Tests of resistance to fire, representing fully developed fires, use more and more often heat flux gauges. In reaction to fire testing the initial stages of the fire are considered, ranging from smouldering cigarettes to small flames and "Single Burning Items". To characterise the thermal load to the test specimen, all national and international test methods need a direct measurement of the heat flux incident on the specimen.
Therefore the heat flux measurement is a crucial part of product quality assessment and enhancement, and must be performed accurately and according to metrological rules.
This project shows that the best way to solve the problems of heat flux meter calibration and utilisation is to establish a well-defined calibration chain and to standardise the use the HFM in fire tests.
European primary calibration facilities are now available in France and Sweden (LNE, SP). These means contribute to a well-defined secondary calibration facility for use at each of the laboratories where heat flux meters are used on a daily basis.
The secondary calibration units can be set in National Metrological Labs working for fire labs and other industries. Fire labs such as TNO in the Netherlands and VTT in Finland have participated to the building and the characterisation of these calibration chains.
Finally, Guidelines for fire testing laboratory users and Input for standardisation are proposed and discussed.