ISO 15500-2:2016

Road vehicles - Compressed natural gas (CNG) fuel system components - Part 2: Performance and general test methods

ISO 15500-2:2016 specifies performance and general test methods for compressed natural gas (CNG) fuel system components intended for use on the types of motor vehicles defined in ISO 3833. ISO 15500-2:2016 is applicable to vehicles (mono-fuel, bi-fuel or dual-fuel applications) using compressed natural gas in accordance with ISO 15403 (all parts). It is not applicable to the following: a) liquefied natural gas (LNG) fuel system components located upstream of, and including, the vaporizer; b) fuel containers; c) stationary gas engines; d) container-mounting hardware; e) electronic fuel management; f) refuelling receptacles.

Véhicules routiers — Composants des systèmes de combustible gaz naturel comprimé (GNC) — Partie 2: Performances et méthodes d'essai générales

General Information

• Status: Published
• Publication Date: 20-Apr-2016
• ICS: 43.060.40 - Fuel systems
• Technical Committee: ISO/TC 22/SC 41 - Specific aspects for gaseous fuels
• Drafting Committee: ISO/TC 22/SC 41/WG 3 - Fuel system components and refuelling connector for vehicles propelled by gaseous fuel
• Current Stage: 9092 - International Standard to be revised
• Start Date: 29-Nov-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 15500-2:2012 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 2: Performance and general test methods
• Effective Date: 05-Nov-2015

Overview

ISO 15500-2:2016 - "Road vehicles - Compressed natural gas (CNG) fuel system components - Part 2: Performance and general test methods" - defines performance criteria and general test methods for CNG fuel system components intended for motor vehicles (as defined in ISO 3833). It applies to mono‑fuel, bi‑fuel and dual‑fuel vehicles that use compressed natural gas in accordance with ISO 15403 (all parts). The standard excludes LNG components upstream of the vaporizer, fuel containers, stationary engines, container‑mounting hardware, electronic fuel management and refuelling receptacles.

Key topics and technical requirements

• Test environment and media
  • Default room temperature: 20 °C ± 5 °C unless otherwise stated.
  • Tests are normally conducted using dry air or nitrogen; natural gas may be used with safety precautions.
• Hydrostatic strength
  • Components are pressure‑tested to failure; pressure increase rate and failure recording are specified. Previously tested samples must not show failure pressure less than 80% of virgin samples.
• Leakage (external and internal)
  • Bubble immersion tests or helium vacuum/global accumulation methods are accepted for detection.
  • Components must meet specified leakage limits (see Clause 6.1.2); conditioning and temperature states are defined.
• Mechanical and durability tests
  • Excess torque resistance: threaded components must withstand at least 150% of rated installation torque without deformation, followed by leakage and hydrostatic checks.
  • Bending moment, vibration resistance, continued operation (temperature cycling: room, high, low), and corrosion resistance.
• Materials and ageing
  • Tests include ozone ageing, oxygen ageing, resistance to dry heat, automotive fluid exposure, non‑metallic material immersion, and brass compatibility.
• Electrical and other tests
  • Electrical over‑voltages and other functional safety checks where applicable.
• Service pressure baseline
  • Service pressure is based on 20 MPa (200 bar) at 15 °C; other pressures can be scaled (e.g., 25 MPa requires a factor of 1.25).

Applications and users

Who uses ISO 15500-2:2016:

• CNG component manufacturers and suppliers (valves, regulators, fittings, lines)
• Automotive OEMs and powertrain engineers integrating CNG systems
• Independent test laboratories and certification bodies performing conformity testing
• Regulatory authorities and fleet operators seeking harmonized safety and performance criteria

Benefits:

• Ensures safety, reliability and interoperability of CNG components
• Facilitates market access through common test methods and acceptance criteria
• Helps designers validate materials and mechanical integrity under real‑world conditions

Related standards

• ISO 15500‑1:2015 (General requirements and definitions)
• Other parts of ISO 15500 (Parts 3–20 covering specific components)
• ISO 3833 (vehicle classification)
• ISO 15403 (natural gas fuel specifications)
• Normative references cited: ISO 188, ISO 1431‑1, ISO 1817, ISO 9227

