ISO 15500-23:2023

Road vehicles - Compressed natural gas (CNG) fuel system components - Part 23: Gas temperature sensor

This document specifies tests and requirements for gas-temperature sensors, 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 ISO 15403-1. 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 remplissage en gaz naturel comprimé — Partie 23: Capteurs de température du gaz

General Information

• Status: Published
• Publication Date: 30-Aug-2023
• ICS: 43.060.40 - Fuel systems
• Technical Committee: ISO/TC 22 - Road vehicles
• Drafting Committee: ISO/TC 22 - Road vehicles
• Current Stage: 9092 - International Standard to be revised
• Start Date: 22-Dec-2024
• Completion Date: 13-Dec-2025

Overview

ISO 15500-23:2023 is an international standard specifying requirements and testing procedures for gas temperature sensors used in compressed natural gas (CNG) fuel systems on road vehicles. This standard applies to fuel system components intended for vehicles defined in ISO 3833, including mono-fuel, bi-fuel, and dual-fuel types using natural gas compliant with ISO 15403-1. The document ensures safety, reliability, and performance of gas temperature sensors in CNG systems operating at pressures typically around 20 MPa (200 bar).

This standard excludes components related to liquefied natural gas (LNG) upstream of the vaporizer, fuel containers, stationary gas engines, mounting hardware, electronic fuel management, and refuelling receptacles. ISO 15500-23 supports the development and quality assurance of CNG fuel systems by defining key design, marking, and testing criteria.

Key Topics

• Scope and Applicability
  Covers gas temperature sensors for CNG vehicles, including those running on natural gas fuels as per ISO 15403-1. Emphasis is on sensors that directly measure gas temperature within the fuel system.

• Marking Requirements
  Components must have clear markings to trace:

  • Manufacturer’s or agent’s name, trademark, or symbol
  • Model designation or part number
  • Serial number or date code
  • Direction of gas flow (if applicable)
    Additional recommended markings include working pressure and temperature ranges, fuel type, electrical ratings, certification agency symbol, and reference to this ISO standard.

• Construction and Assembly
  Gas temperature sensors must comply with general requirements and test methods defined in ISO 15500-1 and ISO 15500-2, ensuring mechanical integrity and functional accuracy.

• Testing Procedures
  A comprehensive suite of tests verifies sensor durability and safety:

  • Hydrostatic strength: Tested at 2.5 times the working pressure to ensure resistance to high pressure.
  • Continued operation: Simulates long-term pressure cycling to confirm reliability (15,000 cycles upstream, 50,000 cycles downstream of the pressure regulator).
  • Insulation resistance: Electrical testing ensures sensor insulation integrity with a minimum resistance > 240 kΩ at 1,000 V d.c.
  • Additional applicable tests include leak tightness, excess torque resistance, bending moment, corrosion, oxygen and ozone ageing, heat ageing, fluid compatibility, electrical overvoltages, vibration resistance, and material compatibility.

Applications

ISO 15500-23:2023 is essential for manufacturers, designers, and quality controllers of CNG fuel system components focusing on gas temperature sensors. Applications include:

• Automotive Industry
  Ensuring gas temperature sensors used in natural gas vehicles meet stringent performance and safety criteria. Applicable for passenger cars, commercial vehicles, and buses operating on mono- or multi-fuel configurations.

• Component Testing and Certification
  Enables testing bodies to verify compliance of new gas temperature sensors with international standards, facilitating global market access.

• Fuel System Integration
  Assists engineers integrating CNG fuel components into vehicle systems by providing reliable sensor specifications enhancing fuel system monitoring and safety.

• Aftermarket and Maintenance
  Provides guidance for replacement part manufacturers to produce certified sensors compatible with existing CNG vehicles.

Related Standards

• ISO 15500 Series
  The broader ISO 15500 family covers compressed natural gas fuel system components, including general requirements (Part 1) and performance tests (Part 2), forming the framework within which Part 23 operates.

• ISO 3833: Road Vehicles - Types - Terms and Definitions
  Defines the vehicle types applicable to this standard, ensuring appropriate component application.

• ISO 15403-1: Natural Gas for Use as Compressed Fuel
  Specifies the quality and designation of natural gas fuels compatible with the CNG systems covered by ISO 15500-23.

• ISO/TR 15403-2 (Withdrawn)
  Although withdrawn, it historically provided supplementary information regarding natural gas fuel specifications.

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Keywords: ISO 15500-23, CNG fuel system, gas temperature sensor, compressed natural gas, road vehicles, fuel system components, sensor testing, gas temperature measurement, ISO standards, natural gas vehicles, sensor marking, hydrostatic strength test, insulation resistance, vehicle fuel safety, CNG sensors compliance.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 15500-23
First edition
2023-08
Road vehicles — Compressed natural
gas (CNG) fuel system components —
Part 23:
Gas temperature sensor
Véhicules routiers — Composants des systèmes de remplissage en gaz
naturel comprimé —
Partie 23: Capteurs de température du gaz
Reference number
© ISO 2023
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
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 Continued operation . 3
6.4 Insulation resistance. 3
Bibliography . 4
iii
Foreword
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Specific aspects for gaseous fuels.
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