Fire Pattern Repeatability: A Study in Uncertainty

Abstract The National Institute of Standards and Technology (NIST) is conducting a multi-year study, with the support of the National Institute of Justice (NIJ) and the NIST Office of Law Enforcement Standards (OLES), to examine the repeatability of fire patterns. The primary objective of the study is assessing the repeatability of fire patterns on gypsum board exposed to a limited range of source fires. The focus of this paper is an overview of the uncertainties of the measurements. The study required the use of a variety of measurements to determine the repeatability of the source fires in terms of heat release rate, temperature, heat flux, and flame height. Replicate source fire experiments were conducted in an oxygen consumption calorimeter in order to examine the repeatability of the fires in terms of the heat release rate. The flame movement and height for each fire were recorded with photographs and videos. The fire pattern experiments were conducted in a three-walled structure with a full floor and partial ceiling constructed from wood framing and lined with painted gypsum board. The source fires were positioned against the rear wall, midway along its length. Replicate experiments were conducted with each fuel. The fire patterns were documented and analyzed for repeatability. The fire pattern height results are then compared to the mean flame height results to examine the level of agreement.