Correct temperature measurements in fire exposed wood

Abstract

The performance of timber in fire is often assessed by measuring the temperature at different positions in the specimen. As timber is a low conductive material, it can be difficult to measure the correct temperature. Therefore, this paper shows how to correctly measure the temperature in timber members and how to describe temperature measurements of fire tests and experiments non-ambiguously. Typical temperature measurement setups used in tests and experiments were experimentally assessed under ISO/EN fire exposure and a constant incident radiant heat flux. By comparing the charring depth and the thermocouple readings (charring temperature 300°C) it was found that only the wire thermocouples inlaid parallel to the isotherms deliver correct temperature readings. For other temperature measurement setups, the underestimation was between 5 and 20 minutes. Due to the numerous factors influencing the measurement error, no correction factor could be defined.