DTRS56-04-T-0005A Radiant Heat Attenuation by Clothing and Human Tolerance to Radiant Heat

A series of tests involving the exposing mannequins clothed with normal civilian clothing to a 10 ft. x 10 ft. LNG pool fire was conducted. Both single layer clothing and double layer clothing were used. The radiant heat flux incident outside the clothing and incident on the skin covered by clothing were measured using wide-angle radiometers, for durations of 100 s to 200 s (per test). The levels of heat flux incident on the clothing were close to 5 kW/m2. The magnitude of the attenuation factor (AF) (ratio of the outside radiant heat flux to that on the skin) was calculated. It is seen that AF varies between 2 and higher for ordinary cotton and polyester clothing (of thickness 0.286 mm to 1.347 mm). Values as high as 6 have been measured for clothes of thickness of 1.347 mm. Tests similar to the above were conducted to determine the attenuation factor when a single or multiple sheets of newspaper are interposed in front (about 5 cm) of the radiometer. Singe sheet newspapers reduce the heat flux to the radiometer by a factor of about 5 at a heat flux level of 5 kW/m2. Double sheets reduce the heat flux intensity by a factor of almost 8! The magnitude of the AF for newspaper sheets depends on the magnitude of the heat flux and thickness. It decreases linearly with increasing heat flux values and increases linearly with an increase in thickness.