Overview
ISO 12614-14:2021 specifies tests and performance requirements for the differential pressure fuel content gauge used in liquefied natural gas (LNG) fuel systems for road vehicles (as defined in ISO 3833). The standard focuses on the gauge as a component of LNG fuel systems and sets out marking, construction and test requirements to ensure safety, reliability and traceability in vehicle applications. It is one part of the ISO 12614 series covering LNG fuel system components.
Key topics and technical requirements
- Scope and applicability
- Applies to differential pressure fuel content gauges for motor vehicles; excludes fuel containers, stationary gas engines, mounting hardware, electronic fuel management and refuelling receptacles.
- All pressures are gauge pressures unless otherwise stated.
- Base working pressure: 1.6 MPa (16 bar); other system pressures are accommodated by applying proportional factors (e.g., 2.0 MPa × 1.25).
- Marking and traceability
- Required markings: manufacturer/agent identification, model designation, working pressure or pressure–temperature range, serial number or date code.
- Recommended markings include flow direction, fuel type, electrical ratings, certification symbol, approval number and reference to ISO 12614-14.
- Construction and assembly
- Pressure transducers and gauges must comply with ISO 12614-1 and ISO 12614-2 requirements.
- If the component is a gauge, it shall have a shatter-proof lens and a pressure relief means located at the rear of the body.
- Testing requirements
- Tests referenced from ISO 12614-2 are applicable; specific tests mandated here include:
- Hydrostatic strength: test pressure = 2.5 × working pressure.
- Leakage: performed at specified temperatures and pressure factors (see standard for table); tests include very low cryogenic temperatures (< −162 °C), ambient (20 °C) and elevated temperatures (85 °C or 120 °C) at defined pressure multipliers.
- Continued operation (durability): 20 000 cycles, where one cycle = pressurize to working pressure then depressurize to < 0.4 MPa (4 bar); followed by leakage test.
- Other applicable procedures include corrosion, vibration, excess torque, bending moment, electrical overvoltages and material compatibility tests as indicated in ISO 12614-2.
Applications and users
- Intended users:
- Automotive OEMs and Tier‑1 suppliers designing or integrating LNG fuel systems.
- Component manufacturers and test laboratories validating gauge performance to ISO 12614-14:2021.
- Certification bodies and regulatory authorities assessing component compliance.
- Practical applications:
- Ensuring accurate fuel content monitoring in LNG-powered road vehicles.
- Verifying mechanical and leak-tight integrity under cryogenic, ambient and elevated conditions.
- Providing traceability and safety features for vehicle installation and type approval.
Related standards
- ISO 12614-1 - General requirements and definitions for LNG fuel system components
- ISO 12614-2 - Performance and general test methods referenced throughout ISO 12614-14
- ISO 3833 - Road vehicles - Types - Terms and definitions
Keywords: ISO 12614-14:2021, differential pressure fuel content gauge, LNG fuel system components, LNG gauge testing, hydrostatic strength, leakage test, continued operation, road vehicles.