ISO 15500-6:2020

Overview

ISO 15500-6:2020 is an international standard published by ISO that specifies the requirements and testing methods for automatic valves used in compressed natural gas (CNG) fuel systems on road vehicles. This standard targets CNG system components for vehicles defined under ISO 3833 and applies to mono-fuel, bi-fuel, or dual-fuel vehicles running on natural gas per the ISO 15403 series quality standards.

The scope of ISO 15500-6:2020 excludes liquefied natural gas (LNG) components upstream of vaporizers, fuel containers, stationary gas engines, mounting hardware, electronic fuel management systems, and refuelling receptacles. The standard ensures that automatic valves maintain safety, reliability, and performance under the high-pressure conditions typical of CNG fuel systems.

Key Topics

• Automatic Valve Definition
  An automatic valve is an on/off valve controlling gas flow without manual operation, essential for regulating CNG supply in vehicles.

• Marking Requirements
  Automatic valves must be clearly marked with manufacturer identity, model designation, working pressure and temperature ranges, serial or date codes, and where applicable, electrical ratings and certification marks. Special marking codes (H1, H2, H3) classify compatibility with various vehicle start-stop engine systems.

• Construction and Assembly
  Valves must comply with general ISO 15500-1 and 15500-2 requirements for construction and tolerance. The design mandates valves to be closed when de-energized, and valves with manual bypass must meet minimum performance criteria.

• Testing Procedures
  The standard prescribes rigorous testing including:

  • Hydrostatic strength at 2.5× working pressure to ensure valve integrity under extreme pressure.
  • Leakage testing across multiple temperatures and pressures simulating real-world conditions.
  • Continued operation testing for up to 1,000,000 cycles depending on start-stop engine compatibility.
  • Insulation resistance to verify electrical safety for valves with coil assemblies.
  • Minimum opening voltage thresholds aligned with vehicle electrical system voltages.
  • Pressure impulse tests to assess valve durability against sudden pressure surges.

These comprehensive tests guarantee automatic valves perform reliably and safely throughout their operational lifecycle in CNG fuel systems.

Applications

ISO 15500-6:2020 applies to automotive manufacturers, component suppliers, and testing laboratories involved in the development, production, and certification of CNG fuel system components. Typical applications include:

• Natural Gas Vehicles (NGVs)
  Vehicles using CNG as fuel, whether exclusively or in combination with conventional fuels, benefit from standardized automatic valves to ensure fuel flow control and safety compliance.

• CNG Fuel System Design and Manufacturing
  Component manufacturers use this standard to design valves that withstand high pressures, temperature variations, and operational stresses typical in transportation fuel systems.

• Quality Assurance and Certification Testing
  Testing bodies apply ISO 15500-6 protocols to verify valve performance and safety before market introduction or during vehicle maintenance cycles.

• Start-Stop Engine Systems
  The standard supports evolving vehicle technologies with automatic engine stopping features, ensuring valves remain dependable in new operational modes.

Related Standards

ISO 15500-6:2020 is part of the broader ISO 15500 series that governs CNG vehicle fuel system components. Related standards include:

• ISO 15500-1: General requirements and definitions for CNG fuel system components.
• ISO 15500-2: Performance and general test methods for CNG system components, providing foundational testing procedures referenced in Part 6.
• ISO 3833: Classification and terms for road vehicle types applicable to system scope definition.
• ISO 15403 Series: Specifications for natural gas quality used as vehicle fuel, ensuring component compatibility with fuel characteristics.
• IEC 60079-10-1: Explosive atmosphere classification related to intrinsic safety requirements for electrically operated components in potentially hazardous environments.

By aligning with these relevant standards, ISO 15500-6:2020 helps secure harmonized safety and functionality across CNG fuel systems in road vehicles worldwide.

Keywords: ISO 15500-6, automatic valve, CNG fuel system, compressed natural gas, vehicle fuel components, ISO 3833, natural gas vehicles, start-stop engine systems, hydrostatic strength test, leakage test, insulation resistance, pressure impulse test, CNG safety standards, fuel system certification.