Keywords: ISO 15500-2:2016, CNG fuel system components, compressed natural gas standard, CNG testing, hydrostatic strength, leakage test, vehicle CNG components.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15500-2
Third edition
2016-05-01
Road vehicles — Compressed natural
gas (CNG) fuel system components —
Part 2:
Performance and general test methods
Véhicules routiers — Composants des systèmes de combustible gaz
naturel comprimé (GNC) —
Partie 2: Performances et méthodes d’essai générales
Reference number
©
ISO 2016
© ISO 2016, Published in Switzerland
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form
or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior
written permission. Permission can be requested from either ISO at the address below or ISO’s member body in the country of
the requester.
ISO copyright office
Ch. de Blandonnet 8 • CP 401
CH-1214 Vernier, Geneva, Switzerland
Tel. [phone]
Fax [phone]
[e-mail]
www.iso.org
ii © ISO 2016 – All rights reserved

Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 1
5 Hydrostatic strength . 2
6 Leakage. 2
6.1 General . 2
6.2 External leakage . 2
6.3 Internal leakage . 3
6.4 Test conditions . 3
7 Excess torque resistance . 3
8 Bending moment . 4
9 Continued operation. 5
9.1 General . 5
9.2 Test methods . 5
9.2.1 Test procedure . 5
9.2.2 Room temperature cycling . 6
9.2.3 High-temperature cycling . 6
9.2.4 Low-temperature cycling . 6
10 Corrosion resistance . 6
11 Oxygen ageing . 6
12 Electrical over-voltages . 7
13 Non-metallic material immersion . 7
14 Vibration resistance . 8
15 Brass material compatibility . 8
16 Ozone ageing for vulcanized or thermoplastic rubbers . 8
17 Resistance to dry heat for vulcanized or thermoplastic rubbers . 9
18 Automotive fluid exposure . 9
18.1 General . 9
18.2 Test Method . 9
18.3 Fluids . 9
18.4 Pass criteria . 9
Bibliography .10
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
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ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO’s adherence to the World Trade Organization (WTO) principles in the
Technical Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.
The committee responsible for this document is ISO/TC 22, Road vehicles, Subcommittee SC 41, Specific
aspects for gaseous fuels.
This third edition cancels and replaces the second edition (ISO 15500-2:2012), which has been
technically revised.
ISO 15500 consists of the following parts, under the general title Road vehicles — Compressed natural
gas (CNG) fuel system components:
— Part 1: General requirements and definitions
— Part 2: Performance and general test methods
— Part 3: Check valve
— Part 4: Manual valve
— Part 5: Manual cylinder valve
— Part 6: Automatic valve
— Part 7: Gas injector
— Part 8: Pressure indicator
— Part 9: Pressure regulator
— Part 10: Gas-flow adjuster
— Part 11: Gas/air mixer
— Part 12: Pressure relief valve (PRV)
— Part 13: Pressure relief device (PRD)
iv © ISO 2016 – All rights reserved

— Part 14: Excess flow valve
— Part 15: Gas-tight housing and ventilation hose
— Part 16: Rigid fuel line in stainless steel
— Part 17: Flexible fuel line
— Part 18: Filter
— Part 19: Fittings
— Part 20: Rigid fuel line in material other than stainless steel
Introduction
For the purposes of this part of ISO 15500, all fuel system components in contact with natural gas have
been considered suitable for natural gas as defined in ISO 15403 (all parts). However, it is recognized
that miscellaneous components not specifically covered herein can be examined to meet the criteria of
this part of ISO 15500 and can be tested in accordance with the appropriate functional tests.
All references to pressure in this part of ISO 15500 are considered to be gauge pressures unless
otherwise specified.
1)
This part of ISO 15500 is based on a service pressure for natural gas used as fuel of 20 MPa (200 bar ),
settled at 15 °C. Other service pressures can be accommodated by adjusting the pressure by the
appropriate factor (ratio). For example, a 25 MPa (250 bar) service pressure system will require
pressures to be multiplied by 1,25.
5 2
1) 1 bar = 0,1 MPa = 10 Pa; 1 MPa = 1 N/mm .
vi © ISO 2016 – All rights reserved

