NCJ Number
72892
Journal
Fire and Arson Investigator Volume: 30 Issue: 4 Dated: (April-June 1980) Pages: 42-46
Date Published
1980
Length
5 pages
Annotation
A method for determining the point of a fire's origin is described in this article.
Abstract
Using this method, the investigator begins by eliminating those areas where the fire could not have started. Products of combustion will rise until they encounter an obstruction to their vertical travel and then move horizontally until they reach another vertical opening. In a building of several floors, smoke discoloration of the walls will be closest to the ceiling on those floors highest above the point of origin. On floors closer to the origin, but still above it, smoke discoloration will appear further down the walls. In the room where the fire originated, smoke and charring will appear almost at the floor level. The products of combustion were produced faster than they could escape from the room, and the entire area became charged with smoke and heat. The radiant heat from the original fire will have extended outward and up, and thus objects in the room will show charring damage at a level equal to the lowest point of the flame in the early stages of the fire. The rising smoke and gas will have fanned out, causing what has been referred to as the rising cone effect in the room. The apex of the cone of damage will point to the general area of the origin of the fire. Rooms that have been extensively damaged by extremely hot fires may show severe charring damage to the floor. This charring will be uniform across the entire floor, and it may have been caused by heat re-radiated down from the ceiling or by falling hot embers. In cases involving the collapse of large, one-story, light industrial occupancy buildings, the scene should be examined from above to determine the area of severest fire damage and where search efforts should begin. References are not included.