ISO 12614-8:2021

Overview - ISO 12614-8:2021 (Excess flow valve for LNG vehicles)

ISO 12614-8:2021 specifies tests and requirements for the excess flow valve used in liquefied natural gas (LNG) fuel systems for road vehicles (types defined in ISO 3833). It is part of the ISO 12614 series covering LNG fuel system components and applies to mono‑fuel, bi‑fuel, and dual‑fuel vehicles that use natural gas in accordance with ISO 15403-1. The document defines design classes, marking, construction conformity with ISO 12614‑1 and ISO 12614‑2, and the functional and environmental tests required to verify safety and performance.

Key topics and technical requirements

• Valve types covered
  • Internal (installed inside cylinder/cylinder valve) and external excess flow valves
  • Shut‑off (stops flow) and flow‑limiter (limits flow; auto‑resets) designs
• Marking and traceability
  • Must include manufacturer/agent, model/part number, operating specs (working pressure, temperature range, valve type, activation flow or ΔP, maximum flow when activated), and flow direction where needed.
• Pressure basis
  • All pressures are gauge pressures. The standard is based on a nominal working pressure of 1.6 MPa (16 bar); other working pressures are accommodated by proportional scaling (e.g., 2.0 MPa → multiply pressures by 1.25).
• Mandatory tests
  • Hydrostatic strength - test at 2.5 × working pressure (per ISO 12614‑2 procedure)
  • Leakage - for shut‑off valves; internal leakage limit stated in the standard (see document)
  • Continued operation - cycle 20 times at working differential pressure, then re‑test leakage and hydrostatic strength
  • Operation - verify activation flow and minimum activation pressure using manufacturer’s conditions; flows corrected to 15 °C
  • Tests specific to external valves: excess torque resistance and bending moment
• Environmental and material tests
  • Corrosion, vibration, ageing, electrical overvoltage and material compatibility tests referenced in ISO 12614‑2 as applicable

Applications and users

ISO 12614-8 is intended for:

• LNG fuel system manufacturers and component suppliers designing excess flow valves
• Vehicle OEMs and integrators specifying certified components for LNG vehicles
• Testing laboratories and conformity assessment bodies performing performance and safety testing
• Regulators and certification agencies assessing compliance with LNG vehicle safety requirements

Practical benefits include improved safety in refuelling and crash scenarios, consistent product marking and traceability, and a clear test regime for verifying valve integrity under pressure and environmental stress.

Related standards

• ISO 12614-1 - General requirements and definitions (LNG fuel system components)
• ISO 12614-2 - Performance and general test methods
• ISO 3833 - Road vehicle types - terms and definitions
• ISO 15403-1 - Natural gas quality for vehicle fuels

Keywords: ISO 12614-8:2021, excess flow valve, LNG fuel system, liquefied natural gas, road vehicles, hydrostatic strength, leakage test, activation flow, working pressure.