUS304 and SUS316 austenitic
stainless steel", PVP2018-84267, Proceedings of the ASME 2018 Pressure Vessels and
Piping Division Conference, Prague, Czech Republic, 15–20 July 2018); this study also shows
fatigue life in gaseous hydrogen is improved at elevated temperature up to 80°C. Therefore,
fatigue testing is specified at room temperature (293 ± 5K).

5. Test Procedure
220. Materials definition.
(a)
The material under consideration shall be defined by a materials specification – the
specification can be a nationally-recognized standard or a company-defined
specification. The materials specification shall include requirements for the following:
(i)
(ii)
(iii)
(iv)
allowable compositional ranges;
specified minimum tensile yield strength (Sy);
specified minimum tensile strength (Su); and,
specified minimum tensile elongation (El).
(b)
(c)
(d)
The material should be tested in the final product form whenever possible. When the
component geometry precludes extraction of test specimens, the material may be
tested in the semi-finished product form with mechanical properties that are nominally
equivalent to the mechanical properties of the component;
Either the materials manufacturer’s certification or equivalent testing performed in air
at room temperature may be used to verify that the material meets the specification.
The measured tensile strength is denoted S* (average value from at least two tests at
room temperature in air or from the mill certification) and is used to define the maximum
stress for fatigue testing;
Welds and metallurgically-bonded materials:
(i)
(ii)
(iii)
(iv)
When materials are welded (or metallurgically-bonded) and the joint is exposed
to gaseous hydrogen, weld specimens shall be tested in conjunction with the
base materials for hydrogen compatibility;
Welds and metallurgically-bonded materials shall be defined by a welding
procedure specification (WPS) that defines the joining procedure as well as the
composition and specified minimum tensile requirements (Sy, Su and El) of the
joined structure (e.g. weld metal);
Test specimens should be extracted from the joined structure whenever
possible. Representative joints can be prepared, if test specimens cannot be
extracted from the joined structure;
Weld test specimens shall be measured in gaseous hydrogen and shall satisfy
the requirements of WPS as well as the testing requirements in Paragraph 222.

222. Testing requirements
(a)
The requirements for either the notched specimen methodology (Option 1) or the
smooth specimen methodology (Option 2) shall be satisfied. It is not necessary to
satisfy both the notched and smooth methods.
(b) Notched specimen methodology (Option 1)
(i)
Notched bar specimens shall be used with an elastic concentration factor (Kt) of
greater than or equal to 3. A minimum of three specimens shall be tested in the
environmental conditions described in Paragraph 221.
a. Force-controlled fatigue life tests shall be performed with a constant load
cycle in accordance with internationally-recognized standards. The stress
at maximum load during fatigue cycling shall be greater than or equal to
1/3 of S* (the average tensile strength measured at room temperature in
air). The stress is defined as the load divided by the net-section stress
(i.e. minimum initial cross sectional area of the specimen). The load ratio
(R) shall be 0.1, where R = S /S (S is the minimum net-section
stress and S is the maximum net-section stress;
b. The frequency shall be 1Hz or lower.
(ii)
Requirement for notched specimen methodology:
a. For notched-specimen fatigue testing, the number of applied cycles (N)
shall be greater than 10 cycles for each tested specimen.
(c) Smooth specimen methodology (Option 2)
(i)
Smooth fatigue specimens shall be used in accordance with internationallyrecognized
standards. A minimum of three specimens shall be tested in the
environmental conditions described in Paragraph 221.
a. Force-controlled fatigue life tests shall be performed with a constant load
cycle in accordance with internationally-recognized standards. The stress
at maximum load during fatigue cycling shall be greater than or equal to
1/3 of S* (the average tensile strength measured at room temperature in
air). The stress is defined as the load divided by the net-section stress
(i.e. minimum initial cross sectional area of the specimen). The load ratio
(R) shall be -1 (fully reversed tension-compression load cycle), where
R = S /S (S is the minimum net-section stress and S is the
maximum net-section stress;

N. HUMID GAS STRESS CORROSION CRACKING TESTING FOR ALUMINIUM ALLOYS
1. Introduction
224. Compressed hydrogen storage and containment systems must be compatible with gaseous
hydrogen over the entire applicable pressure and temperature ranges. Hydrogen
embrittlement is a major problem for materials used in these systems. Aluminium alloys show
good hydrogen embrittlement resistance and are possible materials for this system. However,
some types of aluminium alloys show Stress Corrosion Cracking (SCC) in humid gas
conditions. The difference between the mechanisms of anodic dissolution type (SCC) and
Humid Gas SCC (HG-SCC) is shown in Figure 39.
Figure 39
Mechanisms of SCC in a Humid Gas Environment
225. The vessel is generally exposed to humid conditions on the outside and also is in contact with
water as an impurity in hydrogen gas on the inside. Therefore, this type of SCC occurs both
outside and inside of containers under the presence of water. The crack growth test by
constant load or constant displacement method is intended to demonstrate that the materials
show adequate SCC resistance for anticipated service conditions.

4. Rationale for Testing Requirements
231. Test specimen (Paragraphs 237(a), (b)). Specimens for this test were cut from the wrought
aluminium alloy products (plate, extruded and forged products), It is recommended that
compact specimens (CS), or single edge bend (SE) specimens be used for this test. The
geometry of the compact specimen and single edge bend specimen are shown in
ISO7539-6:2011 and ASTM E399-20a.
Net width W and thickness B shall be measured within an accuracy of 0.1% of W along a line
existing within 10% of W from the crack plane.
The face of specimen shall be processed to make the crack detectable and its length
measurable.
232. Fatigue pre-crack (Paragraph 237(c)). Fatigue pre-crack shall be introduced at room
temperature in the atmospheric condition. Effective crack length a including the fatigue
pre-crack shall fulfil the following equation for small scale yielding as specified in B.5 of
ISO 7866:2012.
Where:
a, (W-a) ≥ 1270(K )
a: effective crack length (distance between fatigue pre-crack tip and load axis (mm))
W: specimen actual net width (mm)
K
: stress intensity factor of a crack when a load was applied to the specimen (MPa�m)
233. Applied load and measurement (Paragraphs 237(d), (e)). Both constant load condition and
constant displacement condition are permitted in this test. A constant load condition is
preferable to a constant displacement condition in this test. However, there appears to be no
difference in both condition when cracks do not propagate.
If the monitored load is less than 95% if applied load P, the test specimen should be rejected
without waiting for the final qualification of materials. Studies by Japanese academic
researchers show that the crack length extension by HG-SCC exceeds 0.16mm when the
threshold load decreases to less than 95% of applied load P.
234. Acceptance Criterion (Paragraph 239). The crack extension by HG-SCC is examined to
determine if it exceeds 0.16mm within the 90-day test period. This value means that crack
growth rate is less than 2 x 10 m/s and is lower than general SCC criteria of 10 m/s.

(c) Fatigue pre-crack shall be introduced in accordance with Class 6 of ISO 7539-6:2018;
(d)
A load is applied under constant load or constant displacement conditions:
(i)
(ii)
For the constant load condition, it is necessary to use a testing machine capable
of load accuracy control within ±1% of the load applied, as defined in 7.6.3 of
ISO 7539-6:2011;
For the constant displacement condition, the sensitivity of the displacement
gauge shall be not less than 20mV/mm as to minimize the excess amplification
of small signals. The linearity of the gauge is such that the deviation from the
true displacements shall not exceed 3μm (0.003mm) for smaller displacements
up to 0.5mm and not exceed 1% of recorded values for larger displacements.
These conditions are in accordance with 7.5.3 of ISO 7539-6:2011;
(iii)
The load is the value of K
obtained by the following equation from B.6.2 of
ISO 7866:2012.
K = 0.056�
(e)
Measurement of load: For constant displacement condition, the load shall be measured
by one of the following methods after the 90-day test period:
(i)
When the load is not monitored:
a. At the end of the test, the crack mouth opening displacement is measured
before removal of the load;
b. The load is removed;
c. The load is reapplied until the crack mouth opening displacement attains
the value in a. with a load measuring instrument.
(ii)
When the load is monitored, the load at the end of the test is measured. It is also
acceptable to calculate the load value from the values of elastic strain measured
between the start and the end of the test.
(f)
Fatigue post-cracking and breaking shall be introduced as follows:
(i)
(ii)
For a constant load condition, a fatigue post-crack is introduced until the postcrack
length is extended to 1mm or more by applying a fatigue load equivalent
to a stress intensity factor not exceeding 0.6 times the value of K obtained by
loading;
For a constant displacement condition, after the load measurement is performed
per (e) above, the load is removed, and a fatigue post-crack is introduced until
the post-crack length is extended to 1mm or more by applying a fatigue load
equivalent to a stress intensity factor not exceeding 0.6 times the value of K
obtained in (e) above.
After the introduction of a fatigue post-crack the specimen shall be broken open. If it is
possible to identify the HG-SCC fracture surface, the specimen may be broken by a
method other than the introduction of a fatigue post-crack;

239. Acceptance Criterion
The applicability of materials shall be judged as follows:
(a) The crack extension (a - a ) by HG-SCC in Paragraph 238. is examined to
determine if it exceeds 0.16mm;
(b) The actual applied value of K , defined as K , is calculated by using a and the load
applied according to Paragraph 237.(d)(i) for constant-load condition and
Paragraph 237.(d)(ii) for constant-displacement condition;
(c)
The validity of materials is judged as per Table 8 below.
Table 8
Qualification of Materials
Case
Crack Extension
K
Versus K
Judgment*
I
K
≥K
Pass
II
(a
– a
) ≤0.16mm
K
Invalid
III
K
≤K
Fail
IV
(a
– a
) >0.16mm
K
>K
Invalid
Material shall be judged as follows:
Pass:
Fail:
Invalid:
Materials that satisfy this requirement are judged to have applicable
resistance to HG-SCC for compressed hydrogen containers as specified in
B.7.3 of ISO 7866:2012.
Materials are judged to be failed for application for compressed hydrogen
containers.
Materials cannot be judged in these conditions.
In Case II, another test is recommended if K equals to K or is in some degree
greater than K .
In Case IV, where K is considerably greater than K , another test is recommended
because materials may pass if K is a little greater than K .
(d)
A minimum of three valid specimens shall meet the "passed" judgment in this test.

