ISO 15500-14:2020

Overview

ISO 15500-14:2020 outlines the requirements and test procedures for excess flow valves, a critical safety component in compressed natural gas (CNG) fuel systems for road vehicles. Developed by the International Organization for Standardization (ISO), this standard applies to mono-fuel, bi-fuel, and dual-fuel vehicles that utilize natural gas according to the ISO 15403 series. It specifies definitions, construction, marking, and the comprehensive testing methods necessary to ensure reliable performance and safety of excess flow valves installed in CNG systems as defined in ISO 3833.

The standard does not apply to liquefied natural gas (LNG) components prior to the vaporizer, fuel containers, stationary engines, mounting hardware, electronic fuel management, or refueling receptacles.

Key Topics

• Scope and Definitions

  • Defines internal and external excess flow valves
  • Differentiates shut-off and flow-limiter valve types
  • Specifies parameters such as activation flow and marking requirements

• Construction and Assembly

  • Mandates compliance with general CNG component requirements (ISO 15500-1 & -2)
  • Prescribes identification markings including manufacturer, technical data, and approval references

• Testing Protocols

  • Hydrostatic Strength: Evaluates housing durability under high pressure
  • Leakage: Assesses gas tightness under varying pressures and temperatures
  • Torque and Bending: Tests resistance to installation stresses (external valves)
  • Operational Cycling: Ensures valve reliability after repeated use
  • Pressure Impulse: Simulates pressure surges to verify integrity
  • Additional environmental and compatibility tests per referenced standards

• Performance Requirements

  • Activation at manufacturer-specified flow or pressure differential
  • Continued effective operation after cycling and impulse exposure
  • Correct flow limiting or shut-off function during excess flow events

Applications

ISO 15500-14:2020 helps manufacturers, suppliers, and vehicle integrators ensure that excess flow valves used in CNG vehicle fuel systems maintain stringent safety and performance standards. Typical applications include:

• Automotive OEMs and Conversion Companies
  • Use the standard to select and test CNG safety components to comply with market and regulatory requirements.
• Component Manufacturers
  • Develop and certify excess flow valves meeting international standards to ensure compatibility and widespread acceptance.
• Inspection Bodies and Regulatory Agencies
  • Reference the standard to assess component conformity and approve vehicle fuel systems.

Practical benefits of compliance include:

• Enhanced vehicle safety through reliable shut-off or limitation of gas flow in the event of system breaches
• Traceability of components via standardized markings
• Facilitation of global market access for compliant products

Related Standards

Implementing ISO 15500-14:2020 is most effective when used alongside other relevant standards in the CNG and vehicle safety domain, such as:

• ISO 15500-1: Road vehicles - CNG fuel system components - General requirements and definitions
• ISO 15500-2: Road vehicles - CNG fuel system components - Performance and general test methods
• ISO 15403 Series: Natural gas fuel specifications for vehicles
• ISO 3833: Classification and terminology for road vehicle types

In summary, ISO 15500-14:2020 provides an essential framework for the reliable testing and application of excess flow valves in CNG-powered road vehicles. Adoption of this standard supports safety, traceability, and international harmonization of CNG vehicle components.