| Abstract | A series of experiments at the National Fire Laboratory (NFL), measured the effects of water spray from automatic sprinklers on the temperature, pressure, oxygen, carbon dioxide and carbon monoxide levels in a building under fire conditions. The project was jointly funded by the American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE) and the National Research Council of Canada. Sprinklers act quickly to extinguish fires before they become large enough to create dangerous smoke conditions in a building. In these tests, however, particular attention was paid to shielded fires, in which an obstacle prevented water spray from extinguishing the burning fuel. In a office occupancy, for example, shielded fires could develop in combustible materials stored under a table or in a closet, or in compact mobile shelving units for paper filers. In shielded fires, sprinklers restrain the burning rate, prevent fire spread and reduce temperatures, but are not able to eliminate the smoke hazard in the building. Testing involved two phases. In the first phase, wood cribs were burned in a one-storey test room 6 m x 6 m x 3.6 m high. The second phase involved creating wood crib fires on the seventh floor of the NFL's ten-storey experimental tower; the fire floor was mechanically exhausted, while air was supplied lo pressurized the floors above and below the fire floor. The stairshaft was not actively pressurized. The presence of carbon dioxide (C02) in-concentrations greater than normal ambient levels, at any location outside the fire floor, was interpreted as evidence of "smoke" spread. |
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