NF P92-501 Thermal Radiation Flame Dripping Propagation Tester The thermal radiation flame spread tester is designed to evaluate the performance of rigid and flexible materials with a thickness exceeding 5 mm, in accordance with the French standard NF P92-501 for fire-retardant testing of building materials and railway rolling stock. The test principle involves subjecting the specimen to thermal radiation at an intensity of 30 kW/m², which may cause the release of combustible