WORK PLANS - Laserfiche WebLink

Home Browse Search

�r commercial replacement drinks contain salt, this is not necessary�for acclimatized individuals because ' most people add enough salt to their summer diets. GENERAL VENTILATION i. General ventilation is used to dilute hot air with cooler air(general! cobler air that is Y brought in from the outside). This technique clearly works better in cooler climates than in hot ones. A permanently installed ventilation system usually handles large areas or entire)buildings. Portable or local exhaust systems may be more effective or practical in smaller areas. I i AIR TREATMENT/AIR COOLING I Air treatment/air cooling differs from ventilation because it reduces the temperature of the air by removing heat(and sometimes humidity)from the air. I� Air conditioning is a method of air-cooling, but it is expensive to install and operate. An alternative to air conditioning is the use of chillers to circulate cool water through heat exchangers over.which air from the ventilation system is then passed; chillers are more efficient in cooler climates or in dry climates where evaporative cooling can be used. Local air cooling can be effective in reducing air temperature in specific areas. Two methods have t been used successfully in industrial settings. One type, cool rooms, canbe used to enclose a specific workplace or to offer a recovery area near hot'jobs. The second type is,a portable blower with built-in air chiller. The main advantage of a blower, aside from portability,i!is minimal set-up time. - Another way to reduce heat stress is to increase the airflow or coivection using fans, etc. in the work area (as long as the air temperature is less than the worker's skin itempe�ature). Changes in air speed can help workers stay cooler by increasing both the convective heat exchange (the exchange r between the skin surface and the surrounding air) and the rate of'�evaporation. Because this method does not actually cool the air, any increases in air speed must impact the worker directly to be t effective. L If the dry bulb temperature is higher than 35°C (950F), the hot air passing over the skin can actually make the worker hotter. When the temperature is more than 35°C and the air is dry, evaporative " cooling may be improved by air movement, although this improvement will be offset by the convective heat. When the temperature exceeds 35°C and the relative humidityl'is 100%, air movement will make the worker hotter. Increases in air speed have no effect o°n the body temperature of workers wearing vapor-barrier clothing. HEAT CONDUCTION r* Heat conduction methods include insulating the hot surface that generates the heat and changing the surface itself. I` Simple engineering controls, such as shields, can be used to reduce radiant heat i.e.-heat coming f� from hot surfaces within the worker's line of sight. Surfaces that ;exceed 35°C (95°F) are sources of infrared radiation that can add to the worker's heat load. Flat black surfaces absorb heat more than smooth, polished ones. Having cooler surfaces surrounding the;worker, assists in cooling because the worker's body radiates heat toward them. With some sources of radiation, such as heating pipes, it is possible' to use both insulation and � g P P P.° ; surface modifications to achieve a substantial reduction in radiant heat. ,flinstead of reducing radiation STANTEC Consulting Corporation oration Attachment 8 4' 13 4