ISO 15500-11:2015

Overview

ISO 15500-11:2015 is an international standard developed by the International Organization for Standardization (ISO) that specifies the tests and requirements for gas/air mixers used in compressed natural gas (CNG) fuel system components for road vehicles. This part of the ISO 15500 series focuses specifically on the gas/air mixer, an essential component in motor vehicles that use natural gas as a fuel source. The standard applies to vehicles as defined in ISO 3833 and is relevant for mono-fuel, bi-fuel, or dual-fuel vehicles complying with ISO 15403-1. It excludes components related to liquefied natural gas (LNG) fuel systems, fuel containers, and other specified hardware.

Key Topics

• Scope and Applicability
  The standard covers gas/air mixers intended for CNG systems operating at a typical service pressure of 20 MPa (200 bar) at 15 °C, with provisions to adjust for other service pressures. It applies only to CNG fuel systems and excludes LNG systems, refuelling receptacles, electronic fuel management, and stationary engines.

• Marking Requirements
  Components must be clearly marked with traceable information such as manufacturer identification, model designation, working pressure, temperature range, and optional details like flow direction, fuel type, and certification symbols.

• Construction and Assembly
  Gas/air mixers must conform to the construction guidelines outlined in the general parts of ISO 15500 (Parts 1 and 2), ensuring durability and compatibility with other fuel system components.

• Testing Protocols
  ISO 15500-11:2015 defines several critical tests to ensure safety and reliability:

  • Hydrostatic Strength Test: Verifies the component withstands pressures at 4 times the recommended working pressure or 600 kPa, whichever is higher.
  • Leakage Test: Conducted across temperature ranges from -40 °C to +120 °C, verifying the mixer’s sealing integrity at pressures above working pressure.
  • Continued Operation Test: For mixers with moving parts, a durability test involving 100,000 cycles simulates long-term operational wear.
  • Corrosion Resistance Test: Ensures that materials used can withstand environmental exposure and maintain functionality.

• Types of Gas/Air Mixers Covered
  The document accommodates three mixer designs: positive and negative pressure venturi mixers (no moving parts) and variable orifice mixers.

Applications

ISO 15500-11:2015 provides critical guidance for manufacturers, designers, and testing laboratories involved in the production and certification of gas/air mixers in CNG fuel systems for road vehicles. Its practical applications include:

• Assurance of Fuel System Safety
  By specifying stringent testing methods and construction criteria, the standard helps prevent leaks, failures, and malfunctions related to gas/air mixing in CNG vehicles.

• Compatibility and Interchangeability
  Uniform marking and performance requirements enable seamless integration of gas/air mixers with other CNG fuel system components, contributing to vehicle reliability.

• Support for Clean Energy Vehicles
  Facilitates the adoption of natural gas as a cleaner alternative fuel by ensuring components meet international safety and performance benchmarks.

• Regulatory Compliance and Certification
  Enables manufacturers to demonstrate conformity with globally recognized standards, aiding market acceptance and regulatory approvals.

Related Standards

• ISO 15500 Series
  ISO 15500 comprises a comprehensive set of parts covering CNG fuel system components such as valves, injectors, regulators, and fuel lines. Part 11 complements these by focusing on gas/air mixers.

• ISO 3833
  Defines types of motor vehicles and relevant terminology for consistent classification.

• ISO 15403-1
  Specifies the quality and composition requirements for natural gas used as a compressed fuel, ensuring fuel consistency in accordance with which this standard applies.

• ISO 15500-1 and ISO 15500-2
  Provide general requirements, definitions, and performance test methods for CNG fuel system components, forming the foundation for Part 11 requirements.

Keywords: ISO 15500-11:2015, gas/air mixer, compressed natural gas (CNG), fuel system components, CNG vehicle standards, natural gas fuel system, automotive CNG components, gas/air mixer testing, CNG safety standards, natural gas vehicle regulations.