ISO/DIS 15500-23:2025(en)

ISO/TC 22/SC 41

Secretariat: UNI

Date: 2025-10-31

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

© ISO 2025

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Contents

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

Foreword

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This document was prepared by Technical Committee ISO/TC 22, Road vehicles, Subcommittee SC 41, Specific aspects for gaseous fuels.

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.

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 ISO 15403-1. 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.

This document is based on a service pressure for natural gas used as fuel of 20 MPa [200 bar^[1]] 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.

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.

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 15500‑2:2016, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 2: Performance and general test methods

For the purposes of this document, the terms and definitions given in ISO 15500-1 and the following apply.

ISO and IEC maintain terminology databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp

— IEC Electropedia: available at https://www.electropedia.org/

3.1

gas-temperature sensor

device which indicates the gas temperature

Marking of the component shall provide sufficient information to allow the following to be traced:

a) the manufacturer’s or agent’s name, trademark or symbol;

b) the model designation (part number);

c) the serial number or date code

d) the direction of flow (when necessary for correct installation).

The following additional markings are recommended:

— the working pressure or working pressure and temperature range;

— the type of fuel;

— the electrical ratings (if applicable);

— the symbol of the certification agency;

— the type approval number;

— a reference to this document.

NOTE This information can be provided by a suitable identification code on at least one part of the component when it consists of more than one part.

The gas-temperature sensor shall comply with the applicable provisions of ISO 15500-1 and ISO 15500-2, and with the tests specified in Clause 6. Tolerances should follow the specifications of ISO 15500-2.

The tests required to be carried out are indicated in Table 1.

Table 1 — Applicable tests

Test the gas-temperature sensor according to the procedure for testing hydrostatic strength specified in ISO 15500-2. The test pressure shall be 2,5 times the working pressure.

6.3.1 Test the gas-temperature sensor in accordance with the procedure for testing continued operation given in ISO 15500-2 for 15 000 pressure cycles for upstream components and 50 000 cycles for downstream components (downstream of pressure regulator). A cycle consists of pressurization to working pressure, followed by depressurization to less than 0,5 times the working pressure.

Alternatively, a gas-temperature sensor may be mounted directly to the component that it is intended to be affixed to in service, and tested according to the continuous operation test requirements for that specific component.

6.3.2 Perform the leakage test in accordance to ISO 15500-2:2016, 6.1.

This test is designed to check for a potential failure of the insulation between the pin sensor assembly and the gas temperature sensor casing.

Apply 1 000 V d.c. between one of the connector pins and the housing of the pressure indicator for at least 2 s. The minimum allowable resistance shall be > 240 kΩ.

Bibliography

[1] ISO 3833, Road vehicles — Types — Terms and definitions

[2] ISO 15403‑1, Natural gas — Natural gas for use as a compressed fuel for vehicles — Part 1: Designation of the quality

[3] ISO/TR 15403‑2,^[2] Natural gas - Natural gas for use as a compressed fuel for vehicles — Part 2: Specification of the quality

1. 1 bar = 0,1 MPa = 10⁵ Pa 1 MPa = 1 N/mm². ↑

2. This is a withdrawn document. ↑