Table 10
Optional Tolerances for Test Parameters
Paragraph Test Parameter Value
Pressure
6.2.2.
6.2.3.
6.2.6.
Optional
Tolerance
Unit
Target pressure ≥ or ≤ various per cent NWP 5 per cent NWP
6.2.4. Target pressure ≥100% SOC 5 per cent SOC
6.2.4.
6.2.6.1.1.
6.2.6.1.3.(c)
6.2.6.1.11.(a)
6.2.6.2.6.(a)
6.2.6.2.3.(b)(i)
Temperature
6.2.3.
6.2.4.
6.2.6.1.1.
6.2.6.1.3.(a)(c)(d)
6.2.6.2.3.(a)(i)
6.2.6.2.3.(a)(iii)
6.2.6.1.8.
6.2.6.2.2.
6.2.6.1.11.(a)
6.2.6.2.6.(a)
Humidity
6.2.3.6.(c)
6.2.4.
6.2.6.1.4.
6.2.6.2.4.
6.2.6.1.4.
6.2.6.2.4.
6.2.6.1.4.
6.2.6.2.4.
Initial pneumatic
pressure
Atmospheric
exposure pressure
Post-chatter flow
cycle pressure
≤2MPa 1 MPa
2MPa +0.2/-0 MPa
≤60% NWP 60 per cent NWP
Temperature ≥ or ≤ various °C 10 °C
Temperature cycling / ≥85°C
pressure cycling ≤ -40°C
extreme temperatures
Leak test temperature ≥85°C
≤-40°C
5 °C
3 °C
Atmospheric
70°C
±1
°C
exposure temperature
Hot phase humidity ≥80% RH 20 per cent RH
Dry-off apparatus
humidity
Humid stage cycle
humidity
Dry stage cycle
humidity
≤30% RH 30 per cent RH
100% RH +0/-20 per cent RH
≤30% RH 30 per cent RH

Paragraph Test Parameter Value
Optional
Tolerance
6.2.6.2.7.(a)(ii) 2nd test hold time at least 1min 5 s
6.2.6.2.7.(b)
6.2.6.1.6.
6.2.6.2.9.
Rates
Insulation resistance
test voltage
application time
Ammonia-air
exposure time
at least 2s 1 s
at least 10 days 2 h
6.2.4.1. (b)
Fuelling ramp rate
greater than or equal to the
ramp rates given in
the SAEJ2601_202005
fuelling tables
6.2.4.1.(d)
De-fuelling rate
greater than or equal to
the intended vehicle’s
maximum fuel-demand rate
6.2.4.1.(d)
De-fuelling rate
greater than or equal to the
maintenance de-fuelling rate
Voltage
Unit
7 MPa/min
-0/+100% of
the rate
-0/+100% of
the rate
6.2.6.2.7.(a)(i) 1st test voltage ≥1.5 times rated voltage 0.5 V
6.2.6.2.7.(a)(ii) 2nd test voltage ≥2 times rated voltage 0.5 V
6.2.6.2.7.(b)
Distance
6.2.3.2.(a)(i)
Insulation resistance
test voltage
Horizontal drop
height
1000V DC ±10 V
1.8m ±0.02 m
6.2.3.2.(a)(ii)(iii) Vertical drop height calculated drop height ±0.02 m
6.2.3.2.(a)(iv)
45° angle centre of
gravity height
≤1.8m 0.04 m
6.2.3.3.(a) Cut 1 depth at least 0.75mm 0.5 mm
6.2.3.3.(a) Cut 1 length at least 200mm 5 mm
6.2.3.3.(a) Cut 2 depth at least 1.25mm 0.5 mm
6.2.3.3.(a) Cut 2 length at least 25mm 1 mm
6.2.3.3. (b) Pendulum impact
area diameters
6.2.3.3. (b) Pendulum impactor
edge radius
100mm ±10 mm
3mm ±1 mm
6.2.6.1.7.(a) Drop height ≥2m 0.05 m
g/s or NL/min
g/s or NL/min

II.
TEXT OF THE REGULATION
1. PURPOSE
2. SCOPE
This regulation specifies safety-related performance requirements for hydrogen-fuelled
vehicles. The purpose of this regulation is to minimise human harm that may occur as
a result of fire, burst or explosion related to the vehicle fuel system.
2.1. This regulation applies to all hydrogen-fuelled vehicles of Categories 1 and 2 with a
maximum design speed exceeding 25km/h.
2.2. Contracting Parties may exclude the following vehicles from the application of this
regulation:
(a)
(b)
A vehicle with four or more wheels whose unladen mass is not more than 350kg,
not including the mass of traction batteries, whose maximum design speed is not
more than 45km/h, and whose engine cylinder capacity and maximum
continuous rated power do not exceed 50cm for spark (positive) ignition engines
and 4kW for electric motors respectively; and
A vehicle with four or more wheels, other than that classified under (a) above,
whose unladen mass is not more than 450kg (or 650kg for vehicles intended for
carrying goods), not including the mass of traction batteries and whose maximum
continuous rated power does not exceed 15kW.
3. DEFINITIONS
3.1. (vacant)
3.2. (vacant)
For the purpose of this regulation, the following definitions shall apply:
3.3. "Burst disc" is the non-reclosing operating part of a pressure relief device which, when
installed in the device, is designed to burst at a predetermined pressure to permit the
discharge of compressed hydrogen.
3.4. "Check valve" is a non-return valve that prevents reverse flow.
3.5. "Hydrogen concentration" is the percentage of the hydrogen moles (or molecules)
within the mixture of hydrogen and air (Equivalent to the partial volume of hydrogen
gas).
3.6. "Container" (for hydrogen storage) is the pressure-bearing component on the vehicle
that stores the primary volume of hydrogen fuel in a single chamber or in multiple
permanently interconnected chambers.
3.7. "Container Attachments" are non-pressure bearing parts attached to the container
that provide additional support and/or protection to the container and that may be only
temporarily removed for maintenance and/or inspection only with the use of tools.

3.26. "High voltage" is the classification of an electric component or circuit, if its maximum
working voltage is greater than 60V and less than or equal to 1,500V of direct current
(DC), or greater than 30V and less than or equal to 1,000V of alternating current (AC).
3.27. "High voltage bus" is the electrical circuit, including the coupling system, for charging
the REESS that operates on high voltage.
3.28. "Hydrogen-fuelled vehicle" indicates any motor vehicle that uses compressed
gaseous or liquefied hydrogen as a fuel to propel the vehicle, including fuel cell and
internal combustion engine vehicles. Hydrogen fuel for the vehicles is specified in ISO
14687:2019 and SAE J2719_202003.
3.29. (vacant)
3.30. (vacant)
3.31. (vacant)
3.32. "Luggage compartment" is the space in the vehicle for luggage and/or goods
accommodation, bounded by the roof, hood, floor, side walls being separated from the
passenger compartment by the front bulkhead or the rear bulkhead.
3.33. "Liquefied hydrogen storage system" indicates liquefied hydrogen storage
container(s) PRDs, shut off device, a boil-off system and the interconnection piping (if
any) and fittings between the above components.
3.34. "Lower flammability limit (LFL)" is the lowest concentration of fuel at which a
gaseous fuel mixture is flammable at normal temperature and pressure. The lower
flammability limit for hydrogen gas in air is conservatively 4% by volume based on
quiescent environment (Paragraph 130 in Part I).
3.35. "Maximum allowable working pressure (MAWP)" is the highest gauge pressure to
which a container or hydrogen storage system is permitted to operate under normal
operating conditions.
3.36. "Maximum fuelling pressure (MFP)" is the maximum pressure applied to
compressed hydrogen storage system during fuelling. The maximum fuelling pressure
is 125% of the Nominal Working Pressure.
3.37. "Nominal working pressure (NWP)" is the gauge pressure that characterises typical
operation of a system. For compressed hydrogen storage system, NWP is the settled
pressure of compressed gas in fully fuelled container at a uniform temperature of 15°C.
3.38. (vacant)
3.39. (vacant)
3.40. "Passenger compartment" is the space for occupant accommodation, bounded by
the roof, floor, side walls, doors, outside glazing, front bulkhead and rear bulkhead or
rear gate.

3.52. "State of charge (SOC)" means the density ratio of hydrogen in the CHSS between
the actual CHSS condition and that at NWP with the CHSS equilibrated to 15°C. SOC
is expressed as a percentage using the formula:
The density of hydrogen at different pressure and temperature are listed in the Table 1
below.
Table 1
Compressed Hydrogen Density (g/l)
Temperature
(°C)
Pressure (MPa)
1 10 20 30 35 40 50 60 65 70 75 80 87.5
-40
1.0
9.7
18.1
25.4
28.6
31.7
37.2
42.1
44.3
46.1
48.4
50.3
53.0
-30
1.0
9.4
17.5
24.5
27.7
30.6
36.0
40.8
43.0
45.1
47.1
49.0
51.7
-20
1.0
9.0
16.8
23.7
26.8
29.7
35.0
39.7
41.9
43.9
45.9
47.8
50.4
-10
0.9
8.7
16.2
22.9
25.9
28.7
33.9
38.6
40.7
42.8
44.7
46.6
49.2

5. PERFORMANCE REQUIREMENTS
5.1. Compressed Hydrogen Storage System
This section specifies the requirements for the integrity of the compressed hydrogen
storage system.
(a)
The primary closure devices shall include the following functions, which may be
combined:
(i)
(ii)
(iii)
TPRD;
Check valve; and
Shut-off valve.
(b)
(c)
Each Contracting Party may, at its discretion, require that the primary closure
devices shall be mounted directly on or within each container:
CHSS shall meet the performance test requirements summarised in Table 2. The
corresponding test procedures are specified in Paragraph 6.
Table 2
Overview of Performance Qualification Test Requirements
Requirement Section
5.1.1. Verification tests for baseline
metrics
5.1.2. Verification test for
performance durability
5.1.3. Verification test for expected
on-road performance
5.1.4. Verification test for service
terminating performance in fire
5.1.5. Verification test for closure
durability
Test Article
Container or container plus container attachments,
as applicable
Container or container plus container attachments,
as applicable
CHSS
CHSS
Primary closure devices
All new compressed hydrogen storage systems produced for on-road vehicle service
shall have a NWP of 70MPa or less.
The service life of CHSS shall be determined by the manufacturer, who shall establish
the date of removal from service taking account of the performance requirements
applied in the respective market.

5.1.2.1. Proof Pressure Test
Figure 1
Verification Test for Performance Durability (Hydraulic)
The container is pressurised in accordance with the procedure specified in
Paragraph 6.2.3.1. The container attachments, if any, shall also be included in this test,
unless the manufacturer can demonstrate that the container attachments do not affect
the test results and are not affected by the test procedure. The container that has
undergone a proof pressure test in manufacture is exempt from this test.
5.1.2.2. Drop (Impact) Test
The container with its container attachments (if any) is dropped once in one of the
impact orientations specified in Paragraph 6.2.3.2.
5.1.2.3. Surface Damage Test
The container with its container attachments (if applicable) is subjected to surface
damage specified in Paragraph 6.2.3.3..
5.1.2.4. Chemical Exposure and Ambient-temperature Pressure Cycling Test
The container with its container attachments (if applicable) is exposed to chemicals
found in the on-road environment and pressure cycled in accordance with
Paragraph 6.2.3.4.
5.1.2.5. High Temperature Static Pressure Test.
The container with its container attachments (if applicable) is pressurised in accordance
with Paragraph 6.2.3.5.

