Overview
EN ISO 15403-1:2008 (ISO 15403-1:2006) defines the designation of quality for natural gas used as a compressed fuel for vehicles (CNG). The standard provides manufacturers, vehicle and fuelling-station operators, and other stakeholders with the information needed to develop and operate compressed-natural-gas vehicle (NGV) equipment successfully. Fuel that meets this standard aims to ensure safe vehicle operation, protect fuel systems from corrosion, poisoning and deposits, and deliver satisfactory performance across climates and driving demands. Some provisions may also apply to natural gas in stationary combustion engines.
Key Topics
EN ISO 15403-1 covers the technical attributes and quality descriptors relevant to CNG, including:
- Gas composition requirements - defines the nature of natural gas (predominantly methane; methane mole fraction typically > 0.70) and acceptable levels of other hydrocarbons and inert components (e.g., ethane, propane, nitrogen, carbon dioxide). Typical calorific values range from about 30 MJ/m3 to 45 MJ/m3.
- Gas properties - parameters such as calorific value, density, relative density and Wobbe index (see ISO 6976 for calculation methods).
- Driveability and engine performance - guidance on parameters affecting combustion behaviour, knock resistance and performance (related concepts include methane number and octane number).
- Test methods and sampling - normative and recommended procedures for measuring composition, contaminants, water content and other properties to verify compliance.
- Protection against detrimental effects - requirements to avoid corrosion, poisoning, and liquid/solid deposition in fuel systems.
Informative annexes address topics such as propane and butane content, Wobbe index ranges, engine knock, methane number vs octane number, and water content of natural gas.
Applications
This standard is used by:
- Vehicle manufacturers and engine designers to specify fuel compatibility and design fuel systems for NGVs.
- Fleet operators and vehicle converters to select fuels that guarantee reliable operation and reduced maintenance.
- CNG fuelling station operators and gas suppliers to define and control delivered fuel quality and sampling/testing regimes.
- Regulators and standards bodies for aligning national CNG fuel quality requirements and safety practices.
- Operators of stationary combustion engines where some aspects of CNG quality designation are applicable.
Benefits include improved safety, longer equipment life, consistent engine performance and minimized downtime caused by fuel-related degradation.
Related Standards
- ISO/TR 15403-2 - Specification of the quality (technical report accompanying Part 1)
- ISO 6976 - Calculation of calorific values, density and Wobbe index from composition
- ISO 14532 - Terminology referenced within this standard
Keywords: EN ISO 15403-1:2008, ISO 15403-1:2006, compressed natural gas, CNG fuel quality, natural gas vehicles, NGV, Wobbe index, methane number, gas sampling, test methods.
