Control Distribution-Natural Movement of Air...

In normal ventilation practice, air is considered to be incompressible, since static pressure varies only slightly from atmospheric pressure. However, in systems where extreme pressures are required, these introduce problems of air density, compressibility and viscosity which are not easily solved.

Air will always take the path with least resistance, therefore, if the design does not provide for proper distribution, a natural balance of the air will occur; that is, the air volume will distribute itself automatically according to the resistance of the available flow paths.

Two known methods used by PV were introduced by The American Conference of Industrial Hygienists & American Society of Heating, Refrigerating and Air Conditioning Engineers, Inc. (ASHRAE). Listed here are the two methods, :

Method A: Normally selected for highly toxic materials to safeguard tampering with blast gates. This method is mandatory where explosives, magnesium and radioactive dusts are concerned, as the possibilities of accumulations in the branch caused by a blast gate is eliminated.

Method B: is used for situations where demands are less stringent.