ISO 15500-7:2015

Overview

ISO 15500-7:2015 defines tests and requirements for gas injectors and fuel rails used in compressed natural gas (CNG) road-vehicle fuel systems. Part 7 of the ISO 15500 series applies to mono‑fuel, bi‑fuel and dual‑fuel vehicle applications using natural gas per ISO 15403‑1 and is intended for motor vehicles defined in ISO 3833. The standard is based on a reference service pressure of 20 MPa (200 bar) at 15 °C, with scalable test pressures for higher service pressures.

Key topics and technical requirements

• Scope and exclusions: Covers injectors/fuel rails but excludes high‑pressure direct‑to‑chamber injectors, LNG components upstream of the vaporizer, fuel containers, stationary engines, refuelling receptacles, electronic fuel management and mounting hardware.
• Marking and identification: Components must be traceable (manufacturer, part number, working pressure and temperature range). Additional markings (flow direction, fuel type, electrical ratings, certification symbol, serial/date code) are recommended.
• Construction requirement: The gas injector shall be closed when de‑energized.
• Mandatory tests (aligned with ISO 15500‑2 procedures):
  • Pneumatic strength: Two‑stage test - hold at 2× working pressure for ≥3 min (must remain gas‑tight), then increase up to 4× working pressure until leak or burst (must leak before burst).
  • Leakage, excess torque, bending moment, corrosion and material compatibility tests.
  • Continued operation / bench durability: High‑cycle operational durability test at working pressure (specified pulse count and minimum 50 Hz pulse frequency).
  • Temperature tests: Hot static (140 °C ±2 °C for 16 h), cold static (–40 °C or –20 °C ±2 °C for 16 h), and a thermocycle of 140 cycles with operation during specified segments (50 % duty cycle, 10 ms period).
  • Insulation resistance: 500 V DC for 60 s (100 V DC for connector pitch ≤3.8 mm); minimum resistance > 10 MΩ.
• Pressure scaling: Test pressures can be adjusted proportionally for systems with service pressures other than 20 MPa (example: 25 MPa → multiply pressures by 1.25).

Applications and who uses it

ISO 15500-7 is used by:

• CNG component manufacturers for design, production control and type approval of gas injectors and fuel rails.
• Automotive OEMs and system integrators ensuring component compatibility and safety in CNG vehicles.
• Test laboratories and certification bodies executing standardized pneumatic, thermal and electrical tests.
• Regulators and fleet operators evaluating conformity and reliability of CNG fuel system components. Practical uses include product validation, safety assessments, supplier specification, and compliance for vehicle homologation.

Related standards

• ISO 15500 series (Parts 1–20) - general CNG fuel system requirements and other components
• ISO 15500-1 (general requirements), ISO 15500-2 (performance & test methods)
• ISO 3833 (vehicle type definitions)
• ISO 15403‑1 (natural gas quality for vehicles)

Keywords: ISO 15500-7, CNG gas injector standard, compressed natural gas, gas injector testing, fuel rail, pneumatic strength, insulation resistance.