ISO 15500-9:2020

Road vehicles - Compressed natural gas (CNG) fuel system components - Part 9: Pressure regulator

This document specifies tests and requirements for the pressure regulator, a compressed natural gas (CNG) fuel system component intended for use on the types of motor vehicles defined in ISO 3833. This document is applicable to vehicles (mono-fuel, bi-fuel or dual-fuel applications) using natural gas in accordance with the ISO 15403 series 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 9: Régulateur de pression

General Information

• Status: Published
• Publication Date: 02-Aug-2020
• 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: 14-Feb-2023
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 15500-9:2012 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 9: Pressure regulator
• Effective Date: 09-Jun-2018
• Revises: ISO 15500-9:2012/Amd 1:2016 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 9: Pressure regulator - Amendment 1
• Effective Date: 09-Jun-2018

Overview - ISO 15500-9:2020 (CNG Pressure Regulator)

ISO 15500-9:2020 is the international standard that specifies tests and performance requirements for pressure regulators used in compressed natural gas (CNG) fuel systems for road vehicles (as defined in ISO 3833). It applies to mono‑fuel, bi‑fuel and dual‑fuel vehicle applications using natural gas in accordance with the ISO 15403 series. The standard defines marking, construction, and a comprehensive test program to ensure regulator safety and durability in vehicle service.

Key exclusions: LNG components upstream of and including the vaporizer, fuel containers, stationary gas engines, container‑mounting hardware, electronic fuel management and refuelling receptacles.

Key topics and technical requirements

• Marking and traceability: Manufacturer name/trademark, model/part number, working pressure and temperature range, maximum outlet pressure, and serial number/date code are required; additional identifiers (flow direction, electrical ratings, type approval) are recommended.
• Construction and assembly: Regulators must meet ISO 15500‑1 and ISO 15500‑2 provisions; downstream components must be protected from full upstream pressure (resetting pressure relief valve required).
• Hydrostatic strength: First‑stage inlet tested at 2.5× working pressure; downstream chambers tested at 2.5× relief valve set pressure (or upstream working pressure if no relief valve); multi‑stage outlet chambers/fittings tested at 2.5× working pressure or 0.4 MPa (4 bar), whichever is greater.
• External leakage: Leak tests across defined temperature and pressure ranges (including extreme cold and high temperature conditions).
• Continued operation (durability): Regulators must survive 50 000 cycles under specified temperature and pressure cycling without failure; lock‑up pressure must remain within manufacturer limits.
• Electrical tests (where applicable):
  • Insulation resistance: 1 000 V DC applied; minimum 240 kΩ.
  • Minimum opening voltage: ≤8 V for 12 V systems, ≤16 V for 24 V systems (other voltages tested at ≤66% nominal).
• Pressure impulse tests: Internal and external impulse tests to verify resistance to instantaneous pressure spikes (e.g., when filling an empty system).
• Water jacket freezing: Freeze/thaw conditioning to validate antifreeze/water jacket integrity and subsequent leak tightness.

Applications and users

This standard is essential for:

• CNG regulator manufacturers and component designers (design verification and type approval)
• Automotive OEMs integrating CNG systems into vehicles
• Test laboratories and conformity assessment bodies performing type testing
• Certification agencies and regulatory authorities setting vehicle fuel‑system safety requirements
• Fleet operators and maintenance engineers specifying compliant replacement parts

Related standards

• ISO 15500‑1: General requirements and definitions
• ISO 15500‑2: Performance and general test methods
• ISO 15403 series: Natural gas fuel quality
• ISO 3833: Road vehicle categories

Keywords: ISO 15500‑9, CNG pressure regulator, compressed natural gas regulator, CNG fuel system components, pressure regulator testing, hydrostatic strength, insulation resistance, pressure impulse.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15500-9
Third edition
2020-08
Road vehicles — Compressed natural
gas (CNG) fuel system components —
Part 9:
Pressure regulator
Véhicules routiers — Composants des systèmes de combustible gaz
naturel comprimé (GNC) —
Partie 9: Régulateur de pression
Reference number
©
ISO 2020
© ISO 2020
All rights reserved. Unless otherwise specified, or required in the context of its implementation, 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
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Marking . 2
5 Construction and assembly . 2
6 Tests . 2
6.1 Applicability . 2
6.2 Hydrostatic strength . 3
6.3 External leakage . 3
6.4 Continued operation . 4
6.5 Insulation resistance . 4
6.6 Minimum opening voltage . 4
6.7 Pressure impulse . 5
6.7.1 Internal impulse . 5
6.7.2 External impulse . 5
6.8 Water jacket freezing . 5
Bibliography . 6
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
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For an explanation of the voluntary nature of standards, 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 www .iso .org/
iso/ foreword .html.
This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 41,
Specific aspects for gaseous fuels.
This third edition cancels and replaces the second edition (ISO 15500-9:2012), which has been
technically revised. It also incorporates the Amendment ISO 15500-9:2012/Amd.1:2016. The main
changes compared to the previous edition are as follows:
— update of Clause 4 (Marking);
— update of Clause 6 (Test operation).
A list of all parts in the ISO 15500 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/ members .html.
iv © ISO 2020 – All rights reserved

Introduction
For the purposes of this document, all fuel system components in contact with natural gas have been
considered suitable for natural gas as defined in the ISO 15403 series. However, it is recognized that
miscellaneous components not specifically covered herein can be examined to meet the criteria of this
document and tested according to the appropriate functional tests.
All references to pressure in this document are considered to be gauge pressures unless otherwise
specified.
1)
This document 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 .
INTERNATIONAL STANDARD ISO 15500-9:2020(E)
Road vehicles — Compressed natural gas (CNG) fuel system
components —
Part 9:
Pressure regulator
1 Scope
This document specifies tests and requirements for the pressure regulator, a compressed natural gas
(CNG) fuel system component intended for use on the types of motor vehicles defined in ISO 3833.
This document is applicable to vehicles (mono-fuel, bi-fuel or dual-fuel applications) using natural gas in
accordance with the ISO 15403 series
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 are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 15500-1, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 1: General
requirements and definitions
ISO 15500-2, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 2:
Performance and ge
...