Overview
ISO 21266-2:2018 specifies standardized test methods to verify the minimum safety requirements for fuel systems that operate on compressed gaseous hydrogen (CGH2) and hydrogen/natural gas blends in road vehicles. Part 2 supports the safety criteria defined in ISO 21266‑1 and applies to complete vehicle fuel-system functionality as defined for motor vehicles (see ISO 3833). It is intended for OEMs, after‑market converters, test laboratories and regulatory or notified bodies responsible for vehicle approval.
Key Topics
- Cylinder mounting strength tests
- Inertia test: cylinders mounted to the vehicle (or representative body) are filled to at least 90% of capacity (gas density considered 0.2 kg/l); trolley deceleration is recorded (CFC 60) and maintained per ISO 21266‑1 for ≥30 ms.
- Static test: traction force applied to cylinder centre of gravity using the formula F = (M + 0.9 ρV) a, held and released per procedure.
- Alternative compliance: equivalent crash tests or validated calculations may be accepted.
- Acceptance: cylinders must remain attached and not interfere with seating.
- Leak test
- Performed after installation and at ambient temperature. System is filled upstream of the first-stage regulator at 1 MPa ± 0.1 MPa; connections are checked (gas detector, foaming liquid, or equivalent). Test repeated at service pressure ±1 MPa. Detected leaks must be relieved, repaired and re‑tested.
- Functional tests
- Main shut‑off valve must close when ignition is off, engine stalls, cranking occurs on another fuel, or the engine is not running on CGH2/blend.
- Receptacle clearance verification to conform with ISO 21266‑1.
- Receptacle mounting tests
- With the fuelling nozzle connected and system at service pressure, receptacle gas tightness must be maintained after a 670 N axial pull and a 200 N·m moment; followed by a leak check.
- Engineering guidance (Annex A)
- Practical recommendations for steel cylinder mountings: minimum attachment points, reinforcement plates, fastener classes and band dimensions.
Applications / Who Uses It
- Vehicle manufacturers and system integrators validating CGH2 and H2/CNG fuel systems.
- After‑market converters designing retrofit cylinder packs and mountings.
- Test laboratories and certification bodies executing standardized mechanical, leak and functional tests.
- Regulatory authorities and notified bodies reviewing type-approval evidence.
Related Standards
Keywords: ISO 21266-2:2018, CGH2, compressed gaseous hydrogen, hydrogen/natural gas blends, fuel system test methods, cylinder mounting, leak test, receptacle mounting, vehicle fuel safety.