Development of an improved radiant heat source for fire testing

The development, construction, and testing of a gas‐fired radiant heat source for use as part of a fire test method is described. The unit has been shown capable of operation over extended periods at surface temperatures yielding radiance corresponding to that of a black body at 935 °C. This permits a 60% increase of specimen irradiance over that possible with a burner previously used, without modifying the specimen–burner configuration factor. One such application of this burner allows operation with specimen irradiance levels at 5 W cm −2 or for short periods at levels approaching 7 W cm −2 at higher temperatures. This performance is achieved while maintaining effective spatial separation between specimen and heat source. This assists in avoiding imposition of vitiated air near the surface of a burning specimen. Some performance data are provided on its behavior when supplied with natural gas. The unit can burn propane but only with a significant reduction of thermal output.