ISO 15500-8:2015

Overview - ISO 15500-8:2015 (Pressure indicator)

ISO 15500-8:2015 is the international standard that specifies tests and requirements for pressure indicators used in compressed natural gas (CNG) fuel system components for road vehicles. It applies to CNG systems for vehicle types defined in ISO 3833 and to vehicles using natural gas per ISO 15403-1 (monofuel, bi‑fuel, dual‑fuel). The standard clarifies marking, construction, assembly and specific functional tests for CNG pressure indicators (gauges and transducers). It excludes LNG components upstream of the vaporizer, fuel containers, stationary gas engines, certain mounting hardware, electronic fuel-management and refuelling receptacles.

Key topics and technical requirements

• Scope & applicability
  • For CNG vehicular fuel systems; pressures are gauge pressures unless stated otherwise.
  • Based on a reference service pressure of 20 MPa (200 bar) at 15 °C; other service pressures scaled by ratio (e.g., 25 MPa ×1.25).
• Marking
  • Must include manufacturer/agent ID, model/part number, and working pressure or pressure/temperature range. Additional recommended markings include flow direction, fuel type and electrical ratings.
• Construction
  • Pressure indicators must display at least 1.5× service pressure.
  • Gauges require shatter‑proof lens and an external pressure-relief path not directed to the front.
• Mechanical and functional tests
  • Hydrostatic strength: test at 2.5× working pressure per ISO 15500-2 procedures.
  • Leakage: tested across specified temperatures and pressure conditions.
  • Continued operation: 20 000 cycles (pressurize to WP, depressurize to <0.5×WP) followed by leakage verification.
• Electrical tests (if applicable)
  • Insulation resistance: 1 000 V DC between connector pin and housing for ≥2 s; minimum 240 kΩ.
  • Minimum operating voltage: ≤8 V for 12 V systems and ≤16 V for 24 V systems; component pressurized at 0.75× WP during test and reading must meet manufacturer tolerance.

Applications - Who uses ISO 15500-8:2015

• CNG pressure indicator and transducer manufacturers (design, type approval, QA).
• Vehicle OEMs and system integrators specifying compliant CNG components.
• Test laboratories and certification bodies performing hydrostatic, leakage and electrical tests.
• Fleet operators and maintenance teams referencing safe component criteria for CNG vehicles.

Related standards

• ISO 15500 series (Parts 1–20) - CNG fuel system components
• ISO 15500-1 (general requirements) and ISO 15500-2 (test methods)
• ISO 3833 (vehicle types and definitions)
• ISO 15403-1 (natural gas quality for vehicle fuel)

Keywords: ISO 15500-8:2015, CNG pressure indicator, compressed natural gas, pressure gauge tests, hydrostatic strength, insulation resistance, vehicle CNG components.