ISO 15500-3:2020

Overview

ISO 15500-3:2020 - "Road vehicles - Compressed natural gas (CNG) fuel system components - Part 3: Check valve" specifies tests and requirements for check valves used in CNG vehicle fuel systems. It applies to mono-fuel, bi-fuel and dual-fuel road vehicles (as defined in ISO 3833) using natural gas in accordance with the ISO 15403 series. The standard defines marking, construction/assembly expectations and mandatory test regimes to ensure safe, reliable CNG check valve performance.

Key topics and technical requirements

• Scope and exclusions
  • Applies to CNG check valves for road vehicles; not applicable to LNG upstream components, fuel containers, stationary engines, container-mounting hardware, electronic fuel management or refuelling receptacles.
• Marking
  • Components must be traceable with: manufacturer/agent name or trademark, model/part number, working pressure (and temperature range), and serial number or date code. Recommended additional markings include flow direction, fuel type and certification marks.
• Construction and assembly
  • Check valves shall comply with general provisions in ISO 15500-1 and test methods in ISO 15500-2; tolerances should follow ISO 15500-2.
• Mandatory tests
  • Hydrostatic strength: tested at 2.5 × working pressure (WP) per ISO 15500-2 procedure.
  • Leakage: tested at specified temperatures and pressure factors (examples include cold tests at −40 °C or −20 °C, ambient and elevated temperatures with pressure factors relative to WP).
  • Continued operation: check valves must withstand 20 000 operational cycles and 240 hours of chatter flow. The test sequence includes applying six inlet pressure pulses at either 125% service pressure or 100% WP with the outlet closed, venting the outlet between cycles, and limiting outlet-side pressure to ≤ 0.5 × WP prior to the next cycle. After durability, leakage and hydrostatic tests are repeated.
  • Additional applicable tests (as per ISO 15500-2) include corrosion, ageing, vibration, compatibility and other mechanical tests where relevant.

Applications and users

• Manufacturers of CNG check valves and fuel-system components seeking product design and conformity criteria.
• Automotive OEMs integrating CNG systems into vehicles (mono-, bi- and dual-fuel platforms).
• Test laboratories performing certification, durability and safety testing for CNG components.
• Regulators, certification bodies and suppliers ensuring compliance with CNG fuel-system safety and performance requirements.

Related standards

• ISO 15500-1 - General requirements and definitions for CNG fuel system components
• ISO 15500-2:2016 - Performance and general test methods (referenced for procedures)
• ISO 15403 series - Natural gas quality for vehicle fuel
• ISO 3833 - Road vehicle types, terms and definitions

Keywords: ISO 15500-3:2020, CNG check valve, compressed natural gas, check valve testing, hydrostatic strength, leakage test, continued operation, CNG fuel system standard.