5.1.3.1. Proof Pressure Test
The container of a CHSS is pressurised in accordance with the procedure specified in
Paragraph 6.2.3.1. The container attachments, if any, shall also be included in this test,
unless the manufacturer can demonstrate that the container attachments do not affect
the test results and are not affected by the test procedure. The container that has
undergone a proof pressure test in manufacture is exempt from this test.
5.1.3.2. Ambient and Extreme Temperature Gas Pressure Cycling Test (Pneumatic)
The CHSS is pressure cycled in accordance with Paragraph 6.2.4.1.
5.1.3.3. Extreme Temperature Static Gas Pressure Leak/Permeation Test. (Pneumatic)
The test shall be conducted in accordance with Paragraphs 6.2.4.2. and 6.2.4.3.
The maximum allowable hydrogen discharge from the CHSS is 46ml/h/L water capacity
of the CHSS.
Any single point of localised external leakage measured in accordance with
Paragraph 6.2.4.3. shall not exceed.
5.1.3.4. Residual Proof Pressure Test (Hydraulic)
The container with its container attachments (if any), as specified, is pressurised in
accordance with the procedure specified in Paragraph 6.2.3.1.
5.1.3.5. Residual Strength Burst Test (Hydraulic)
The container with its container attachments (if any), as specified, undergoes a
hydraulic burst. The burst pressure measured in accordance with the procedure
specified in Paragraph 6.2.2.1. shall be at least 80% of the BP provided by the
manufacturer in Paragraph 5.1.1.1.
5.1.4. Verification Test for Service Terminating Performance in Fire
CHSS shall undergo the two-stage localised/engulfing fire test specified in
Paragraph 6.2.5.
During the test, CHSS are filled to 100% state-of-charge (SOC) with compressed
hydrogen as the test gas.
CHSS shall vent to less than 1MPa within 1h for LDV or within 2h for HDV. If venting
occurs from TPRD(s), the venting shall be continuous. The container shall not rupture
during the CHSS fire test. Except for discharges from the exhausts of TPRD vents, any
leakage, permeation, or venting from the CHSS, including through the container walls
or joints, other components, and fittings, shall not result in jet flames greater than 0.5m.
If the CHSS pressure has not fallen below 1MPa when the time limit defined above is
reached, then the CHSS fire test is terminated and the CHSS fails the fire test (even if
rupture did not occur).

5.1.6. Labelling
A label shall be permanently affixed on each container or container attachments with
at least the following information: name of the manufacturer, serial number, date of
manufacture, NWP, type of fuel, and date of removal from service as well as the number
of cycles used in the testing programme as per Paragraph 5.1.1.2. Any label in
compliance with this paragraph shall remain in place and be legible for the duration of
the manufacturer's recommended service life for the container.
Each Contracting Party may, at its discretion, introduce the maximum length of the
service life such that the date of removal from service shall not be more than 25 years
after the date of manufacture.
5.2. Vehicle Fuel System
This section specifies requirements for the vehicle fuel system, which includes the
CHSS, piping, joints, and components in which hydrogen is present.
5.2.1. In-use Fuel System Integrity
5.2.1.1. Fuelling Receptacle Requirements
5.2.1.1.1. A compressed hydrogen fuelling receptacle shall prevent reverse flow to the
atmosphere. Test procedure is in accordance with the leak test specified in
Paragraph 6.2.6.2.2.
5.2.1.1.2. A label shall be affixed close to the fuelling receptacle; for instance, inside a refilling
hatch, showing the following information: fuel type (e.g. "CHG" for gaseous hydrogen),
NWP, MFP, date of removal from service of containers.
5.2.1.1.3. The fuelling receptacle shall be mounted on the vehicle to ensure positive locking of
the fuelling nozzle. The receptacle shall be protected from tampering and the ingress
of dirt and water (e.g. installed in a compartment which can be locked). Test procedure
is by visual inspection.
5.2.1.1.4. The fuelling receptacle shall not be mounted within the external energy absorbing
elements of the vehicle (e.g. bumper) and shall not be installed in the passenger
compartment, luggage compartment and other places where hydrogen gas could
accumulate and where ventilation is not sufficient. Test procedure is by visual
inspection.
5.2.1.2. Over-pressure Protection for the Low Pressure System (Paragraph 6.1.6. Test
Procedure)
The hydrogen system downstream of a pressure regulator shall be protected against
overpressure due to the possible failure of the pressure regulator. The set pressure of
the overpressure protection device shall be lower than or equal to the maximum
allowable working pressure for the appropriate section of the hydrogen system.

5.2.1.6. Tell-tale Signal Warning to Driver
The warning shall be given by a visual signal or display text with the following
properties:
(a)
(b)
(c)
(d)
Visible to the driver while in the driver's designated seating position with the
driver's seat belt fastened;
Yellow in colour if the detection system malfunctions (e.g. circuit disconnection,
short-circuit, sensor fault) and shall be red in compliance with
Paragraph 5.2.1.4.3;
When illuminated, shall be visible to the driver under both daylight and night time
driving conditions;
Remains illuminated when >3.0% concentration or detection system malfunction
exists and the ignition locking system is in the "On" ("Run") position or the
propulsion system is activated.
5.2.2. Post-crash Fuel System Integrity
Each Contracting Party may maintain its existing national crash tests (frontal, side, rear
and rollover) and shall use the limit values of Paragraphs 5.2.2.1. to 5.2.2.3.
5.2.2.1. Fuel Leakage Limit
The volumetric flow of hydrogen gas leakage shall not exceed an average of 118NL
per minute for the time interval, ∆t, as determined in accordance with Paragraph 6.1.1.1
or 6.1.1.2.
5.2.2.2. Concentration Limit in Enclosed Spaces
Hydrogen gas leakage shall not result in a hydrogen concentration in the air greater
than 4.0% by volume in the passenger and luggage compartments (Paragraph 6.1.2.
test procedures). The requirement is satisfied if it is confirmed that the shut-off valve of
the storage system has closed within 5s of the crash and no leakage from the storage
system.
5.2.2.3. Container Displacement
The container(s) shall remain attached to the vehicle at a minimum of one attachment
point.

If the calculated value of Δt is less than 60min, Δt is set to 60min.
The initial mass of hydrogen in the CHSS can be calculated as follows:
P ' = P × 288/(273 + T )
ρ ' = –0.0027 × (P ') + 0.75 × P ' + 1.07
M = ρ ' × V
Correspondingly, the final mass of hydrogen in the CHSS, M , at the end of the time
interval, Δt, can be calculated as follows:
where
P ' = P × 288/(273 + T )
ρ ' = –0.0027 × (P ') + 0.75 × P ' + 1.07
M = ρ ' × V
P
T
is the measured final pressure (MPa) at the end of the time interval, and
is the measured final temperature (°C).
The average hydrogen flow rate over the time interval (that shall be less than the criteria
in Paragraph 5.2.2.1.) is therefore
where
V = (M -M )/Δt × 22.41/2.016 × (P /P )
V
is the average volumetric flow rate (NL/min) over the time interval and the term
(P /P ) is used to compensate for differences between the measured initial
pressure, P , and the targeted fill pressure P .

The average helium flow rate over the time interval is therefore
where
V = (M -M )/Δt × 22.41/4.003 × (P P )
V is the average volumetric flow rate (NL/min) over the time interval and the term
P /P is used to compensate for differences between the measured initial
pressure (P ) and the targeted fill pressure (P ).
Conversion of the average volumetric flow of helium to the average hydrogen flow is
done with the following expression:
where
V = V /0.75
V is the corresponding average volumetric flow of hydrogen (that shall be less than
the criteria in Paragraph 5.2.2.1. to pass).
6.1.2. Post-crash Concentration Test for Enclosed Spaces
The measurements are recorded in the crash test that evaluates potential hydrogen (or
helium) leakage (Paragraph 6.1.1. test procedure).
Sensors are selected to measure either the build-up of the hydrogen or helium gas or
the reduction in oxygen (due to displacement of air by leaking hydrogen/helium).
Sensors are calibrated to traceable references to ensure an accuracy of ±5% at the
targeted criteria of 4% hydrogen or 3% helium by volume in air, and a full scale
measurement capability of at least 25% above the target criteria. The sensor shall be
capable of a 90% response to a full scale change in concentration within 10s.
Prior to the crash impact, the sensors are located in the passenger and luggage
compartments of the vehicle as follows:
(a)
(b)
(c)
At a distance within 250mm of the headliner above the driver's seat or near the
top centre the passenger compartment;
At a distance within 250mm of the floor in front of the rear (or rear most) seat in
the passenger compartment;
At a distance within 100mm of the top of luggage compartment within the vehicle
that are not directly affected by the particular crash impact to be conducted.
The sensors are securely mounted on the vehicle structure or seats and protected for
the planned crash test from debris, air bag exhaust gas and projectiles. The
measurements following the crash are recorded by instruments located within the
vehicle or by remote transmission.
The vehicle may be located either outdoors in an area protected from the wind and
possible solar effects or indoors in a space that is large enough or ventilated to prevent
the build-up of hydrogen to more than 10% of the targeted criteria in the passenger and
luggage compartments.

6.1.3.1.2. Test Method
6.1.3.1.2.1. Preparation for the Test:
The test is conducted without any influence of wind.
(a)
(b)
A test gas induction hose is attached to the hydrogen gas leakage detector;
The hydrogen leak detector is enclosed with a cover to make gas stay around
hydrogen leak detector.
6.1.3.1.2.2. Execution of the Test
(a)
(b)
(c)
Test gas is blown to the hydrogen gas leakage detector;
Proper function of the warning system is confirmed within 10s when tested with
the gas to verify function of the warning;
The main shut-off valve is confirmed to be closed within 10s when tested with
the gas to verify function of the shut-down. For example, the monitoring of the
electric power to the shut-off valve or of the sound of the shut-off valve activation
may be used to confirm the operation of the main shut-off valve of the hydrogen
supply.
6.1.3.2. Test Procedure for Integrity of Enclosed Spaces and Detection Systems.
6.1.3.2.1. Preparation:
6.1.3.2.1.1. The test is conducted without any influence of wind.
6.1.3.2.1.2. Special attention is paid to the test environment as during the test flammable mixtures
of hydrogen and air may occur.
6.1.3.2.1.3. Prior to the test the vehicle is prepared to simulate remotely controllable hydrogen
releases from the hydrogen system. Hydrogen releases may be demonstrated by using
an external fuel supply without modification of the test vehicle fuel lines. The number,
location and flow capacity of the release points downstream of the main hydrogen
shutoff valve are defined by the vehicle manufacturer taking worst case leakage
scenarios under a single failure condition into account. As a minimum, the total flow of
all remotely controlled releases shall be adequate to trigger demonstration of the
automatic "warning" and hydrogen shut-off functions.
6.1.3.2.1.4. For the purpose of the test, a hydrogen concentration detector is installed where
hydrogen gas may accumulate most in the passenger compartment (e.g. near the
headliner) when testing for compliance with Paragraph 5.2.1.4.2. and hydrogen
concentration detectors are installed in enclosed or semi enclosed volumes on the
vehicle where hydrogen can accumulate from the simulated hydrogen releases when
testing for compliance with Paragraph 5.2.1.4.3. (see Paragraph 6.1.3.2.1.3.).

