Methodology for Estimating Pyrolysis Rates of Charring Insulation Materials using Experimental Temperature Measurements

This paper presents the application of a simplified method to estimate pyrolysis rates from rigid closed-cell cellular plastics by means of experimental temperature measurements. These materials are extremely effective in meeting energy efficiency goals in buildings and their safe use should also be enabled and optimised by undertaking comprehensive fire safety analyses. The proposed methodology consists of determining the mass loss as a function of the thermal evolution by applying a mass conversion directly using thermogravimetric data under non-oxidative conditions. In order to verify this simplified method, an experimental programme based on 100 mm thick samples of rigid polyisocyanurate foam was conducted using a Cone Calorimeter, obtaining measurements of mass loss and temperature within the core of the material. A Monel plate was used on top of the sample in order to represent a simpler boundary condition by eliminating the smouldering process of the charred material. Although the pyrolysis rates using this methodology did not provide a perfect fit with experimental data, they showed similar trends, with a slightly delayed prediction but still accurate magnitude. This methodology presents potential for fire safety engineering applications in two domains: (1) as a complementary technique to improve the interpretation of results from standard and ad-hoc testing, and (2) as a design technique for the evaluation of potential heat release contribution and gaseous emissions of assemblies incorporating insulation materials.