Figure 4. — Positioning of fuel beds and side aprons during test fire. 



Measurements 



Rate of Spread 



The rate at which fire spread through the fuel was measured visually. An aluminum 

 strip with marks at each half-foot interval lay alongside the treated bed. An observer, 

 with a remote switch, activated an event marker which was attached to a recorder being 

 used to record weight loss. The time required for the fire front to cover each half- 

 foot interval was measured and the average steady-state rate of spread between the 3- 

 and 7-foot mark calculated. 



Weight Loss Rate 



The weight of the treated fuel bed was monitored during the fire on a recorder 

 which had previously been calibrated for a full scale deflection of 4.4 pounds (2,000 

 grams). The weight loss at the 3- and 7-foot intervals was determined. The time 

 between these intervals was computed from the rate-of -spread event marks and then the 

 steady-state rate of weight loss was calculated. 



Residue 



The fuel was allowed to burn until glowing combustion was completed; then the fuel 

 bed was weighed and the residue determined. 



Figure 5 shows a burning test in progress and the equipment being used for taking 

 the required measurements . 



8 