6.1.5. Compliance Test for Fuel Line Leakage
6.1.5.1. The power system of the test vehicle (e.g. fuel cell stack or engine) is warmed up and
operating at its normal operating temperature with the operating pressure applied to
fuel lines.
6.1.5.2. Hydrogen leakage is evaluated at accessible sections of the fuel lines from the
high-pressure section to the fuel cell stack (or the engine), using a gas leak detector or
a leak detecting liquid, such as soap solution.
6.1.5.3. Hydrogen leak detection is performed primarily at joints.
6.1.5.4. When a gas leak detector is used, detection is performed by operating the leak detector
for at least 10s at locations as close to fuel lines as possible.
6.1.5.5. When a leak detecting liquid is used, hydrogen gas leak detection is performed
immediately after applying the liquid. In addition, visual checks are performed a few
minutes after the application of liquid in order to check for bubbles caused by trace
leaks.
6.1.6. Installation Verification
The system is visually inspected for compliance.
6.2. Test Procedures for Compressed Hydrogen Storage System
6.2.1. Test procedures for qualification requirements of CHSS are organised as follows:
Paragraph 6.2.2 and 6.2.3 contain the test procedures for baseline performance
metrics (requirement of Paragraph 5.1.1.) and performance durability (requirement of
Paragraph 5.1.2.)
Paragraph 6.2.4 contains the test procedures for expected on-road performance
(requirement of Paragraph 5.1.3.)
Paragraph 6.2.5 contains the test procedures for service terminating performance in
Fire (requirement of Paragraph 5.1.4.)
Paragraph 6.2.6 contains the test procedures for performance durability of primary
closures (requirement of Paragraph 5.1.5.)
Unless otherwise specified, the ambient temperature for all tests shall be 20 ± 15°C.
Unless otherwise specified data sampling for pressure cycling shall be at least 1Hz.
Unless otherwise specified, the acceptable tolerances of the open ended test
parameters may be recommended by the manufacturer. In lieu of accepting
manufacturer guidance, suggested tolerances are provided in Section O.

6.2.3. Test Procedures for Performance Durability (Requirement of Paragraph 5.1.2.)
6.2.3.1. Proof Pressure Test
The container with its container attachments (if applicable), as specified, is pressurised
smoothly and continually with a hydraulic fluid or gas until the target test pressure level
is reached and then held for the duration specified in Table 4.
Table 4
Target Pressure and Holding Duration of Proof Pressure Test
Purpose Target Pressure Holding Duration
(Initial) proof pressure test
(Paragraph 5.1.2.1. and 5.1.3.1.)
Residual proof pressure test
(Paragraph 5.1.2.7. and 5.1.3.4.)
≥150% NWP ≥30s
≥180% NWP ≥4min
6.2.3.2. Drop (Impact) Test (Unpressurised)
The container and its container attachments (if any) is drop tested without internal
pressurisation or attached valves. The surface onto which the test article is dropped
shall be a smooth, horizontal concrete pad or other flooring type with equivalent
hardness. No attempt shall be made to prevent the test article from bouncing or falling
over during a drop test, but the test article shall be prevented from falling over during
the vertical drop test.
The test article shall be dropped in any one of the following four orientations:
(a)
(b)
(c)
From a horizontal position with the bottom 1.8m above the surface onto which it
is dropped. In case of non-axisymmetric container, the largest projection area of
the container shall be oriented downward and aligned horizontally, the shut-off
valve interface location and its centre of gravity should be horizontally aligned as
it is feasible;
From a vertical position with the shut-off valve interface location upward with a
drop height calculated based on a potential energy of 488J. In no case shall the
height of the lower end be less than 0.1m or greater than 1.8m. In case of
non-axisymmetric container, the shut-off valve interface location and its centre
of gravity shall be vertically aligned;
From a vertical position with the shut-off valve interface location downward, with
a drop height calculated based on a potential energy of 488J. In no case shall
the height of the lower end be less than 0.1m or greater than 1.8m. If the
container is symmetrical (identical ends), this drop orientation is not required. In
case of non-axisymmetric container, the shut-off valve interface location and its
centre of gravity shall be vertically aligned;

6.2.3.3. Surface Damage Test (Unpressurised)
The surface damage tests and the chemical exposure tests (Paragraph 6.2.3.4.) shall
be conducted on the surface of the pressure bearing chamber of the container as long
as it is accessible regardless of the existence of the container attachments.
If the container attachments can be removed in accordance with the process specified
by the manufacturer, then the container attachments shall be removed, and the tests
shall be conducted on the surface of the pressure bearing chamber of the container.
Otherwise, the tests shall be conducted on the surface of the container attachments as
indicated in Figure 4.
Figure 4
Surface Damage Flow Chart
The test proceeds in the following sequence:
(a)
Surface flaw generation: A saw cut at least 0.75mm deep and 200mm long is
made on the surface specified above.
If the container is to be affixed to the vehicle by compressing its composite
surface, then a second cut at least 1.25mm deep and 25mm long is applied at
the end of the container which is opposite to the location of the first cut;

6.2.3.4. Chemical Exposure and Ambient Temperature Pressure Cycling Test
Each of the 5 areas of the unpressurised container (with container attachments, if
applicable) preconditioned by pendulum impact (Paragraph 6.2.3.3.(b)) is exposed to
one of five solutions:
(a)
(b)
(c)
(d)
(e)
19% (by volume) sulphuric acid in water (battery acid);
25% (by weight) sodium hydroxide in water;
5% (by volume) methanol in gasoline (fluids in fuelling stations);
28% (by weight) ammonium nitrate in water (urea solution); and
50% (by volume) methyl alcohol in water (windshield washer fluid).
The test article is oriented with the fluid exposure areas on top. A pad of glass wool
approximately 0.5mm thick and 100mm in diameter is placed on each of the five
preconditioned areas. A sufficient amount of the test fluid is applied to the glass wool
to ensure that the pad is wetted across its surface and through its thickness for the
duration of the test. A plastic covering may be applied over the glass wool to prevent
evaporation.
The exposure of the test article with the glass wool is maintained for at least 48h with
the test article held at ≥125% NWP (applied hydraulically) and ambient temperature
before the test article is subjected to further testing.
The test article is pressure cycled from 2 ± 1MPa to the target pressures specified in
Table 5. The glass wool pads are removed and the container surface is rinsed with
water after the pressure cycling is completed.
Table 5
Pressure Cycles and Conditions – Chemical Exposure
and Ambient Temperature Pressure Cycling Test
Purpose Number of Cycles Target Pressure Temperature Rate
Chemical exposure 60% the specified number
and ambient of cycles determined in
temperature pressure Paragraph 5.1.1.2.
cycling test
(Paragraph 5.1.2.4.)
of which the last 10 cycles ≥150% NWP
≥125% NWP Environment:
20 ± 15°C
Hydraulic fluid:
20 ± 15°C
≤10 cycles
per minute

6.2.4. Test Procedures for Expected On-road Performance
No. of
cycles
Test sequence and parameters of the ambient and extreme temperature gas pressure
cycling test are specified in Tables 7a and 7b.
Table 7a
Ambient and Extreme Temperature Gas Pressure Cycling Test Parameters
Ambient
Conditions
Initial CHSS
Equilibration
Fuel Delivery
Temperature
Initial
Pressure
Target Pressure
5 ≤-25°C ≤-25°C 20 ± 5°C ≤2MPa ≥100% SOC
5 ≤-25°C ≤-25°C -33°C to -40°C ≤2MPa ≥100% SOC
15 ≤-25°C N/A -33°C to -40°C ≤2MPa ≥100% SOC
5 ≥50°C,
≥80% RH
20 ≥50°C,
≥80% RH
≥50°C,
≥80% RH
-33°C to -40°C ≤2MPa ≥100% SOC
N/A -33°C to -40°C ≤2MPa ≥100% SOC
200 20°C ± 5°C N/A -33°C to -40°C ≤2MPa ≥100% SOC
1st
permeation
25 ≥50°C,
≥80% RH
55°C to 60°C 55°C to 60°C N/A N/A ≥100% SOC
N/A -33°C to -40°C ≤2MPa ≥100% SOC
25 ≤-25°C N/A -33°C to -40°C ≤2MPa ≥100% SOC
200 20 ± 5°C N/A -33°C to -40°C ≤2MPa ≥100% SOC
2nd
permeation
55°C to 60°C 55°C to 60°C N/A N/A ≥100% SOC

(b)
(c)
(d)
(e)
The ramp rate for pressurisation shall be greater than or equal to the linearly
interpolated ramp rate in Table 7b according to the CHSS volume; however, if
the measured internal temperature in the CHSS container is greater than 85°C,
then the pressure ramp rate shall be decreased;
If devices and/or controls are used in the intended vehicle application to prevent
an extreme internal temperature of the CHSS container, the test may be
conducted with these devices and/or controls (or equivalent measures);
The de-fuelling rate shall be greater than or equal to the intended vehicle’s
maximum fuel-demand rate. Out of the 500 pressure cycles, any 50 pressure
cycles are performed using a de-fuelling rate greater than or equal to the
maintenance de-fuelling rate specified by the manufacturer on CHSS container
labelling or operating/maintenance manuals;
The maximum allowable leak rate from the CHSS from a single point is in
accordance with Paragraph 6.2.4.3(b).
6.2.4.2. Gas Permeation Test (Pneumatic)
This test is performed after each group of 250 pneumatic pressure cycles in accordance
with Paragraph 6.2.4. Table 7a.
The CHSS is fully filled with hydrogen gas to ≥100% SOC and soaked for a minimum
of 12h at 55°C to 60°C in a sealed chamber prior to the start of the test. The test shall
continue until the permeation rate reaches a steady state based on at least three
consecutive rates separated by at least 12h being within ±10% of the previous rate, or
500h, whichever occurs first.
6.2.4.3. Localised Gas Leak Test (Pneumatic)
A bubble test may be used to fulfil this requirement. The following procedure is used
when conducting the bubble test:
(a)
The exhaust of the shutoff valve (and other internal connections to hydrogen
systems) shall be capped for this test (as the test is focused on external leakage).
At the discretion of the manufacturer or test laboratory, the test article may be
immersed in the leak-test fluid or leak-test fluid applied to the test article when
resting in open air. Bubbles can vary greatly in size, depending on conditions.
The tester estimates the gas leakage based on the size and rate of bubble
formation.
(b)
For a localised rate of 0.005mg/s (3.6Nml/min), the resultant allowable rate of
bubble generation is about 2,030 bubbles per minute for a typical bubble size of
1.5mm in diameter. Even if much larger bubbles are formed, the leak shall be
readily detectable. For an unusually large bubble size of 6mm in diameter, the
allowable bubble rate would be approximately 32 bubbles per minute.

