Pages: 6 Published: Jan 1966
Both the fire hazard and the health hazard are related to the concentration of the vapors in air. The concentration of the vapors will depend upon several factors such as the evaporation rate, agitation, the temperature of the work, the temperature of the air, the extent of exposed surface, the amount and efficiency of local ventilation, and the quantity and efficiency of the general ventilation. The concentration must be kept lower to control health hazard than would be the case for the fire hazard. Lower explosive limits are usually measured in per cent by volume, whereas the acceptable levels or concentrations for the control of health hazards are measured in the parts per million range. In the case of fire hazard, time is not an important factor. The important factors are the build-up of vapors in the air to concentrations between the upper and lower explosive limits and the presence of a source of ignition. In the case of health hazard, both the frequency and duration of the exposure are important as well as the concentration of the material in the workroom air.
Paper ID: STP46194S