Toxic species and particulate emissions from synthetic polymer fires

Abstract

Overall fire statistics and residential and industrial fires in which there have been large number of fatalities demonstrate that the cause of most deaths can be attributed to effects of toxic smoke produced in these fires. Despite this fact there are no national or international legal requirements to determine the toxic emissions from materials used in construction, electrical cabling or the wide range of polymer based products used in house construction and industry. Many polymers used commercially are fire retarded and the materials used for this can add to the toxicity. The only indirect control comes through some test requirements for product classification based on the volume of smoke production. However, this is not an adequate approach to the problem. Fire smoke contents can cause death directly or can impair escape so that people die indirectly from the effects of toxic gases, and in the first we need to identify and quantify these emissions for different materials and under different fire conditions. Currently, as a consequence of this lack of legal requirements, there is a dearth of data on toxic emissions from real industrial products under fire conditions. This research was focused on toxic gas emissions under fire conditions from practical industrial polymeric materials: insulating foams, electrical cables, Polyethylene and Polystyrene goods together with some other polymeric materials: rubber, GRP, PVC pipes and clear Acrylic. All were either used by industry who gave samples for testing or were on sale in construction product retailers. Some of the goods were fire retarded and had HCl, HBr or HF in the product gases or had high ash content. These generally produced higher toxic emissions than non-fire retarded products. Most of the work was carried out using the Leeds University modified Cone Calorimeter with raw gas sampling from a chimney above the cone outlet. A heated sample line, heated filter and heated sample pump with heated FTIR was the method of analysis used. All products were found to have significant toxic gas emissions, but the most important toxic gas depended on the material tested and was rarely CO. A data set of toxic emissions and toxic gas yields was produced which is greater than most data sources in the literature for synthetic polymer materials. Part of this work was the modification of the Purser Furnace by adding raw hot gas sampling and eliminating the backflow of dilution air into the reaction tube. This took a long time to design and construct and was only available at the end of the research work where it was used with PE samples at lean and rich equivalence ratios. A significant part of the work was the first use of this equipment for particle size analysis using the DMS 500 instrument. Ultra fine particles (<50nm) were present in all the fires and were a significant health hazard.