ISO 12614-18:2021

Overview

ISO 12614-18:2021 specifies tests and requirements for the gas temperature sensor used as a component of liquefied natural gas (LNG) fuel systems on road vehicles (types defined in ISO 3833). The standard defines construction, marking, mounting location and functional tests to ensure safe, reliable temperature sensing in LNG vaporizer and fuel delivery systems. It excludes fuel containers, stationary gas engines, container mounting hardware, electronic fuel management and refuelling receptacles.

Key topics and technical requirements

• Scope & pressure basis: Requirements reference a working pressure of 1.6 MPa (16 bar); other pressures are accommodated by a pressure-ratio factor (e.g., 2.0 MPa → multiply pressures by 1.25). All pressures are gauge pressures unless noted.
• Marking: Sensor marking must allow traceability - manufacturer, model/part number, working pressure or pressure/temperature range, and serial number/date code. Optional markings include flow direction, fuel type, electrical ratings and certification symbols.
• Mounting & operation:
  • Installed on the outlet pipeline of the LNG vaporizer and before or on the automatic shut-off valve or valve body.
  • Temperature set point is the vehicle manufacturer’s responsibility but must not be lower than −40 °C.
  • Sensor can be a contact switch and may interface to the ECU; it may be temporarily inactive after engine start to allow warm-up.
• Mandatory tests (selected):
  • Hydrostatic strength: test pressure = 2.5 × working pressure, per ISO 12614-2 procedures.
  • Leakage: tests at specified temperature/pressure combinations (see standard table).
  • Insulation resistance: apply 500 V d.c. for 60 s (or 100 V d.c. for circuitry with ≤3.8 mm pitch). Minimum resistance 240 kΩ.
  • Minimum operating voltage: device must operate at 9 V for 12 V systems and 18 V for 24 V systems (room temperature).

Applications

• Use ISO 12614-18:2021 to design, test and validate LNG gas temperature sensors for buses, trucks and other LNG-fueled road vehicles.
• Supports component manufacturers, OEMs, test laboratories and certification bodies in ensuring sensor safety, pressure integrity, electrical insulation and functional performance.
• Useful for quality assurance, type approval and supplier specification when integrating temperature sensors into LNG fuel systems.

Related standards

• ISO 12614-1 - General requirements and definitions for LNG fuel system components
• ISO 12614-2 - Performance and general test methods (referenced for test procedures)
• ISO 3833 - Vehicle types, terms and definitions

Keywords: ISO 12614-18:2021, gas temperature sensor, LNG fuel system components, LNG sensor testing, hydrostatic strength, insulation resistance, LNG vehicle standards.