INTERNATIONAL STANDARD ISO 15500-2:2016(E)
Road vehicles — Compressed natural gas (CNG) fuel system
components —
Part 2:
Performance and general test methods
1 Scope
This part of ISO 15500 specifies performance and general test methods for compressed natural gas
(CNG) fuel system components intended for use on the types of motor vehicles defined in ISO 3833.
This part of ISO 15500 is applicable to vehicles (mono-fuel, bi-fuel or dual-fuel applications) using
compressed natural gas in accordance with ISO 15403 (all parts). It is not applicable to the following:
a) liquefied natural gas (LNG) fuel system components located upstream of, and including, the
vaporizer;
b) fuel containers;
c) stationary gas engines;
d) container-mounting hardware;
e) electronic fuel management;
f) refuelling receptacles.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 188, Rubber, vulcanized or thermoplastic — Accelerated ageing and heat resistance tests
ISO 1431-1, Rubber, vulcanized or thermoplastic — Resistance to ozone cracking — Part 1: Static and
dynamic strain testing
ISO 1817, Rubber, vulcanized or thermoplastic — Determination of the effect of liquids
ISO 9227, Corrosion tests in artificial atmospheres — Salt spray tests
ISO 15500-1:2015, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 1:
General requirements and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15500-1 apply.
4 General
4.1 Unless otherwise stated, the tests shall be conducted at a room temperature of 20 °C ± 5 °C.
4.2 Components shall comply with the tests specified in this part of ISO 15500 as well as the relevant
parts of ISO 15500, as applicable for each component.
NOTE Because of the peculiarities of some components, the list of tests given in this part of ISO 15500,
(Clauses 5 to 15) is not exhaustive. Where additional tests are required, their provisions are given in other parts
of ISO 15500.
4.3 Unless otherwise specified, all tests shall be conducted using dry air or nitrogen. Tests may also
be conducted with natural gas provided appropriate safety measures are taken. The dew point of the
test gas at the test pressure shall be at the temperature at which there is no icing, or hydrate or liquid
formation.
Unless otherwise specified, all pressures shall have a maximum tolerance of ±5 %.
Unless otherwise specified, all temperatures shall have a maximum tolerance of ±5 %.
Unless otherwise specified, all dimensions shall have a maximum tolerance of ±5 %.
5 Hydrostatic strength
A component shall not show any visible evidence of rupture when subjected to the following test
procedure.
Plug the outlet opening of the component and have the valve seats or internal blocks assume the open
position. Apply, with a test fluid, the hydrostatic pressure specified in the applicable part of ISO 15500
to the inlet of the component for a period of at least 3 min.
The hydrostatic pressure shall then be increased at a rate of less than or equal to 1,4 MPa/s until
component failure. The hydrostatic pressure at failure shall be recorded. The failure pressure of
previously tested components shall be no less than 80 % of the failure pressure of the virgin component.
The samples used in this test shall not be used for any other testing.
6 Leakage
6.1 General
6.1.1 Prior to conditioning, purge the component with nitrogen, then seal it at 30 % of the working
pressure using nitrogen, dry air or natural gas.
6.1.2 Conduct all tests while the device is continuously exposed to the specified test temperatures. The
device shall either be bubble-free or display a leakage rate of less than 20 Ncm /h when subjected to the
following test method.
If components are subjected to more than one working pressure, the test may be conducted in
subsequent steps.
6.2 External leakage
6.2.1 Plug each device outlet into the appropriate mating connection.
6.2.2 Apply pressurized air, nitrogen or natural gas to the inlet of the test device.
 
+30
6.2.3 At all test temperatures, immerse the components in a suitable test medium for 2 min s or
 
 
use a helium vacuum test (global accumulation method) or other equivalent method.
2 © ISO 2016 – All rights reserved

6.2.4 If there are no bubbles for the specified time period, the sample passes the test. If bubbles are
detected, measure the leakage rate using an appropriate method; the leakage rate should not be more
than that specified in 6.1.2.
6.3 Internal leakage
6.3.1 The internal leakage test is applicable only to devices in the closed position. The aim of this test is
to check the pressure tightness of the closed system.
6.3.2 Connect the inlet or outlet (as applicable) of the device to the appropriate mating
...