Engineering Controls
Ventilation, air cooling, fans, shielding, and insulation are the five major types of engineering controls used to reduce heat stress in hot work environments.
1. General ventilation
Ventilation is used to dilute hot air with cooler air (generally cooler air that is 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.
2. Air treatment/air cooling
Air treatment and air cooling methods differ from ventilation because they reduce the temperature of the air by removing heat (and sometimes humidity) from the air. 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.
3. Fans
Fans cool workers by increasing both the convective heat exchange 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 effective.
4. Shields
Shields can be used to reduce radiant heat, i.e. heat coming from hot surfaces within the worker's line of sight. Instead of reducing radiation from the source, shielding is used to interrupt the path between the source and the worker.
5. Insulation
Insulation methods include insulating the hot surface that generates the heat and changing the surface itself. With some sources of radiation, such as heating pipes, it is possible to use both insulation and surface modifications to achieve a substantial reduction in radiant heat.
Knowledge Check Choose the best answer for the question.
5-10. How do fans help to reduce heat stress?
You forgot to answer the question!