6.2.5.2. Test Conditions and Wind Shielding
Testing can be conducted either indoors or outdoors.
Ambient temperature and wind speed and direction shall be measured and recorded if
testing conducted outdoors.
Outdoor testing shall not be conducted when precipitation (i.e. rain, snow, sleet, etc.)
is occurring unless the test area with the test article and burner is protected such that
the precipitation does not adversely affect the test result.
Wind shielding such as are walls, fencing, and/or enclosures shall be used for the fire
tests at sites susceptible to wind effects during the tests (pre-test checkout and CHSS
fire test). The wind shielding shall provide at least 0.5 m separation between the CHSS
test article (or pre-test cylinder) and the wind shields such that the fire can freely draft
and that the length of jet flames (if any) from the CHSS test article can be confirmed.
Openings (or other provisions) shall be provided in wind shielding to allow fresh air to
enter the test area and for the combustion products to be exhausted. The adequacy of
wind shielding shall be verified by compliance to Table 10 during a pre-test check-out
prior to the CHSS fire test.
Note:
Rupture of container during the fire test is likely to result in blast waves and
the rapid expulsion of container materials and attachments as well as the
hydrogen contents.
6.2.5.3. Burner Definition
These effects can result in uncontrolled movement of the CHSS test article
and secondary explosions due to the build-up of high pressure, flammable
gas mixtures within the test area and wind shielding (if used).
Countermeasures to these effects need to be addressed and implemented
as part of locating the test site relative to other equipment and designing and
constructing wind shielding (if used) and test support structure to prevent
severe injury to personnel and unacceptable property damage.
In order to conduct the two-stage localized/engulfing fire test, the burner is divided into
two zones:
(a)
(b)
The localized burner zone operates by itself during the localized fire stage;
The engulfing burner extension simulates the spread of the fire from the localized
burner zone to the remainder of the burner. The engulfing burner zone is
comprised of both the localized burner zone and the engulfing fire extension.
6.2.5.3.1. Fuel Supply and Burner Control
The localized and engulfing burners shall be LPG-fired.
The LPG burner fuel flow to both the localized burner zone and engulfing burner
extension shall be measured to set burner fuel flows to the specific heat release rates
(HRR/As) defined in Paragraph 6.2.5.4.5.2.
The measured fuel flow(s) shall be recorded throughout the tests on a 1-second basis.

(c)
As illustrated in Figure 9 below, the nozzles on the third and fourth rails aim
toward the centre of the burner to form a "hot zone" in this targeted area. See
also Figures 14 and 15 in Part I.
Nozzle type
Table 8
Definition of Burner Nozzles for The Prescribed Burner
Item
– LPG orifice in nozzle 1.0 ± 0.1mm ID
Description
LPG fuel nozzle with air pre-mix
– Air ports in nozzle Four (4) holes, 6.4mm ± 0.6mm ID
– Fuel/Air mixing tube in nozzle 10 ± 1mm ID
Number of rails 6
Centre-to-centre spacing of rails
100 ± 10mm
Centre-to-centre nozzle spacing along the rails 50 ± 5mm
6.2.5.3.2.2. The values for L , L , and W defined above shall be used for calculating HRR/As
for the localized burner zone and engulfing burner extension.
The borders of the localized burner zone and the engulfing burner extension shall be
defined using L , L , and W so that test articles can be properly located and
oriented for CHSS fire test. The borderline between the localized burner zone and the
engulfing burner extension is located mid-way between the nozzles of the two zones
and used as a datum for locating the outside borders at distances L and L away
from the datum towards the localized burner zone and the engulfing burner extension,
respectively. The centres of the outside rails of the burner zone(s) define the remaining
two borders.
Note:
Figure 17 in Part 1 shows an illustration of borderlines.
6.2.5.4. Pre-test Checkout of Burner
The purpose of the pre-test checkout is to verify that the localized and engulfing burner
zones are operating as expected and that the test setup including wind shields are
functional and capable of delivering repeatable results prior to conducting the CHSS
fire tests.
6.2.5.4.1. Pre-test Checkout Frequency
This pre-test shall be performed at least once prior to conducting CHSS fire tests. If the
burner and test setup is modified then the pre-test checkout shall be repeated before
the CHSS fire test.

(a)
(b)
(c)
TBR, TBC and TBL are temperature measurements on the bottom surface of the
pre-test cylinder that are directly exposed to the burner flame;
TMRF, TMCF, TMLF, TMRR, TMCR and TMLR are temperature measurements
on the surface of the pre-test cylinder at mid-height. These temperatures are
used for data collection only during the pre-test verification and calibration of the
localized and engulfing fires;
TUR, TUC and TUL are temperature measurements on the top surface of the
pre-test cylinder that are opposite the side directly exposed to the burner flame.
Additional thermocouples may be located at TPRD sensing points or any other
locations for optional diagnostic purposes.
6.2.5.4.3.2. Thermocouples shall also be located 25 ± 5mm below the pre-test cylinder along the
length of the cylinder for the purpose of developing reference temperature levels during
the pre-test checkout that can be subsequently used for monitoring the burner during
the CHSS fire test. Three (3) thermocouples (TBR25, TBC25 and TBL25) shall
correspond to pre-test cylinder instrumentation as shown in Figure 7. Thermocouples
used to back up or supplement TBR25, TBC25 and TBL25 may also be added along
the centre line of the burner. See Paragraph 6.2.5.6. for requirements for positioning
thermocouples for burner monitoring during the CHSS fire test.
The thermocouples used for burner monitoring shall be unshielded (i.e. unprotected by
metal wells) ɸ3.2mm (or less) K-type sheath thermocouples. Given the need to
maintain the distance from the steel container within ±5mm, these thermocouples shall
be mechanically supported to prevent movement or drooping. If testing of CHSSs with
large width/diameters is contemplated, then mounting shall maintain the distance
between the CHSS and the burner monitors as the spacing between the burner and
CHSS is adjusted in Paragraph 6.2.5.4.5.5.
6.2.5.4.3.3. Thermocouple readings shall be recorded at least once a second and then used to
calculate the following parameters:
(a) TB is the bottom surface temperature of the pre-test cylinder based on TBR;
(b) TMF are the surface temperatures of the front side of the pre-test cylinder
based on TMRF;
(c) TMR is the surface temperatures of the rear side of pre-test cylinder based
on TMRR;
(d) TU is the top surface temperature of the pre-test cylinder based on TUR;
(e) TB is the burner monitor below the pre-test cylinder (and subsequently
below the CHSS test article in Paragraph 6.2.5.6.) based on TBR25.
Thermocouples used to back up or supplement TBR25 may also be included in
the calculation of the average temperature of the burner monitors in the localized
fire zone. Any thermocouple measurement that has been compromised or failed
(or is not located within the localized fire zone) shall be disregarded from the
calculation of average temperature of the burner monitor;

Figure 9
End View of Mounting of the Pre-test Cylinder Relative to the Burner
6.2.5.4.5. Pre-test Checkout Process
6.2.5.4.5.1. Prior to pre-test checkout of the burner, wind shieldings shall be installed in accordance
with Paragraph 6.2.5.2.
6.2.5.4.5.2. The burner shall, at a minimum, be operated at fuel flow setpoints that match the
settings intended for the localized and engulfing burners during the CHSS fire test.
Suggested settings for the burners are provided in Table 9; however, any setting within
the allowable ranges of HRR/A in Table 9 may be selected.
Note:
During the engulfing fire stage, both the localized burner and the engulfing
burner extension need to be set to the intended HRR/A for uniform heat
release from the engulfing burner.
Fire Stage
Table 9
Allowable Range of Operation and the
Suggested Settings for the Prescribed Burner
Allowable Range of Specific
Heat Release Rate (HRR/A)
Localized Burner 200 – 500kW/m 300kW/m
Engulfing Burner 400 – 1000kW/m 700kW/m
Suggested Setting of Specific
Heat Release Rate (HRR/A)
6.2.5.4.5.3. The 60-second rolling averages of individual temperature readings in the localized fire
zone (i.e. TB , TMF , TMR and TU ) and the engulfing fire zone (i.e. TBR,
TBC, TBL, TMRF, TMCF, TML, TMRR, TMCR, TMLR, TUR, TUC and TUL) shall be in
accordance with Table 10 at the HRR/A settings selected for the CHSS fire test in
Paragraph 6.2.5.7.

6.2.5.4.5.5. If results are not satisfactory, then the source of the variation in burner performance
shall be identified and corrected and then re-tested until the requirements for pre-test
verification are met. Adjustment of the height is permissible to achieve acceptable
operation within the allowable operating ranges as defined in Tables 9 and 10.
When the width/diameter of the CHSS test article is larger than the width of the burner
and the shape of the bottom of the CHSS test article (for example, a flat horizontal
plane as illustrated for CHSS in Figures 30 and 33 in Part I) impedes the burner exhaust
from readily flowing up and around the CHSS test article during the CHSS fire test, then
the burner air flow can be restricted and the burner monitors may not be able to achieve
the required minimum temperatures during the localized and/or engulfing fire stages of
the CHSS fire test. If the CHSS test article is expected to impede the burner flow (or if
the burner monitors did not achieve the required temperatures during the CHSS fire
test), then the following additional pre-test is required to determine the appropriate
height for mounting the CHSS test article above the burner such that required
temperatures are achieved:
(a)
(b)
(c)
(d)
Note:
A pre-test plate (made of steel) with approximately the length and width/diameter
of the CHSS test article is mounted above the burner to simulate the bottom on
the CHSS test article at an initial height of 100mm.
Burner monitors as defined in Paragraph 6.2.5.4.3.2. are located 25 ± 5mm
below the surface.
The burners are operated in the localized and engulfing modes (at the HRR/As
established above) and the temperatures of the burner monitors are measured.
If the burner monitors for both the localized and engulfing fire stages do not meet
the minimum criteria (defined in Paragraph 6.2.5.4.5.4.), then the height of the
pre-test plate above the burner shall be increased by 50mm and the process in
Steps (b) and (c) are repeated until a satisfactory height is achieved.
Satisfactory results are expected at heights of 200 – 250mm.
If the burner monitors meet the minimum criteria (defined above) for both the localized
and engulfing fire stages, then the required height for locating the CHSS test article
above the burner has been determined and the pre-test is complete.
6.2.5.5. Mounting of the CHSS Test Article above the Burner
After the pre-test checkout(s) have been satisfactorily completed, the CHSS test article
shall be mounted above the burner.

