Surface parameters from small‐scale experiments used for measuring HCl transport and decay in fire atmospheres

Abstract

AbstractThe decay of HCl was investigated in two small‐scale scenarios: pure HCl injection into a 31 chamber and combustion of plasticized PVC in a 2001 chamber. The effects investigated included (1) humidity, (2) temperature, (3) concentration of HCl and (4) wall material. Surface materials studied were PMMA, ceiling tile (front and back), Marinite, painted PMMA, unpainted gypsum board and cement. In view of the very rapid HCl decay in most of those surfaces, the effects were often examined with small ‘chips’ of materials in a PMMA chamber, with fresh walls for each experiment. Experiments were also carried out to investigate the effect of surface ageing, with painted gypsum board, painted PMMA and unpainted gypsum board walls. HCl decay is very fast in cement or unpainted gypsum board surface (almost impossible to saturate with HCl) and almost as fast on ceiling tile and Marinite. Saturation of HCl can be reached on painted gypsum board and painted PMMA surfaces, albeit at different rates. An earlier empirical model from mathematical fitting had been followed by a new HCl generation, transport and decay model, with a sound physical basis. This allowed calculations of parameters for all the surfaces used. Much work has already been done in devising and writing a zone model for use together with fire hazard models (particularly the NIST model, FAST) to calculate correct HCL concentrations in various fire scenarios. This work, which concludes the investigation of these two static fire scenarios for the surfaces analysed, represents one more step in the pursuit of that goal.