Reproducibility and repeatability of furnace testing for fire resistance came one step closer last week as a result of a Workshop in Borås, Sweden. IFC's many clients who carry out fire resistance testing throughout the UK and the rest of the world are always amazed at the variety of test results that they achieve with fairly similar products. One of the main reasons for this is that the thermal dose differs furnace by furnace, laboratory by laboratory. The plate thermocouple introduced into the new EN fire resistance tests was an attempt to improve this situation, but perhaps carried with it a few other penalties, including an increase in the time constant which means that furnace heating in invariably faster. New devices have started to be considered by the International fire testing community, such as the differential flame thermometer. The Workshop on heat exchange in furnaces set out to review the current situation and make proposals for the future.
International Fire Consultants Ltd actively participated in the Workshop, recognising the importance of the subject to its many clients. Hans van de Weijgert gave an interesting paper looking at the heat exchange between the gases, the furnace refractory and the specimen. Peter Jackman, IFC's Technical Director, attended the Workshop in support of his ISO work where his Working Group has been looking at how to produce calibration specimens for fire resistance testing. The outcome of this Workshop was that in future the plate will be better specified and also probably modified in order to reduce its time constant and therefore make it more responsive.
Technical staff at IFC still have some concern about its directionality, particularly in some furnace specimen configurations and request that more work is undertaken to establish just how critical this parameter is.
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