ISO 5164:2014

Overview

ISO 5164:2014 specifies the research method for determining the knock characteristics of motor fuels by assigning a Research Octane Number (RON). The method uses a standard single‑cylinder, four‑stroke, variable‑compression‑ratio, carburetted CFR engine (CFR F‑1 Octane Rating Unit) operated at constant speed. ISO 5164:2014 covers the full octane scale from 0 RON to 120 RON (working range 40–120 RON), with typical motor fuel testing in the 88–101 RON range. The standard is applicable to oxygenate‑containing fuels up to 4.0 % (m/m) oxygen and gasolines containing up to 25 % (V/V) ethanol.

Key Topics

• Test principle - rating fuels on an arbitrary octane scale using a CFR engine to measure knock under mild operating conditions.
• Apparatus and instrumentation - detailed requirements for the CFR engine, knock/detonation meter (analogue and XCP digital systems are allowed), carburettor and ancillary equipment.
• Engine settings and environmental control - mandatory settings and limits (engine speed, valve timing and lift, intake air temperature/humidity, coolant and oil temperatures, spark settings, fuel–air ratio).
• Sampling and sample preparation - guidance for representative sampling and handling of motor fuel samples.
• Calibration, qualification and procedure - engine fit‑for‑use tests, calibration with primary reference fuels, step‑by‑step test procedure and special instructions for ratings above 100 RON.
• Calculation and expression of results - how to derive RON values and report them.
• Precision and uncertainty - repeatability and reproducibility data, including provisions for fuels with high ethanol content.
• Test reporting - required information and documentation for conformity and traceability.

Applications

• Quality control and acceptance testing of automotive gasoline and gasoline blends.
• Research and development of new fuel formulations and octane rating optimization.
• Regulatory compliance and fuel specification verification for refineries and fuel distributors.
• Engine calibration and knock mitigation studies for OEMs and testing laboratories.
• Comparative studies of ethanol‑blended fuels and oxygenated gasoline performance.

Who should use this standard

• Accredited fuel testing laboratories and petrochemical quality control teams.
• Refiners and fuel marketers developing or verifying gasoline grades.
• Automotive OEMs and engine research groups assessing fuel knock characteristics.
• Regulatory bodies and standards organizations setting fuel specifications.

Related Standards

• ISO 5164:2014 formally adopts procedures aligned with ASTM D2699 (the ASTM CFR research octane test method) and refers to its annexes and appendices for detailed equipment and operational tables. ISO/TC 28 (Petroleum products and lubricants) is the responsible committee.

Keywords: ISO 5164, research octane number, RON, knock characteristics, CFR engine, motor fuel testing, octane rating, petroleum standards.