Validation of a Zone Model for Predicting Smoke Obscuration in Rooms

Abstract

Fires in a room often start small with the ignition of a combusti ble item such as a waste paper basket. As the fire grows, a smoke layer develops at the ceiling level. The smoke, as it descends, obscures signs and egress routes thus making it difficult to escape from the fire-affected room. In this paper, a brief discussion is given on the measurement of smoke and the importance of various smoke measurement parameters and the differential equations for calculating the smoke obscurations in a room are presented. The predictions of the model are then compared with obscuration data available from room corner fire tests involving three type of wall lining materials. The comparisons are in reasonable agreements with the test data. Some loss of smoke information is observed for polystyrene foam material and this resulted in the model under predicting the smoke obscuration as compared to the fire test. This loss of infor mation is suspected to be due to deposition of the soot on the duct surfaces dur ing the transport process.