ISO 12614-3:2021

Overview

ISO 12614-3:2021 - Road vehicles - Liquefied natural gas (LNG) fuel system components - Part 3: Check valve specifies tests and requirements for check valves used in LNG fuel systems for road vehicles (as defined in ISO 3833). The standard defines marking, construction/assembly expectations and the specific functional tests (hydrostatic strength, leakage, continued operation) required to verify safe, reliable check valve performance for LNG applications. All pressures are gauge pressures and the document is based on a nominal working pressure (WP) of 1.6 MPa (16 bar); other WPs are accommodated by applying a ratio (for example, 2.0 MPa requires a 1.25 multiplier).

Key Topics and Requirements

• Marking and traceability
  • Mandatory: manufacturer name/trademark, model/part number, working pressure or pressure–temperature range, serial number or date code.
  • Recommended: flow direction, fuel type, electrical ratings (if applicable), certification symbol, type approval number, reference to ISO 12614-3.
• Construction and assembly
  • Check valves must meet the general requirements of ISO 12614-1 and test methods of ISO 12614-2.
• Test program (applicability)
  • Test types referenced from ISO 12614-2 include hydrostatic strength, leakage, continued operation, corrosion resistance, vibration, brass compatibility, non‑metallic immersion and others; some tests (e.g., electrical over-voltages) are not applicable for many check valves.
• Hydrostatic strength
  • Test pressure = 2.5 × working pressure (WP).
• Leakage
  • Leakage tests are specified at multiple temperatures and pressure factors (see standard Table 2): e.g., at <−162 °C use 1.0 × WP and 0.25 × WP; at 20 °C use 0.25 × WP and 1.5 × WP; at 85 or 120 °C use 0.25 × WP.
• Continued operation
  • Check valves must withstand 7,000 cycles under a specified pressure cycling procedure (inlet at 1.25 × WP, venting to 0–0.5 × test pressure between cycles). Valve must function and pass the hydrostatic test afterwards.

Applications and Who Uses It

• Primary users
  • Vehicle OEMs, LNG fuel system designers, component manufacturers, test laboratories, certification bodies, fleet operators and procurement specialists.
• Practical uses
  • Design validation, production quality control, type approval and certification, supplier qualification, and contract/specification writing for LNG check valves in road vehicles.

Related Standards

• ISO 12614-1 - General requirements and definitions for LNG fuel system components
• ISO 12614-2 - Performance and general test methods for LNG fuel system components
• ISO 3833 - Road vehicles - Types - Terms and definitions

Keywords: ISO 12614-3:2021, LNG check valve, liquefied natural gas fuel system, check valve testing, hydrostatic strength, leakage test, continued operation, road vehicles.