Overview
ISO 5657:1997 - "Reaction to fire tests - Ignitability of building products using a radiant heat source" specifies a laboratory method to assess the ignitability of essentially flat building products, composites or assemblies when exposed horizontally to a controlled radiant heat flux. The test is intended for comparative evaluation and quality control of materials and does not by itself predict full-scale fire behaviour.
Key topics and technical requirements
- Test principle: specimens are irradiated on the exposed surface at constant irradiance (typical range 10–70 kW/m²) while a pilot flame is applied periodically above the centre to detect ignition.
- Specimens: five specimens tested per irradiance level; nominal specimen size 165 mm × 165 mm; full thickness up to about 70 mm (thicker products are reduced to the required thickness).
- Ignition definitions: distinguishes sustained surface ignition (flame still present after next pilot application, >4 s) and transitory ignition (