6.2.5.5.2. Targeting of the Localized and Engulfing Burner Zones on the CHSS
Localized fire shall be targeted on the CHSS test article to challenge the ability of the
TPRDs to sense the fire and respond in order to protect the container. This requirement
is met as follows:
(a)
For CHSS where the manufacturer has not opted to include vehicle-specific
features (as defined in Paragraph 6.2.5.1.), the CHSS test article shall be rotated
relative to the localized burner to minimize the ability to TPRDs to sense the fire
and respond. Shields, panels, wraps, structural elements and other features
added to the container shall be considered when establishing the worst case
orientation relative to the localized fire as parts and features intended to protect
sections of the container but can (inadvertently) leave other potions or
joints/seams vulnerable to attack and/or hinder the ability of TPRDs to respond.
For CHSS where the manufacturer has opted to include vehicle-specific features
(as defined in Paragraph 6.2.5.1.), the CHSS test article is oriented relative to
the localized burner to provide the worst case fire exposure identified for the
specific vehicle.
(b)
The localized burner shall be located under the CHSS test article such that the
distance from localized fire zone to the nearest TPRD sense point(s) is
maximized.
The engulfing fire zone shall extend in one direction from the localized fire zone toward
the nearest TPRD (or sense point). The engulfing burner can extend beyond the
TPRD(s) if the distance from the localized burner is less than the maximum allowable
extension of the engulfing burner as defined above (i.e. 1,400 ± 50mm).
Note:
Examples of commonly-encountered situations for targeting the localized fire
zone on the CHSS test article and positioning the engulfing fire zone under
the CHSS test article are provided in the rationale (in Part I Section E
Figures 28 to 35).
6.2.5.6. Instrumentation and Connections to the CHSS Test Article
6.2.5.6.1. The definition and mounting of the thermocouples for burner monitoring are analogous
to Paragraph 6.2.5.4.3.2. for the pre-test checkout. See Figures 10 and 11 for examples
of the mounting below cylindrical and conformable containers, respectively.
At least one thermocouple for burner monitoring shall be located in the localized fire
exposure of the CHSS test article, and two thermocouples shall be located in the
extension of the engulfing fire exposure on the CHSS test article. Additional
thermocouples may be added to back up or supplement burner monitoring along the
centre line of the localized and engulfing burners.

6.2.5.7.3. After 10min from start of test, the second stage is initiated by starting fuel flow to the
engulfing burner extension and igniting the burner:
(a)
(b)
After ignition is confirmed, the fuel flowrates to both the localized and engulfing
fire extension are set to the value that matches the desired specific heat release
(HRR/A) for the engulfing burner stage in Paragraph 6.2.5.4.5.3.
Within 2min of the start of ignition of the engulfing burner (i.e. within 12min from
start of test), the 60-second rolling average of the engulfing burner monitor
(TB ) shall be equal or greater than Tmin as determined in
Paragraph 6.2.5.4.5.4.
Notes:
(i)
Monitoring of the 60-second rolling average of the engulfing burner
monitor (TB ) is not required after the above criteria are met as the
burner monitor readings may be compromised by expansion or falling of
materials from the CHSS test article during subsequent CHSS fire test.
(ii) If the test is terminated because TB did not achieve required
temperature within the required time, requirements in Paragraph 6.2.5.2.
for providing wind shielding and Paragraph 6.2.5.4.5. for adjusting the
burner operation and setup should be considered prior to re-test.
6.2.5.7.4. Minor movement of the CHSS test article and subsequent repositioning of the CHSS
test article relative to the burners is allowed when TPRD(s) activate.
The fire test continues until either:
(a)
(b)
the CHSS vents and the pressure falls to less than 1MPa; or
a total test of 1h from start of test is reached for CHSS in LDV or 2h for CHSS in
HDV.
When the test is completed, the burner fuel flow shall be shut off within 1min, and the
CHSS shall be depressurized (if not already near ambient pressure) and then purged
with inert gas for safe post-test handling.
Note:
Suggestions are provided in Part I, Section E(d) for technical data and
information to be provided with CHSS fire test report.

6.2.6.1.2. Accelerated Life Test.
Eight TPRD units undergo testing; three at the manufacturer's specified activation
temperature, T , and five at an accelerated life temperature. The Accelerated Life test
temperature is T , given in °C by the expression:
Where β = 273.15, T is 85°C, and T is the manufacturer's specified activation
temperature. The TPRD is placed in an oven or liquid bath with the temperature held
constant (±1°C). The pressure on the TPRD inlet is 125% NWP. The pressure supply
may be located outside the controlled temperature oven or bath. Each device is
pressurised individually or through a manifold system. If a manifold system is used,
each pressure connection may include a check valve to prevent pressure depletion of
the system when one specimen fails. The three TPRDs tested at T shall activate in
less than 10h. The five TPRDs tested at T shall not activate in less than 500h and shall
meet the requirements of Paragraph 6.2.6.1.8. (Leak Test).
6.2.6.1.3. Temperature Cycling Test
(a)
(b)
(c)
(d)
An unpressurised TPRD is placed in a liquid bath maintained at ≤-40°C for at
least 2h. The TPRD is transferred to a liquid bath maintained at ≥85°C within
5min, and maintained at that temperature at least 2h. The TPRD is transferred
to a liquid bath maintained at ≤-40°C within 5min;
Step (a) is repeated until 15 thermal cycles have been achieved;
With the TPRD conditioned for at least 2h in the ≤-40°C liquid bath, the TPRD is
pressure cycled between ≤2MPa and ≥80% NWP for 100 cycles while the liquid
bath is maintained at ≤-40°C;
Following the thermal and pressure cycling, the pressure relief device shall
comply with the requirements of the Leak Test (Paragraph 6.2.6.1.8.), except
that the Leak Test shall be conducted at ≤-40°C. After the Leak Test, the TPRD
shall comply with the requirements of the Bench Top Activation Test
(Paragraph 6.2.6.1.9.) and then the Flow Rate Test (Paragraph 6.2.6.1.10.).

(f)
(g)
The force/impingement from this salt application shall not remove corrosion or
damage the coatings/paints system of test samples;
The complex salt solution in per cent by mass shall be as specified below:
(i) Sodium Chloride (NaCl): 0.9%;
(ii) Calcium Chloride (CaCl ): 0.1%;
(iii) Sodium Bicarbonate (NaHCO ): 0.075%.
Sodium Chloride must be reagent grade or food grade. Calcium Chloride must
be reagent grade. Sodium Bicarbonate must be reagent grade or food grade
(e.g. Baking Soda or a comparable product is acceptable). Water must meet
ASTM D1193-06(2018) Type IV requirements.
Note:
Either CaCl or NaHCO material must be dissolved separately in water
and added to the solution of the other materials. If all solid materials
are added dry, an insoluble precipitate may result;
(h)
(i)
(j)
(k)
(l)
TPRDs shall be installed in accordance with the manufacturer’s recommended
procedure and exposed to the cyclic corrosion test method described in
Table 12;
Repeat the cycle daily until 100 cycles of exposure have been completed. For
each salt mist application, the solution shall be sprayed as an atomised mist,
using the spray apparatus to mist the components until all areas are thoroughly
wet / dripping. Suitable application techniques include using a plastic bottle, or a
siphon spray powered by oil-free regulated air to spray the test samples. The
quantity of spray applied shall be sufficient to visibly rinse away salt accumulation
left from previous sprays. A total of four salt mist applications shall be applied
during the ambient stage. Salt mist is not applied during any other stage of the
test. The first salt mist application occurs at the beginning of the ambient stage.
Each subsequent salt mist application shall be applied approximately 90min after
the previous application in order to allow adequate time for test sample to dry. If
the test must be interrupted for weekends and holidays, the test article shall be
kept at the ambient temperature of 25 ± 3°C ˚and the relative humidity of 45 ±
10% and the cycle shall restart from ambient stage;
Humidity ramp times between the ambient and wet condition, and between the
wet and dry conditions, can have a significant effect on test acceleration (this is
because corrosion rates are highest during these transition periods). The time
from ambient to the wet condition shall be 60 ± 5min and the transition time
between wet and dry conditions shall be 180 ± 10min;
Immediately after the corrosion test, the samples are rinsed with fresh tap water
and allowed to dry before evaluating;
The TPRDs shall then comply with the requirements of the leak test
(Paragraph 6.2.6.1.8.), bench top activation test (Paragraph 6.2.6.1.9.) and flow
rate test (Paragraph 6.2.6.1.10.).

6.2.6.1.7. Drop and Vibration Test
(a)
TPRD units representative of their final assembled form are dropped from a
height of ≥2m without restricting its motion as a result of gravity, at ambient
temperature onto a smooth concrete surface. The TPRD is allowed to bounce
on the concrete surface after the initial impact.
Up to six separate units may be used such that all six of the major axes are
covered (i.e. one direction drop per sample, covering the opposing directions of
three orthogonal axes: vertical, lateral and longitudinal). Compliance testing can
be performed in any of these six orientations. At the manufacturer’s discretion,
one unit may be dropped in all six orientations.
After each drop, the sample shall be examined for visible damage. Any of the six
dropped orientations that do not have exterior damage that indicates that the
part is unsuitable for use (i.e. threads damaged sufficiently that part is rendered
unusable), shall proceed to step (b).
Note: any samples with damage from the drop that results in the TPRD not being
able to be installed (i.e. thread damage) shall not proceed to step (b) and shall
not be considered a failure of this test;
(b)
Each of the TPRD units dropped in step (a) that did not have visible damage and
one additional unit not subjected to a drop are mounted in a test fixture in
accordance with manufacturer's installation instructions and vibrated 30min
along each of the three orthogonal axes (vertical, lateral and longitudinal) at the
most severe resonant frequency for each axis.
The most severe resonant frequencies are determined using an acceleration of
1.5g and sweeping through a sinusoidal frequency range of 10 to 500Hz in
10min. The resonance frequency is identified by a pronounced increase in
vibration amplitude. If the resonance frequency is not found in this range, the test
shall be conducted at 40Hz.
Following this test, each sample shall subsequently comply with the
requirements of the Leak Test (Paragraph 6.2.6.1.8.), Bench Top Activation Test
(Paragraph 6.2.6.1.9.) and Flow Rate Test (Paragraph 6.2.6.1.10.).

