Road vehicles — Compressed natural gas (CNG) fuel system components-

Part 7: Gas injector

1.Scope

This part of ISO 15500 specifies tests and requirements for the gas injector, 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 (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 [ ] settled at . Other service pressures can be accommodated by adjusting the pressure by the appropriate factor (ratio). For example, a [ ] service pressure system will require pressures to be multiplied by 1,25.

NOTE 4 ; .

2 Normative references

The following normative documents contain provisions which, through reference in this text, constitute provisions of this part of ISO 15500. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this part of ISO 15500 are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards.

  • ISO 3833:1977, Road vehicles — Types — Terms and definitions
  • SO 15500-1, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 1: General requirements and definitions
  • SO 15500-2, Road vehicles — Compressed natural gas (CNG) fuel system components — Part 2: Performance and general test methods
  • ISO 15403, Natural gas — Designation of the quality of natural gas for use as a compressed fuel for vehicles

3 Terms and definitions

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

3.1 Duty cycle

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

3.2 period

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

NOTE It is expressed in milliseconds.

4 Marking

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

  • the manufacturer's or agent's name, trademark or symbol;
  • the model designation (part number);
  • the service pressure or pressure and temperature range

The following additional markings are recommended:

  • d) the direction of flow (when necessary for correct installation);
  • e) the type of fuel;
  • f) electrical ratings (if applicable);
  • g) the symbol of the certification agency;
  • h) the type approval number;
  • i) the serial number or date code;
  • j) the 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 Construction and assembly

5.1

5 Construction and assembly

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 of this part of ISO 15500.

6 Tests

6.1 Applicability

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

6.2 Pneumatic strength

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

  • a) Plug the outlet opening of the gas injector and have the valve seat or internal blocks assume the open position. Apply two times the working pressure to the inlet of the gas injector for a period of at least . On completion of this procedure, the gas injector shall remain gas-tight.
  • a) Plug the outlet opening of the gas injector and have the valve seat or internal blocks assume the open position. Apply two times the working pressure to the inlet of the gas injector for a period of at least . On completion of this procedure, the gas injector shall remain gas-tight.

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.

6.3 Continued operation

6.3.1 Bench durability

Prior to this test, the gas injector shall pass the leakage test in accordance with ISO 15500-2:2001, clause 6, and the insulation resistance test given in this part of ISO 15500 (see 6.4).

Subject the gas injector to pulses at working pressure and room temperature. This procedure may be interrupted at intervals in order to check test criteria.

Upon completion of this test, the gas injector shall pass the leakage test in accordance with ISO 15500-2:2001, clause 6, and the insulation resistance test given in this part of ISO 15500 (see 6.4).

ISO 15500-7:2002(E)

6.3.2 Temperature

6.3.2.1 Hot static

Expose the gas injector to a stabilized ambient temperature of for . The gas injector shall not be operated during this test.

6.3.2.2 Cold static

Expose the gas injector to a stabilized ambient temperature of for . The gas injector shall not be operated during this test.

6.3.2.3 Thermocycle

Expose the gas injector to the thermocycle in accordance with Figure 1 for a total of 140 cycles. The gas injector shall be operated only during segment D to E as shown in Figure 1 with a duty cycle and a period of .

Figure 1 — Thermocycle

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 15500-2:2001, clause 6, and the insulation resistance test given in this part of ISO 15500 (see 6.4).

6.4 Insulation resistance

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

Apply a test voltage of d.c. for a duration of . For injectors with circuitry of pitch or below, 100 V d.c. shall be used.

The minimum allowable resistance shall be .

7 Minimum opening voltage

This is an interface requirement. It shall be in line with existing petrol or diesel injector practice.