The working of a ventilation system is broadly explained based on two phenomenon in the system i.e. inlet and outlet of air inside the work place and the circulation of the air inside the work place. These two will decide the working of the system. For different kinds of ventilation systems, the operations may not be the same.
Inlet and Outlet of air in the Ventilation System
- The removal of contaminated air and the inlet of fresh air is the main use of the ventilation system. This can be done by the aid of fans and tubes. When the fans are in action, they will change the direction of air or let the motion of the air to be fast.
- Then the air with the motion is allowed to pass through the series of tubes where it is moved out of the working environment as in case of local exhaust or it is mixed with the fresh air in order to make the contaminated air less toxic in the working environment.
- The inlet and outlet movement of the gas or the contaminated air is done by fans and the gases are captured due to the presence of a small nozzle type arrangement called as hood which will not allow the gases to exit from the tubes.
- Take the case of dilution system, in which the inlet air is let into the ventilation system and just made to move from one side of the working place to the other place where it is let out of the tubes by the aid of the exhaust fans.
- Similarly, take the case of the local exhaust system, in which the air is let in at a place and just let out from the other place. Air in the local exhaust system is also subjected to air cleaning.
Circulation of air inside the building
- The circulation of air is to be done in dilution type of ventilation system. The circulation just reduces the concentration of the toxic air inside the working area.
- Circulation of air also involves heat recovery system which maintains nominal temperature in the working area. The circulation is also done by the aid of a blower which will allow the air, in more concentrated area to move to the area in the lower contaminated air or fresh air.
- The main advantage of air circulation is, we need not take fresh air every time from the surroundings and liberate the contaminated air outside. It also saves the excess work.
- Circulation is also performed by creating low pressure region within the working environment so that the contaminated air can be mixed together attaining equilibrium of the pressure.
In a ventilation system, we can either circulate air inside or move the contaminated air completely outside the work place or we can have both in a single system.