6.2.6.1.10. Flow Rate Test
(a)
(b)
(c)
(d)
Eight TPRD units are tested for flow capacity. The eight units consist of three
new TPRD units and one TPRD unit from each of the following tests:
Paragraphs 6.2.6.1.1., 6.2.6.1.3., 6.2.6.1.4., 6.2.6.1.5. and 6.2.6.1.7.;
Each TPRD unit is activated according to Paragraph 6.2.6.1.9. After activation
and without cleaning, removal of parts, or reconditioning, each TPRD unit is
subjected to a flow test;
Flow rate testing is conducted with an inlet pressure of 2 ±0.5MPa. The outlet is
at ambient pressure. The inlet pressure and flow rate are recorded;
Flow rate is measured with accuracy within ±2%. The lowest measured value of
the eight pressure relief devices shall not be less than 90% of the highest flow
value.
6.2.6.1.11. Atmospheric Exposure Test
The atmospheric exposure test applies to qualification of TPRDs if the component has
non-metallic materials exposed to the atmosphere during normal operating conditions.
(a)
(b)
All non-metallic materials that provide a fuel containing seal, and that are
exposed to the atmosphere, for which a satisfactory declaration of properties is
not submitted by the applicant, shall not crack or show visible evidence of
deterioration after exposure to oxygen for at least 96h at 70°C and 2MPa in
accordance with ISO 188:2011 or ASTM D572-04(2019);
All elastomers that are exposed to the atmosphere shall demonstrate resistance
to ozone by one or more of the following:
(i)
(ii)
Specification of elastomer compounds with established resistance to
ozone;
Component testing in accordance with ISO 1431-1:2012, ASTM D1149-18,
or equivalent test methods;
(iii) The test piece shall be stressed to 20% elongation, exposed to air at 40°C
with an ozone concentration of 50 parts per hundred million for 120h. The
non-metallic materials in the test piece shall not crack or show visible
evidence of deterioration after exposure to ozone.

6.2.6.2.3. Extreme Temperature Pressure Cycling Test
The total number of operational cycles is 15,000 for the check valve and 50,000 for the
shut-off valve. The valve unit is installed in a test fixture corresponding to the
manufacturer's specifications for installation.
(a)
The operation of the unit is continuously repeated using hydrogen or
non-reactive gas at all specified temperatures and pressures as follows:
(i)
(ii)
(iii)
Ambient temperature cycling. The unit undergoes 90% of the total
operational cycles at ≥100% NWP with the part stabilised at ambient
temperature;
High temperature cycling. The unit then undergoes 5% of the total
operational cycles at ≥125% NWP with the part stabilised at ≥85°C;
Low temperature cycling. The unit then undergoes 5% of the total
operational cycles at ≥80% NWP with the part stabilised at ≤-40°C.
(b)
The operational cycle requirements shall be as follows:
(i) Check Valve: A check valve shall be capable of withstanding 15,000
cycles of operation, and at least 24h of chatter flow when submitted to the
following test procedure.
The check valve shall be connected to a test fixture. The required test
pressure is applied in six pulses to the inlet of the check valve with the
outlet closed. The pressure shall then be vented from the check valve inlet.
Failure of the check valve to reseat and prevent backflow shall constitute
failure of the check valve. The pressure shall then be lowered on the check
valve outlet side to ≤60% of NWP prior to the next cycle.
Following the operation cycles, the check valve shall be subjected to at
least 24h of chatter flow at a flow rate that causes the most chatter (valve
flutter).
At the completion of the test, the check valve shall comply with the leak
test (Paragraph 6.2.6.2.2.) and hydrostatic strength test
(Paragraph 6.2.6.2.1.).

(b)
The apparatus used for this test shall consist of a fog/environmental chamber,
suitable water supply conforming to ASTM D1193-06(2018) Type IV, provisions
for heating the chamber, and the necessary means of controlling temperature
between 22°C and 62°C. The apparatus shall include provisions for a supply of
suitably conditioned compressed air and one or more nozzles for fog generation.
The nozzle or nozzles used for the generation of the fog shall be directed or
baffled to minimise any direct impingement on the test samples.
(c) The apparatus shall consist of the chamber design as defined in ISO 6270-
2:2017. During "wet-bottom" generated humidity cycles, the testing agency must
confirm that visible water droplets are found on the samples to verify proper
wetness.
(d)
(e)
(f)
(g)
Steam generated humidity may be used provided the source of water used in
generating the steam is free of corrosion inhibitors. During steam generated
humidity cycles, the proper wetness shall be confirmed by visual inspection of
visible water droplets on the samples.
The apparatus for the dry off stage shall have the ability to obtain and maintain
the following environmental conditions: temperature: 60 ± 2°C and humidity:
≤30% RH. The apparatus shall also have sufficient air circulation to prevent
temperature stratification, and also allow thorough drying of the test samples.
The force/impingement from this salt application shall not remove corrosion or
damage the coatings/paints system of test samples.
The complex salt solution in per cent by mass shall be as specified below:
(i) Sodium Chloride (NaCl): 0.9%;
(ii) Calcium Chloride (CaCl ): 0.1%;
(iii) Sodium Bicarbonate (NaHCO ): 0.075%.
Sodium Chloride must be reagent grade or food grade. Calcium Chloride must
be reagent grade. Sodium Bicarbonate must be reagent or food grade (e.g.
Baking Soda or comparable product is acceptable). Water must meet ASTM
D1193-06(2018) Type IV requirements.
Note:
Either CaCl or NaHCO material must be dissolved separately in water
and added to the solution of the other materials. If all solid materials
are added dry, an insoluble precipitate may result.
(h)
The component samples shall be installed in accordance with the manufacturer’s
recommended procedure and exposed to the cyclic corrosion test method
described in Table 13.

6.2.6.2.6. Atmospheric Exposure Test
The atmospheric exposure test applies to qualification of check valve and shut-off
valves if the component has non-metallic materials exposed to the atmosphere during
normal operating conditions.
(a)
(b)
All non-metallic materials that provide a fuel containing seal, and that are
exposed to the atmosphere, for which a satisfactory declaration of properties is
not submitted by the applicant, shall not crack or show visible evidence of
deterioration after exposure to oxygen for at least 96h at 70°C and 2MPa in
accordance with ISO 188:2011 or ASTM D572-04 (2019);
All elastomers shall demonstrate resistance to ozone by one or more of the
following:
(i)
(ii)
Specification of elastomer compounds with established resistance to
ozone;
Component testing in accordance with ISO 1431-1:2012, ASTM D1149-18,
or equivalent test methods;
6.2.6.2.7. Electrical Tests
(iii) The test piece, shall be stressed to 20% elongation, exposed to air at 40°C
with an ozone concentration of 50 parts per hundred million during 120h.
The non-metallic materials in the test piece shall not crack or show visible
evidence of deterioration after exposure to ozone.
The electrical tests apply to qualification of the shut-off valve; they do not apply to
qualification of check valves.
(a)
Abnormal voltage test. The solenoid valve is connected to a variable DC voltage
source. The solenoid valve is operated as follows:
(i)
(ii)
(iii)
An equilibrium (steady state temperature) hold is established for at least
1h at ≥1.5 times the rated voltage;
The voltage is increased to ≥two times the rated voltage or 60V, whichever
is less, and held for at least 1min;
Any failure shall not result in external valve leakage in accordance with
Paragraph 6.2.6.2.2., open valve or other unsafe conditions such as
smoke, fire or melting.
(b)
Insulation resistance test. 1,000V D.C. is applied between the power conductor
and the component casing for at least 2s. The minimum allowable resistance for
that component is 240kΩ.

7. VEHICLES WITH A LIQUEFIED HYDROGEN STORAGE SYSTEM (LHSSs)
7.1. LHSS Optional Requirements
As described in Paragraphs 23. and 118. of the preamble, individual Contracting
Parties may elect to adopt the UN GTR with or without the LHSS requirements in
Paragraph 7.
Paragraph 7. is organised as follows:
Paragraph 7.2. LHSS design qualification requirements
Paragraph 7.3. LHSS fuel system integrity
Paragraph 7.4. Test procedures for LHSS design qualification
Paragraph 7.5. Test procedures for LHSS fuel system integrity
7.2. LHSS Design Qualification Requirements
This Section specifies the requirements for the integrity of a liquefied hydrogen storage
system.
The hydrogen storage system qualifies for the performance test requirements specified
in this Section. All liquefied hydrogen storage systems produced for on-road vehicle
service shall be capable of satisfying requirements of Paragraph 7.2.
The manufacturer shall specify a maximum allowable working pressure (MAWP) for the
inner container.
The test elements within these performance requirements are summarised in
Table 12.
These criteria apply to qualification of storage systems for use in new vehicle
production. They do not apply to re-qualification of any single produced system for use
beyond its expected useful service or re-qualification after a potentially significant
damaging event.

7.2.1.3. Baseline Pressure Cycle Life
When using metallic containers and/or metallic vacuum jackets, the manufacturer shall
either provide a calculation in order to demonstrate that the container is designed
according to current regional legislation or accepted standards (e.g. in US the ASME
Boiler and Pressure Vessel Code, in Europe EN 1251-1 and EN 1251-2 and in all other
countries an applicable regulation for the design of metallic pressure containers), or
define and perform suitable tests (including Paragraph 7.4.1.3.) that prove the same
level of safety compared to a design supported by calculation according to accepted
standards.
For non-metallic containers and/or vacuum jackets, in addition to Paragraph 7.4.1.3.
testing, suitable tests shall be designed by the manufacturer to prove the same level of
safety compared to a metallic container.
7.2.2. Verification for Expected On-road Performance
7.2.2.1. Boil-off
7.2.2.2. Leak
The boil-off test is performed on a liquefied hydrogen storage system equipped with all
components as described in Paragraph G.1.(b). of the preamble (Figure 36 in
Section G of Part I). The test is performed on a system filled with liquid hydrogen per
the test procedure in Paragraph 7.4.2.1. and shall demonstrate that the boil-off system
limits the pressure in the inner storage container to below the maximum allowable
working pressure.
After the boil-off test in Paragraph 7.2.2.1., the system is kept at boil-off pressure and
the total discharge rate due to leakage shall be measured per the test procedure in
Paragraph 7.4.2.2. The maximum allowable discharge from the hydrogen storage
system is R × 150Nml/min where R = (Vwidth+1) × (Vheight+0.5) × (Vlength+1)/30.4
and Vwidth, Vheight, Vlength are the vehicle width, height, length (m), respectively.
7.2.2.3. Vacuum Loss
The vacuum loss test is performed on a liquefied hydrogen storage system equipped
with all components as described in Paragraph G.1.(b). and Figure 36 in Part I. The
test is performed on a system filled with liquid hydrogen per the test procedure in
Paragraph 7.4.2.3. and shall demonstrate that both primary and secondary pressure
relief devices limit the pressure to the values specified in Paragraph 7.4.2.3. in case
vacuum pressure is lost.

