Analysis of work on smoke component yields from room-scale fire tests

Abstract

Smoke Component Yields from Room-Scale Fire Tests (NIST Technical Note TN 1453) has recently been published. This was expected to be an important work in developing concentrations and yields of toxicants that could be used for evaluating the usefulness of small scale smoke toxicity apparatuses (or fire models) for use in the prediction of the toxicity of materials and products in real fires. However, the work has a number of uncertainties that limit its potential for use as a reference. There are three major problems with this work. First, the post-flashover concentrations of CO are too low (as recognized by the authors who recommend that this part of the data not be used). Second, the post-flashover concentrations of the main toxicants measured (HCN and HCl) were much higher than found in most studies. Third, the precision of the data was inadequate. The consequence of the first two issues is that the work seriously overestimates the toxicological importance of gases known to have only minor effects in post-flashover fires, such as HCN and HCl. The very low concentrations of toxicants measured at pre-flashover conditions might have a value not discussed by the authors: an indication that pre-flashover fires of the type conducted here do not generate extremely toxic atmospheres. Accordingly, the report does not provide reliable characteristic room scale combustion gas data that can be used for validating small-scale furnaces.