Fire Safety Science Digital Archive

During the previous years, visible differences have been observed on the thermal response of a given specimen placed in standard furnaces piloted with thermocouples. The definition of a method for harmonizing the severity of the heat flux absorbed by a specimen in fire resistance furnaces is necessary in order to reduce the differences observed. For several years, the project of using plate thermometers instead of thermocouples to control the furnace temperature has been examined and discussed. These new sensors can be more appropriate than thermocouples to impose to the specimen a heat impact as they seem to be largely independent of the furnace characteristics. A new zone model has been developed to calculate the heat fluxes exchanged in the furnace and the temperature of the specimen, the furnace being controlled either by thermocouples or by plate thermometers. The model's equations bring more light on the reasons why the heat flux received by a plate thermometer is weakly dependent of construction parameters. The main features of this model are described. In order to present the capabilities and limits of the model, calculated results are compared to recent test results obtained on a reference specimen equipped with "calibration elements", and prediction results are given for some different specimens for which no tests have been executed, showing the advantages of plate thermometer control.