Overview
ISO 15500-19:2020 specifies tests and requirements for fittings used in compressed natural gas (CNG) vehicle fuel systems. It applies to CNG systems on motor vehicles defined in ISO 3833 (mono-fuel, bi-fuel and dual-fuel) using natural gas per the ISO 15403 series. The standard excludes LNG components upstream of the vaporizer, fuel containers, stationary engines, container-mounting hardware, electronic fuel management and refuelling receptacles.
Keywords: ISO 15500-19, CNG fittings, compressed natural gas fittings, vehicle fuel system components, CNG standard
Key topics and requirements
- Scope and applicability
- Targets fittings for CNG vehicle fuel systems; compatible with natural gas quality defined by ISO 15403.
- Marking
- Mandatory marking to allow traceability: manufacturer/agent name or symbol, model/part number, working pressure (or pressure‑temperature range), and serial number/date code.
- Recommended additional markings: flow direction, fuel type, electrical ratings, certification symbol, type approval number, reference to the standard.
- Construction and compatibility
- Fittings must meet ISO 15500-1 and ISO 15500-2 provisions.
- Rigid fuel line compatibility is required; stainless-steel lines must use stainless-steel fittings.
- Prevention of galvanic corrosion is mandatory.
- Performance tests
- Hydrostatic strength: tested per ISO 15500-2 at four times the working pressure.
- Continued operation: cycling test of 100 000 cycles while fitted to a rigid fuel line; followed by leakage and hydrostatic tests.
- Pull-off: fittings are tested attached to rigid line and mating parts; tensile load applied (max 250 N/min) until separation. The measured pull-off force must exceed a calculated threshold based on internal diameter and working pressure (the requirement already embeds a safety factor of 4).
- Repeated assembly: fittings must withstand 25 assembly/disassembly cycles representative of field use and still meet leakage requirements.
- Other referenced tests in ISO 15500-2 include leakage, excess torque, bending moment, corrosion and material ageing tests.
Applications and who uses it
- Fitting and component manufacturers designing CNG connectors, adapters and inline fittings.
- OEMs and vehicle integrators specifying compliant fuel-system components.
- Test laboratories and certification bodies performing hydrostatic, endurance and pull-off testing.
- Regulatory authorities and fleet managers ensuring safety and traceability for CNG vehicle installations.
Practical value: ensures mechanical integrity, leak resistance, material compatibility and traceability of CNG fittings in high‑pressure vehicle fuel systems.
Related standards
- ISO 15500-1 - General requirements and definitions (CNG components)
- ISO 15500-2 - Performance and general test methods (referenced test procedures)
- ISO 3833 - Road vehicle types, terms and definitions
- ISO 15403 series - Natural gas quality for vehicle fuels
For designers, manufacturers and test labs working on CNG fuel systems, ISO 15500-19 is the authoritative reference for fitting performance, marking and test criteria.
Open preview (PDF)Road vehicles — Compressed natural gas (CNG) fuel system components — Part 19: Fittings