Smoke Component Yields from Bench-Scale Fire Tests

A standard procedure is needed for obtaining smoke toxic potency data for use in fire hazard and risk analyses. Room fire testing of finished products is impractical, directing attention to the use of apparatus that can obtain the needed data quickly and at affordable cost. This report examines the first of a series bench-scale fire tests to produce data on the yields of toxic products in both pre-flashover and post-flashover flaming fires. The apparatus is the radiant furnace in NFPA 269 and ASTM E 1678. Test specimens were cut from finished products that were also burned in room-scale tests: a sofa made of upholstered cushions on a steel frame, particleboard bookcases with a laminated finish, and household electric power cable. Initially, the standard test procedure was followed, with a variation to reduce the contribution to the effluent of post- flaming pyrolysis. Subsequent variations in the procedure included cutting the test specimen into small pieces and performing the tests at a reduced oxygen volume fraction of 0.17. The yields of CO2 CO, HCl, and HCN were determined. The yields of other toxicants (NO, NO2, formaldehyde, and acrolein) were below the detection limits, but volume fractions at the detection limits were shown to be of limited toxicological importance relative to the detected toxicants. In general, dicing the test specimen and performing the tests at the reduced oxygen volume fraction had little effect on the toxic gas yields, within the experimental uncertainties. The exceptions were an increase in the CO yield for diced specimens at reduced oxygen, a decrease in the HCN yield from the intact sofa and cable specimens at reduced oxygen, and an increase in the HCN yield from dicing the cable specimens. In none of the procedure variations did the CO yield approach the value of 0.2 found in real-scale post flashover fire tests.