Adiabatic surface temperature and the plate thermometer for calculating heat transfer and controlling fire resistance furnaces

Abstract

The concept of adiabatic surface temperature AST can be used to express fire exposure or insult on a structure. Thus it has been used to facilitate data transfer from the FDS computer fire model to finite element models for calculating temperature in fire exposed structures. It is also shown that the Plate Thermometer as specified in the international fire resistance test standards ISO 834 and EN 1363-1 for harmonizing fire resistance testing approximately measures adiabatic surface temperature. Therefore furnace temperature as measured with the PTs can be used directly to calculate the heat transfer to a specimen and thereby its temperature. The definition and applications of the concept of AST is described in this paper including an analogy with electric current and voltage to illustrate the concept in a graphical format. Finally it is recommended that PTs are introduced in all fire resistance standards as it harmonizes fire resistance testing as well as it provides reliable data for numerical predictions of heat transfer to fire exposed structures. Copyright © 2008 International Association For Fire Safety Science.