Method of measuring the temperature of wood exposed to fire with type K thermocouples

The study of wood behaviour in the event of fire is of increasing interest in the civil engineering field. Wood is one of the most prevalent combustible materials used in buildings. However, this material is protected by the char layer during fire exposure. It can slow down the charring rate of timber in fire and protect the internal wood structure. In fire tests, it is very important to use the most effective method of measuring the temperature of wood. In this paper, experimental tests are performed in furnaces and the charring rate is determined by measuring the depth of the charred part of timber at the end of the time. This approach is compared to direct measurements given by thermocouples positioned at different depths in the wood sample in different directions (radial, longitudinal, and tangential). All test samples were tested in a furnace where three surfaces of the sample were exposed to ISO-834 fire standards. The comparison between the two methods of measuring the charring rate allowed us to evaluate the accuracy of the thermocouple measurements according to the implementation adopted in the sample. Besides, the factors affecting the temperature measurement results are also mentioned in this study such as the position of the thermocouple in the wood, the size of the measuring sample and the size of the thermocouple.