ventilation when dealing with heat
Heat in its pure form, ie not accompanied by other hazards, although rare, but occur. An example is the pump room by compressor, machine rooms, mechanical and extrusion mills in operation without an emulsion, etc.
The so-called hot shops are characterized by heat, which is accompanied gassing, and sometimes dust emission. Wet mills are characterized by co-evolution of heat and moisture.
Considering the fight only with heat, choose to focus mainly na relatively small and most often of low areas. These premises are as naturally ventilated - aerated and mechanically.
Local pumps in these areas are rarely used. However, the intense and concentrated heat to apply them properly. It can be used solid covers, maintenance-free insulated part of a fuel system, as well as parasols and veils, especially the latter.
If you are installing over a heat-generating equipment hoods and curtains to assume that 40 to 75% of the total heat release comes under the umbrella or the veil. The smaller figure refers to the umbrellas, large - to the hangings.
Overweight, or active warm Qu, affecting the air temperature in the room, called the difference between the amount of heat, is not localizable local suction and the total heat loss.
Convective heat in a large part is removed from the work area in a natural way and relatively little effect on its temperature, radiant heat remains largely in the work zone. Excessive heat affects the temperature of the active working area, called the Qu.
The formula determining the length of ventilation when general ventilation for heat removal is of the form:
L = Q [kg / h], (36)
0.24 (/ sp-/ ")
where g - temperature exhaust air; tn - supply air temperature. Currently, there are two ways to determine air for warmth. When one of them operate with excess heat, affect the temperature of the working area, in the calculation formulas are introduced coefficient m and the temperature of working area. For ventilation on a "bottom - up", ie, the introduction of fresh air in the area and removing air from the upper zone, with an extract of the air directly from the working area (local suction, process emissions) calculation formula had the form:
If managed properly determine the value of the first method or the value / bpm during the second, in both cases, the calculation would be accurate. But the coefficient m and the temperature of outgoing air from the upper zone / ud precise definition and can not be found only by experiment.
The coefficient m can be calculated theoretically, but the formula. Coefficient r value rather uncertain and toxnomu calculus can not be. Therefore, taking the value m, obtained by experience and by analogy.
Table. 14, composed of regulatory and literary sources, are the recommended values of m only part of production facilities.