Overview
EN ISO 17507-1:2025 - Natural gas - Calculation of methane number of gaseous fuels for reciprocating internal combustion engines - Part 1: MNc method (ISO 17507-1:2025) defines the MNc method to calculate the methane number (MN) of gaseous fuels using the gas composition as the sole input. The standard applies to natural gas, biomethane, and their admixtures with hydrogen, and provides a repeatable calculation route to quantify fuel knock resistance for reciprocating internal combustion engines.
Key topics and requirements
- Scope and applicability: Method applies to natural gas and biomethane blends including hydrogen; users must verify that the gas composition falls within the standard’s valid range (Clause 5).
- Composition-only input: Calculation is performed solely from the measured gas composition-no engine testing input is required.
- MNc methodology: Components of the gas are grouped into predefined ternary and binary systems whose methane numbers were experimentally determined. The overall MN is derived by subdividing the mixture and applying optimization algorithms to combine partial-mixture results.
- Handling uncommon components: Clause 5 addresses treatment of gas components outside standard ranges or uncommon species.
- Expression of results: Defines how to report methane number values, including notation and significant figures.
- Uncertainty and bias: The standard includes principles for estimating uncertainty error and bias (Clause 5.5 and Annex C).
- Worked examples and validation: Multiple example calculations (Clause 6) and Annex A provide numerical results for software validation. Annex B offers user tools; Annex E explains the MNc method basis.
Applications and users
EN ISO 17507-1:2025 is intended for organizations that need a standardized, composition-based assessment of gaseous fuel knock propensity:
- Engine manufacturers specifying allowable fuels and warranty conditions.
- Gas suppliers and shippers assessing fuel compatibility with customer engines.
- Testing and calibration laboratories implementing software or tools to compute methane numbers.
- System integrators and fleet operators managing gas-engine installations.
- Regulators and standards bodies defining fuel quality requirements.
Practical uses include fuel acceptance checks, blend optimisation (including hydrogen blends and biomethane), engine match assessment, and software validation for methane-number calculators.
Related standards
Keywords: EN ISO 17507-1:2025, methane number, MNc method, natural gas, biomethane, hydrogen admixtures, knock resistance, reciprocating internal combustion engines, gas composition.