ISO 15500-9:2020

Overview - ISO 15500-9:2020 (CNG Pressure Regulator)

ISO 15500-9:2020 is the international standard that specifies tests and performance requirements for pressure regulators used in compressed natural gas (CNG) fuel systems for road vehicles (as defined in ISO 3833). It applies to mono‑fuel, bi‑fuel and dual‑fuel vehicle applications using natural gas in accordance with the ISO 15403 series. The standard defines marking, construction, and a comprehensive test program to ensure regulator safety and durability in vehicle service.

Key exclusions: LNG components upstream of and including the vaporizer, fuel containers, stationary gas engines, container‑mounting hardware, electronic fuel management and refuelling receptacles.

Key topics and technical requirements

• Marking and traceability: Manufacturer name/trademark, model/part number, working pressure and temperature range, maximum outlet pressure, and serial number/date code are required; additional identifiers (flow direction, electrical ratings, type approval) are recommended.
• Construction and assembly: Regulators must meet ISO 15500‑1 and ISO 15500‑2 provisions; downstream components must be protected from full upstream pressure (resetting pressure relief valve required).
• Hydrostatic strength: First‑stage inlet tested at 2.5× working pressure; downstream chambers tested at 2.5× relief valve set pressure (or upstream working pressure if no relief valve); multi‑stage outlet chambers/fittings tested at 2.5× working pressure or 0.4 MPa (4 bar), whichever is greater.
• External leakage: Leak tests across defined temperature and pressure ranges (including extreme cold and high temperature conditions).
• Continued operation (durability): Regulators must survive 50 000 cycles under specified temperature and pressure cycling without failure; lock‑up pressure must remain within manufacturer limits.
• Electrical tests (where applicable):
  • Insulation resistance: 1 000 V DC applied; minimum 240 kΩ.
  • Minimum opening voltage: ≤8 V for 12 V systems, ≤16 V for 24 V systems (other voltages tested at ≤66% nominal).
• Pressure impulse tests: Internal and external impulse tests to verify resistance to instantaneous pressure spikes (e.g., when filling an empty system).
• Water jacket freezing: Freeze/thaw conditioning to validate antifreeze/water jacket integrity and subsequent leak tightness.

Applications and users

This standard is essential for:

• CNG regulator manufacturers and component designers (design verification and type approval)
• Automotive OEMs integrating CNG systems into vehicles
• Test laboratories and conformity assessment bodies performing type testing
• Certification agencies and regulatory authorities setting vehicle fuel‑system safety requirements
• Fleet operators and maintenance engineers specifying compliant replacement parts

Related standards

• ISO 15500‑1: General requirements and definitions
• ISO 15500‑2: Performance and general test methods
• ISO 15403 series: Natural gas fuel quality
• ISO 3833: Road vehicle categories

Keywords: ISO 15500‑9, CNG pressure regulator, compressed natural gas regulator, CNG fuel system components, pressure regulator testing, hydrostatic strength, insulation resistance, pressure impulse.