Date: 2025-11-25

ISO/DIS 15500-7:2026(en)

ISO TC 22/SC 41/WG 3

Secretariat: UNI

Road vehicles — Compressed natural gas (CNG) fuel system components — Part 7: Gas injector

Véhicules routiers -- Composants des systèmes de combustible gaz naturel comprimé (GNC) -- Partie 7: Injecteur de gaz

© ISO 2026

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Road vehicles — Compressed natural gas (CNG) fuel system components — Part 7: Gas injector

This part of ISO 15500 specifies tests and requirements for the gas injector and/or fuel rail, a compressed natural gas fuel system component intended for use on the types of motor vehicles defined in ISO 3833.

This part of ISO 15500 is applicable to vehicles using natural gas in accordance with ISO 15403‑1 (mono-fuel, bi-fuel, or dual-fuel applications). It is not applicable to injectors intended for high-pressure injection to the combustion chamber, or 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.

NOTE 1 It is recognized that miscellaneous components not specifically covered herein can be examined to meet the criteria of this part of ISO 15500 and tested according to the appropriate functional tests.

NOTE 2 All references to pressure in this part of ISO 15500 are to be considered gauge pressures unless otherwise specified.

NOTE 3 This part of ISO 15500 is based upon a service pressure for natural gas 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.

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 15500‑1, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 1: General requirements and definitions

ISO 15500‑2:—,^[2] 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 terminological 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

duty cycle

percentage of time that the gas injector is operating in the period

3.2

period

P

time elapsed between the beginning of one injection pulse and the beginning of the next injection pulse

Note 1 to entry: It is expressed in milliseconds.

3.3

fuel rail assembly

component consisting of gas injector(s) and fuel rail integrated into one component

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 working pressure and temperature range.

The following additional markings are recommended:

— the direction of flow (when necessary for correct installation);

— the type of fuel;

— electrical ratings (if applicable);

— the symbol of the certification agency;

— the type approval number;

— the serial number or date code;

— a reference to this part of ISO 15500.

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.

5.1 The gas injector shall be in the closed position when de-energized.

5.2 The gas injector 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 — Test applicable

This test has two parts, with the procedures to be carried out in the sequence as given below.

a) Apply two times the working pressure to the inlet and outlet of the gas injector and/or fuel rail for a period of at least 3 min. On completion of this procedure, the gas injector and/or fuel rail shall remain gas-tight.

b) Increase the gas pressure from two times the working pressure up to a maximum of four times the working pressure, until such time as the gas injector and/or fuel rail leaks or bursts.

On completion of this procedure, the gas injector and/or fuel rail shall not have burst before leaking.

NOTE If the gas injector fails in the closed position due to its construction, then it is considered to have passed both parts of this test.

The test samples used for this test shall not be used for any other tests.

Prior to this test, the gas injector or fuel rail assembly shall pass the leakage test in accordance with ISO 15500‑2:—, Clause 6, and the insulation resistance test given in 6.4.

Subject the gas injector or fuel rail assembly to 600 × 10⁶ pulses at working pressure and room temperature. This procedure may be interrupted at 20 % intervals in order to check test criteria.

The minimum frequency for the pulses shall be 50 Hz.

Upon completion of this test, the gas injector or fuel rail assembly shall pass the leakage test in accordance with ISO 15500‑2:—, Clause 6, and the insulation resistance test given in 6.4.

Hot static

Connect the injector or fuel rail assembly to an appropriate source of pressurized test gas at its working pressure, then expose the pressurized gas injector or fuel rail assembly to an environment with a stabilized temperature of 140 °C ± 2 °C for 16 h. The gas injector or fuel rail assembly shall not be operated during this test.

Cold static

Connect the injector or fuel rail assembly to an appropriate source of pressurized test gas at its working pressure, then expose the pressurized gas injector or fuel rail assembly to an environment with a stabilized temperature of –40 °C ± 2 °C or -20 °C ± 2 °C, as applicable for 16 h. The gas injector shall not be operated during this test.

Thermocycle

Connect the injector or fuel rail assembly to an appropriate source of pressurized test gas at its working pressure, then expose the pressurized gas injector or fuel rail assembly to the thermocycle in accordance with Figure 1 for a total of 140 cycles. The gas injector or fuel rail assembly shall be operated only during segment D to E as shown in Figure 1 with a 50 % duty cycle and a period of 10 ms.

^a Repeat cycle.

NOTE Specified temperatures have a tolerance of ±2 °C.

Figure 1 — Thermocycle

Requirements

Upon completion of the procedures given in 6.3.2.1, 6.3.2.2 and 6.3.2.3, the test samples shall pass the leakage test in accordance with ISO 15500‑2:—, Clause 6, and the insulation resistance test given in 6.4.

This test is designed for checking the insulation resistance between the connector pin and the housing.

Apply a test voltage of 500 V d.c. for a duration of 60 s; for injectors with circuitry of 3,8 mm pitch or below, 100 V d.c. shall be used.

The minimum allowable resistance shall be >10 MΩ.

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, 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. To be published. (Revision of ISO 15500-2:2012). ↑