Experimental Study on the Smouldering Combustion of Mineral Wool Insulation in Chimney Penetrations

Abstract

A large number of fires have been caused by metal chimney penetrations in recent years. One factor that has contributed to these occurrences is smouldering combustion within mineral wool, which is often used as insulation in metal chimneys and their penetrations. Based on reaction to fire performance mineral wool is typically classified as a non-combustible material and in European standards it belongs to category Euroclass A1. However, mineral wool insulation products contain organic material, which smoulders and generates heat at temperatures between 200°C and 500°C. Experimental research indicates that this additional heat may increase the temperature in the chimney penetration materials over 100°C for a limited period of time. The European fire classification of materials does not set requirements to control mineral wool smouldering and limit the subsequent heat release. This experimental study examined the smouldering of mineral wool insulation products specified for chimney penetrations and the heat release generated during the smouldering combustion. The aim of the study was to determine the actual level of temperature increase within the chimney penetration and to estimate the effects of the increase with regard to fire safety. The study also reviewed how the smouldering potential of an insulation material could be considered in the fire classification of products.