Internal Linings, the Interim Solution and a Simplified Classification System

In January 1990 an expert group was set up by DP2 of TC2, CEC to define the research and development work needed to be undertaken within the community to achieve a robust solution with respect to reaction-to-fire material classification. The expert group delivered in December 1990 its proposal for a 5-year research and development program. But a system of harmonised European fire test methods and classification system cannot await this period of development, so the search for an "interim solution" is on. The objective of this paper is to inform that very recent research (during the last year) at Lund University and other places has demonstrated that there exist simplified approaches, using the test developed within IS0 TC92/SCl, for an interim solution. In practical terms "the simplified approach" implies the following: the fire hazard assessment is made on the basis of a specified scenario (to bedenoted by scenario A), using DIS 9705 with a 100 kW ignition source and liningson walls and ceiling. Ignitability, and heat release rate (HRR) curves from DIS 5660 are directly used to calculate two indices dividing the products into 3 groups: 1. products where flame spread either does not start or immediately begins to decrease; 2. products where flame spread first accelerates but then stops; 3. products with experimentially increasing flamespread, generating room flashover. For group 3 materials, ignitability data and a direct, time weighted integral of the HRR-curve from DIS 5660 are combined into a simple algebraic expression or index, giving time to flashover tfo and providing a more detailed classification for that group of materials. Extensive validation studies have been carried out in the Nordic countries. The experience available from these studies strongly suggests that the whole procedure is simple, unambiguous and reliable. In addition, it complies with the requirements of fire engineering and is scientifically based. The same methodology has been applied to another scenario (to be denoted as scenario B): again DIS 9705 but with linings on three walls only. Again, indices giving time to flashover for those materials which cause room flashover or maximum value of heat released in the full-scale room test for material causing flashover are directly calculated from ignitability data and the KRR-curve generated by DIS 5660. The problem with scenario B as a basis for classification is that full-scale experimental validation is severely limitied (although validation by a 113 scale model of DIS 9705 is extensive). Underlying the calculation of the mentioned classification indices is a long term theoretical study of the fire growth process on internal linings and the development of various computer programs numerically simulating this process. This paper presents a summary review of these research activities and finishes by outlining explicitly the possible classification system