Burning Procedures 



The cribs were burned on a table placed on 

 a weighing system similar to that described by 

 George and Blakely 6 (fig. 2). Two methods 

 were used to control temperature buildup 

 around the load cells. A layer of Zonolite in- 

 sulation 3 inches (7.6 cm.) deep was placed 

 between the fuel and the weighing system. 

 This material was found to be thermally 

 stable up to 1,500°C. (2,700°F.); it is not 

 hygroscopic. Streams of compressed air were 

 continuously directed around the load cells 

 during the tests as a further safeguard against 

 temperature changes that could cause elec- 

 tronic drift. 



The procedure for burning began by condi- 

 tioning the combustion chamber to a temper- 

 ature of 90° F. (32.2° C.) and a relative hu- 

 midity of 20 percent. A slight positive pres- 

 sure was maintained to insure removal of all 

 of the effluent through the stack. The in- 

 duced convection had no measurable effect 

 on the burning characteristics of the fires. The 

 test cribs, including the 4 by 4's, were placed 

 on the weighing system and ignited at time 

 zero using 100 ml. of a 50:50 mixture of 

 ethanol and acetone contained in two trays. 

 During the following 60 minutes, weight loss 

 and radiant flux from the flame zone were 

 continuously recorded and flame heights were 

 photographed at 1-minute intervals. A Gier 

 and Dunkle directional radiometer with a 



15° -view angle placed 20 feet (6.1 m.) from 

 the fire was used to measure radiant flux. 



After the fire went out, the residues from 

 the 4 by 4's and the cribs were collected and 

 the dry weight calculated. 



Figure 2. — A schematic representation of the 

 combustion facilities. (Note: not drawn to 

 scale.) 



Particulate Sampling 



The particulate sampling system consisted 

 of a Neucleonic Corporation of America 

 Model HAS 69 high volume sampler and Gel- 

 men type A glass filter paper. The sampler 

 was connected to a piece of pipe 4 inches (10 

 cm.) in diameter; this was placed (as shown at 

 top of figure 2) in the center of the effluent 

 stack approximately 50 feet above the fire. 

 The end of the pipe was sealed and four holes 



6 Charles W. George and Aylmer D. Blakely. 

 Energy release rates in fire retardanl evaluation. Fire 

 Technol. 6: 203-210, illus. 1970. 



were drilled on the underside. The holes de- 

 creased in size from the center of the stack 

 outward so that the effluent cross section 

 could be sampled equally. 



The flow rate through the sampler was 

 found to be temperature dependent. There- 

 fore, gas temperature was measured and re- 

 corded at the sampler during a run. Calibra- 

 tion curves were used to obtain actual flow 

 rate. The flow rate up the stack was deter- 

 mined using a United Sensor and Control Cor- 

 poration Model PAE-36-M-W pitostatic probe 



5 



