An Experimental Study on the Effect of Design Flue Gas Temperature on the Fire Safety of Chimneys

Abstract

Recently, numerous fires have started in Finland around roof penetrations of metal chimneys. One reason for the fires is the high flue gas temperatures of fireplaces. EN standards do not determine the flue gas temperatures of fireplaces meant for the spec- ification of temperature classes of chimneys. At present, the design of chimneys is based on the temperature indicated in the CE marking of fireplaces. The temperature indicated in the CE marking is the mean temperature of the nominal test. In order to investigate how representative and safe this mean temperature is, tests on different fireplaces were conducted. Flue gas temperatures of the fireplaces were measured during a nominal test, a safety test and extra heating. Even in the nominal test, the highest flue gas temperature was 37 Ct o 212C higher than the mean temperature. The highest flue gas temperature in the safety tests was about 120 Ct o 380C higher than the mean temperature indicated in the CE marking. During the extra heating test, the highest flue gas temperature was 160 Ct o 350C higher than that indicated in the CE marking. Due to the present method of determining flue gas temperatures, chimneys may be tested at a too low temperature.