(e)
(f)
(g)
(h)
Resistance to dry-heat test (Paragraph 7.4.4.6. test procedure);
Ozone ageing test (Paragraph 7.4.4.7. test procedure);
Temperature cycle test (Paragraph 7.4.4.8. test procedure);
Flex line cycle test (Paragraph 7.4.4.9. test procedure).
7.2.5. Labelling
A label shall be permanently affixed on each container with at least the following
information: Name of the Manufacturer, Serial Number, Date of Manufacture, MAWP,
Type of Fuel. Any label affixed to the container in compliance with this section shall
remain in place. Contracting parties may specify additional labelling requirements.
7.3. LHSS Fuel System Integrity
This section specifies requirements for the integrity of the hydrogen fuel delivery
system, which includes the liquefied hydrogen storage system, piping, joints, and
components in which hydrogen is present. These requirements are in addition to
requirements specified in Paragraph 5.2., all of which apply to vehicles with liquefied
hydrogen storage systems with the exception of Paragraph 5.2.1.1. The fuelling
receptacle label shall designate liquid hydrogen as the fuel type. Test procedures are
given in Paragraph 7.5.
7.3.1. Flammable materials used in the vehicle shall be protected from liquefied air that may
condense on elements of the fuel system.
7.3.2. The insulation of the components shall prevent liquefaction of the air in contact with the
outer surfaces, unless a system is provided for collecting and vaporizing the liquefied
air. The materials of the components nearby shall be compatible with an atmosphere
enriched with oxygen.

7.4.1.2. Baseline Initial Burst Pressure
The test is conducted according to the following procedure:
(a)
(b)
(c)
(d)
(e)
The test is conducted on the inner container at ambient temperature;
The test is conducted hydraulically with water or a water/glycol mixture;
The pressure is increased at a constant rate, not exceeding 0.5MPa/min until
burst or leakage of the container occurs;
When MAWP is reached there is a wait period of at least 10min at constant
pressure, during which time the deformation of the container can be checked;
The pressure is recorded or written during the entire test.
For steel inner containers, the test is passed successfully if at least one of the two
passing criteria described in Paragraph 7.2.1.2. is fulfilled. For inner containers made
out of an aluminium alloy or other material, a passing criterion shall be defined which
guarantees at least the same level of safety compared to steel inner containers.
7.4.1.3. Baseline Pressure Cycle Life
Containers and/or vacuum jackets are pressure cycled with a number of cycles at least
three times the number of possible full pressure cycles (from the lowest to highest
operating pressure) for an expected on-road performance. The number of pressure
cycles is defined by the manufacturer under consideration of operating pressure range,
size of the storage and, respectively, maximum number of refuellings and maximum
number of pressure cycles under extreme usage and storage conditions. Pressure
cycling is conducted between atmospheric pressure and MAWP at liquid nitrogen
temperatures, e.g. by filling the container with liquid nitrogen to certain level and
alternately pressurising and depressurising it with (pre-cooled) gaseous nitrogen or
helium.

The pressure of the inner container and the vacuum jacket is recorded or written during
the entire test. The opening pressure of the first safety device is recorded or written.
The first part of test is passed if the following requirements are fulfilled:
(a)
(b)
(c)
The first pressure relief device opens below or at MAWP and limit the pressure
to not more than 110% of the MAWP;
The first pressure relief device does not open at pressure above MAWP;
The secondary pressure relief device does not open during the entire test.
After passing the first part, the test shall be repeated subsequently to regeneration of
the vacuum and cool-down of the container as described above.
(a)
(b)
(c)
(d)
(e)
The vacuum is re-generated to a value specified by the manufacturer. The
vacuum shall be maintained at least 24h. The vacuum pump may stay connected
until the time directly before the start of the vacuum loss;
The second part of the vacuum loss test is conducted with a completely
cooled-down container (according to the procedure in Paragraph 7.4.2.1.);
The container is filled to the specified maximum filling level;
The line downstream the first pressure relief device is blocked and the vacuum
enclosure is flooded with air at an even rate to atmospheric pressure;
The test is terminated when the second pressure relief device does not open any
more.
The pressure of the inner container and the vacuum jacket is recorded or written during
the entire test. For steel containers the second part of the test is passed if the secondary
pressure relief device does not open below 110% of the set pressure of the first
pressure relief device and limits the pressure in the container to a maximum 136% of
the MAWP if a safety valve is used, or, 150% of the MAWP if a burst disk is used as
the secondary pressure relief device. For other container materials, an equivalent level
of safety shall be demonstrated.
7.4.3. Verification Test for Service-terminating Performance Due to Fire
The tested liquefied hydrogen storage system shall be representative of the design and
the manufacturing of the type to be homologated. Its manufacturing shall be completely
finished and it shall be mounted with all its equipment.
The first part of the test is conducted according to the following procedure:
(a)
(b)
(c)
The bonfire test is conducted with a completely cooled-down container
(according to the procedure in Paragraph 7.4.2.1.);
The container contained during the previous 24h a volume of liquid hydrogen at
least equal to half of the water volume of the inner container;
The container is filled with liquid hydrogen so that the quantity of liquid hydrogen
measured by the mass measurement system is half of the maximum allowed
quantity that may be contained in the inner container;

7.4.4.1. Pressure Test
A hydrogen containing component shall withstand without any visible evidence of leak
or deformation a test pressure of 150% MAWP with the outlets of the high pressure
part plugged. The pressure shall subsequently be increased from 150% to 300%
MAWP. The component shall not show any visible evidence of rupture or cracks.
The pressure supply system shall be equipped with a positive shut-off valve and a
pressure gauge having a pressure range of not less than 150% and no more than 200%
of the test pressure; the accuracy of the gauge shall be 1% of the pressure range.
For components requiring a leakage test, this test shall be performed prior to the
pressure test.
7.4.4.2. External Leakage Test
A component shall be free from leakage through stem or body seals or other joints, and
shall not show evidence of porosity in casting when tested as described in Paragraph
7.4.4.3.3. at any gas pressure between zero and its MAWP.
The test shall be performed on the same equipment at the following conditions:
(a)
(b)
(c)
At ambient temperature;
At the minimum operating temperature or at liquid nitrogen temperature after
sufficient conditioning time at this temperature to ensure thermal stability;
At the maximum operating temperature after sufficient conditioning time at this
temperature to ensure thermal stability.
During this test, the equipment under test shall be connected to a source of gas
pressure. A positive shut-off valve and a pressure gauge having a pressure range of
not less than 150% and not more than 200% of the test pressure shall be installed in
the pressure supply piping; the accuracy of the gauge shall be 1% of the pressure
range. The pressure gauge shall be installed between the positive shut-off valve and
the sample under test.
Throughout the test, the sample shall be tested for leakage, with a surface active agent
without formation of bubbles or measured with a leakage rate less than 216Nml/h.
7.4.4.3. Endurance Test
7.4.4.3.1. A component shall be capable of conforming to the applicable leakage test
requirements of Paragraph 7.4.4.2. and 7.4.4.9., after being subjected to
20,000 operation cycles.
7.4.4.3.2. The appropriate tests for external leakage and seat leakage, as described in
Paragraph 7.4.4.2. and 7.4.4.9. shall be carried out immediately following the
endurance test.

7.4.4.7. Ozone Ageing Test
The test shall be in compliance with ISO 1431-1. The test piece, which shall be stressed
to 20% elongation, shall be exposed to air at +40°C with an ozone concentration of 50
parts per hundred million during 120h.
No cracking of the test piece is allowed.
7.4.4.8. Temperature Cycle Test
A non-metallic part containing hydrogen shall comply with the leakage tests referred to
in Paragraph 7.4.4.2. and 7.4.4.9. after having been submitted to a 96h temperature
cycle from the minimum operating temperature up to the maximum operating
temperature with a cycle time of 120mins, under MAWP.
7.4.4.9. Flex Line Cycle Test
Any flexible fuel line shall be capable of conforming to the applicable leakage test
requirements referred to in Paragraph 7.4.4.2., after being subjected to
6,000 pressure cycles.
The pressure shall change from atmospheric pressure to the MAWP of the container
within less than 5s, and after a time of at least 5s, shall decrease to atmospheric
pressure within less than 5s.
The appropriate test for external leakage, as referred to in Paragraph 7.4.4.2., shall be
carried out immediately following the endurance test.
7.5. Test Procedures for LHSS Fuel System Integrity
7.5.1. Post-crash Leak Test for the Liquefied Hydrogen Storage Systems
Prior to the vehicle crash test, the following steps are taken to prepare the liquefied
hydrogen storage system (LHSS):
(a)
If the vehicle does not already have the following capabilities as part of the
standard vehicle, and tests in Paragraph 6.1.1. are to be performed; the following
shall be installed before the test:
(i)
(ii)
(iii)
LHSS pressure sensor. The pressure sensor shall have a full scale of
reading of at least 150% of MAWP, an accuracy of at least 1% of full scale,
and capable of reading values of at least 10kPa;
LHSS temperature sensor. The temperature sensor shall be capable of
measuring cryogenic temperatures expected before crash. The sensor is
located on an outlet, as near as possible to the container;
Fill and drain ports. The ability to add and remove both liquefied and
gaseous contents of the LHSS before and after the crash test shall be
provided.

Prior to the test the manufacturer shall provide a list of all possible leaking parts of the
LHSS. Possible leaking parts are:
(a)
(b)
(c)
(d)
(e)
Any connectors between pipes and between pipes and the container;
Any welding of pipes and components downstream the container;
Valves;
Flexible lines;
Sensors.
Prior to the leak test overpressure in the LHSS shall be released to atmospheric
pressure and afterwards the LHSS shall be pressurised with helium to at least the
operating pressure but well below the normal pressure control setting (so the pressure
regulators do not activate during the test period). The test is passed if the total leakage
amount (i.e. the sum of all detected leakage points) is less than 216Nml/h.
7.5.1.2. Alternative Post-crash Tests for the Liquefied Hydrogen Storage Systems.
Both tests of Paragraph 7.5.1.2.1. and 7.5.1.2.2. are conducted under the test
procedure of Paragraph 7.5.1.2.
7.5.1.2.1. Alternative Post-crash Leak Test
Following confirmation that the pressure control and/or safety relief valves are still
functional, the following test may be conducted to measure the post-crash leakage. The
concentration test in Paragraph 6.1.1.1. shall be conducted in parallel for the 60min
test period if the hydrogen concentration has not already been directly measured
following the vehicle crash.
The container shall be vented to atmospheric pressure and the liquefied contents of
the container shall be removed and the container shall be heated up to ambient
temperature. The heat-up could be done, e.g. by purging the container sufficient times
with warm nitrogen or increasing the vacuum pressure.
If the pressure control set point is less than 90% of the MAWP, the pressure control
shall be disabled so that it does not activate and vent gas during the leak test.
The container shall then be purged with helium by either:
(a)
(b)
Flowing at least 5 volumes through the container; or
Pressurising and de-pressurising the container the LHSS at least 5 times.

Hydrogen and Fuel Cell Vehicles.