Overview
EN ISO 9038:2025 - Determination of sustained combustibility of liquids specifies a laboratory procedure to determine whether a liquid that is classified as flammable by its flash point will sustain combustion at specified test temperatures (up to 100 °C). The method is intended as a follow-up to flash-point testing: it does not measure flash point but assesses whether a product continues to burn after an ignition source is removed. The standard was prepared by ISO/TC 28 in collaboration with CEN/TC 139 and is published as an EN standard.
Key topics and technical requirements
- Scope and applicability: Applicable to paints (including water-borne), varnishes, paint binders, solvents, petroleum and related products, and adhesives that have a flash point. Not applicable to painted surfaces.
- Definition of sustained combustibility: Vapour ignites and burning continues for at least 15 seconds after removal of the ignition source.
- Test temperatures: The method covers tests up to 100 °C. Regulatory reference temperatures commonly used include 60.5 °C and 75.0 °C (aligned with UN Transport of Dangerous Goods and GHS derived regulations).
- Sample size and speed: The procedure enables rapid evaluation using a small test portion (typically 2 ml).
- Apparatus and control: Requires a combustibility tester and an electrical heater capable of maintaining cup temperature within ±0.5 °C in a draught-free area (see Annex A and B for apparatus and verification).
- Procedure elements: Includes sample preparation, controlled heating, application and removal of ignition source, observation criteria and result assessment. Warnings and operator safety guidance are provided for potential ignition scenarios.
- Reporting: Test report elements and calculation methods (including adjustment of test temperature) are specified.
Applications and who uses it
- Manufacturers and formulators of paints, varnishes, adhesives, solvents and petroleum products use EN ISO 9038:2025 to assess fire hazard beyond flash-point classification.
- Independent test laboratories performing regulatory compliance and product safety testing.
- Regulatory authorities and transport compliance specialists who evaluate derogations from flammability restrictions when sustained combustion is the deciding factor.
- Safety engineers and risk assessors who need evidence on whether a flammable liquid will continue to burn under specified storage or transport temperatures.
Related standards
- ISO 1513 - Paints and varnishes: sample exam/preparation
- ISO 3170 / ISO 3171 - Petroleum liquids sampling (manual/automatic)
- ISO 15528 - Paints, varnishes and raw materials sampling
- Flash point test methods (refer to recognized flash-point standards for initial classification)
EN ISO 9038:2025 is a practical, rapid test method for determining sustained combustibility and supporting fire-hazard assessments required by transport, storage and product-safety regulations.
