AbstractA limited review of the methods available for measuring smoke from burning materials has been carried out in order to define a method that could provide data for calculating smoke load. Results available in the literature have been expressed on a common basis and augmented by further experimental work carried out with a furnace similar to the National Bureau of Standards test furnace and a smoke‐containment volume (13.4m3) closer to that used by the Fire Research Station test. Encouraging agreement between the data have been found for methods which allow smoke to become diluted and to accumulate. Agreement could be improved if an allowance was made for flaming being extinguished at different times in a test, dependent on thermal stress and oxygen concentration, even when a pilot light is present. To help express the results clearly, a new unit for smokiness is proposed—the obscura (ob) defined as 1 ob=1 dB light attenuation per metre of light path. The smoke‐producing potential of different materials (Do) is then expressed in units of obscura—cubic metres per gram of volatiles produced during the fire condition (ob
展开▼
