ISO 15500-14:2020

Road vehicles - Compressed natural gas (CNG) fuel system components - Part 14: Excess flow valve

This document specifies tests and requirements for the excess flow valve, 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 14: Valve de limitation de débit

General Information

• Status: Published
• Publication Date: 14-Sep-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 15500-14:2012 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 14: Excess flow valve
• Effective Date: 09-Jun-2018
• Revises: ISO 15500-14:2012/Amd 1:2016 - Road vehicles - Compressed natural gas (CNG) fuel system components - Part 14: Excess flow valve - Amendment 1
• Effective Date: 09-Jun-2018

Overview

ISO 15500-14:2020 is an international standard specifying requirements and test methods for excess flow valves used in compressed natural gas (CNG) fuel systems for road vehicles. This standard is part 14 of the ISO 15500 series, which focuses on CNG fuel system components. It applies to mono-fuel, bi-fuel, and dual-fuel motor vehicles utilizing natural gas as defined by ISO 15403.

The excess flow valve is a crucial safety component designed to limit or shut off gas flow in the event of a sudden pressure surge or line rupture. ISO 15500-14:2020 defines the construction, marking, testing, and performance criteria necessary to ensure reliable operation and safety in CNG fuel systems.

Key Topics

• Scope and Application: Covers excess flow valves for road vehicles compliant with ISO 3833 vehicle definitions. Exclusions include LNG components upstream of the vaporizer, fuel containers, stationary engines, refuelling receptacles, and electronic fuel management systems.

• Valve Types:

  • Internal excess flow valves: Installed inside cylinders or cylinder valves.
  • External excess flow valves: Installed outside the cylinder or valve assembly.
  • Shut-off type: Completely stops flow upon activation.
  • Flow-limiter type: Limits flow and resets automatically once the excess flow condition is resolved.

• Marking Requirements: Must include manufacturer identification, model number, operating specifications (pressure, temperature range, valve type, activation flow), and serial or data codes. Additional markings such as flow direction, fuel type, certification symbols, and type approval references are recommended.

• Construction and Assembly: Must comply with general provisions from ISO 15500-1 and ISO 15500-2 standards, with tolerance levels tailored accordingly.

• Testing Protocols:

  • Hydrostatic strength testing at 2.5 times working pressure to verify housing integrity.
  • Leakage testing on activated shut-off valves across varying temperatures and pressures.
  • Excess torque resistance and bending moment tests specific to external valves.
  • Cycling for 20 operational cycles under working pressure conditions to ensure durability.
  • Functional operation test to measure activation flow rate and pressure differential.
  • Pressure impulse durability testing with 100 pulses in both flow directions.

These tests ensure valve functionality under different environmental and operating conditions reflective of real-world use.

Applications

ISO 15500-14:2020 applies primarily to the automotive and transportation sectors focusing on natural gas-powered vehicles. Its practical value includes:

• Enhanced Safety: Protects against gas leaks and uncontrolled fuel release following accidents or system failures by triggering valve closure or flow reduction.
• Regulatory Compliance: Assists manufacturers and suppliers in meeting international safety and performance requirements for CNG vehicle components.
• Fuel System Integrity: Supports reliability and longevity of CNG fuel systems through rigorous testing of excess flow valves under mechanical stress and environmental exposure.
• Design Guidance: Provides clear criteria for the design and manufacture of excess flow valves, ensuring interoperability and traceability in global markets.

This standard is specifically designed to support natural gas vehicles using compressed natural gas in accordance with ISO 15403 qualities, promoting cleaner and safer alternative fuel options.

Related Standards

• ISO 15500 Series: General requirements and test methods for CNG fuel system components.
• ISO 3833: Definitions of vehicle types relevant to the application scope.
• ISO 15403-1 and ISO/TR 15403-2: Specifications of natural gas quality suitable for vehicle fuel systems.

These standards collectively establish a comprehensive framework ensuring safety, quality, and performance across all CNG fuel system components.

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Keywords: ISO 15500-14, excess flow valve, compressed natural gas, CNG fuel system, vehicle safety, valve testing, natural gas vehicles, automotive standards, ISO standards, valve marking, hydrostatic strength, leakage test, flow limiter, shut-off valve.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15500-14
Third edition
2020-09
Road vehicles — Compressed natural
gas (CNG) fuel system components —
Part 14:
Excess flow valve
Véhicules routiers — Composants des systèmes de combustible gaz
naturel comprimé (GNC) —
Partie 14: Valve de limitation de débit
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
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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 Leakage . 3
6.4 Excess torque resistance . 4
6.5 Bending moment . 4
6.6 Continued operation . 4
6.7 Operation . 4
6.8 Pressure impulse . 4
Bibliography . 5
Foreword
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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 15500-14:2012), which has been
technically revised. It also incorporates the Amendment ISO 15500-14:2012/Amd.1:2016. The main
changes compared to the previous edition are as follows:
— update of Clause 4 (Marking);
— update of 6.3 (Leakage test).
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 =
...