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Author
Mangs, J. | Keski-Rahkonen, O.
Title
Full Scale Fire Experiments on Electronic Cabinets.
Coporate
VTT-Technical Research Center of Finland, Espoo
Report
VTT Publications 186, June 1994, 87 p.
Keywords
fire safety | fire tests | circuits | cables | ignition | propane | burners | temperature | thermal radiation | oxygen consumption | smoke | gas flow | carbon dioxide | carbon monoxide
Identifiers
electric devices; cabinets; electric appliances; electric utilities; electric connectors; cables (ropes); rates (per time)
Abstract
Three full scale fire experiments on electronic cabinets have been carried out. In the experiments one cabinet, the fire cabinet, was fitted with cables, circuit boards, circuit board rails and connectors and wiring behind the connectors. A mock-up cabinet made of thin steel sheets was attached to the fire cabinet in order to study the response of an adjoining cabinet to the fire. Another cabinet was placed at a distance of 1 m opposite the fire cabinet to represent a neighboring row of cabinets. The fire cabinet was ignitied with a small propane burner located at the botton of the cabinet. Rate of heat release by means of oxygen consumption calorimetry, mass change, CO₂,CO and smoke production rate, concentration of O₂, CO₂ and CO in the fire cabinet, gas flow velocity in the fire cabinet and gas and wall temperatures in all three cabinets were measured as a function of time. A rough estimate for the pwer and energy needed for cable bundle ignition was obtained. Similarly, fire growth rate after ignition was determined as well as time needed for ignition in the adjoining cabinet. A simple buoyant vent flow model is presented which serves to explain observed burning rates after flashover. The burning in the cabinet was found to be oxygen limited with incomplete mixing. A calculation formula for the rate of heat release after flashover in the cabinets is proposed.