WET TYPE VENTILATION SYSTEM - VENTILATION
Ventilation (the V in HVAC) is the process of “changing” or replacing air in any space to provide high indoor air quality ( i.e. to control temperature, replenish oxygen, or remove moisture, odors, smoke, heat, dust, airborne bacteria, and carbon dioxide). Ventilation is used to remove unpleasant smells and excessive moisture, introduce outside air, to keep interior building air circulating, and to prevent stagnation of the interior air. Ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality may be divided into mechanical / forced and natural types. “Mechanical” or “forced” ventilation is used to control indoor air quality. Excess humidity, odors, and contaminants can often be controlled via dilution or replacement with outside air. However, in humid climates much energy is required to remove excess moisture from ventilation air.
Air washer is a unit used to cool as well as to filter the supply air before producing it into the required space. In this unit the air passed through water Resistant filters where it is filtered and passes through spray bank/cell deck pad/ PVC cooling fills and then finally through the mist eliminator to the blower. The filtered and cooled air is then circulated in the building as required.
DRY TYPE VENTILATION SYSTEM
This is a simple type of ventilation system. It is cheaper than wet type ventilation and efficient also. In this type of ventilation the air passes through two sets of filter like pre & fine, where the air is filtered as per requirement and is supplied to the building with the help of a fan. Mostly this type of ventilation is done in average climate conditions. This will not be suitable for extreme heat climate, where a UAF unit is necessary. Most common arrangement of dry type ventilation is shown in the left side figure.
It is done as per the America conference of governmental industrial hygienists (ACGIH) which is a professional association of industrial hygienists and practitioners of related professions. One of its goals is to advance worker protection by providing timely scientific information to occupational and environmental health professionals.