Compressed air is widely used in industries and has ample utility. It is simple to use, but complicated and costly to create. A typical compressed air system consists of compression, cooling, storage, and distribution equipments. The type of compressor most likely to be used for an industrial compressed air system depends largely on size, cost, and reliability requirements. The application norm of compressed air dryers involve climatic conditions, the degree of air dryness needed, cost and consistency.

Compressed air dryers are used for the removal of water and other contaminants from compressed air. One of the most effective ways of drying compressed air is to cool it, collect the moisture that condenses and finally heat the air to the ambient temperature. Compressed air dryers use tools such as refrigeration, desiccant adsorption, and membrane filtration to remove contaminants, particularly water, from the air. Besides, they also use technologies like membrane and in-line compressed air dryers. The air can be dried in single or multiple stages to prevent tool decomposition and other problems associated with water.

Anybody looking for compressed air dryers must take into consideration the drying capacity, pressure, dew point, motor power and operating temperature. Drying capacity is the maximum volume of air through dryer which is usually at 100 psig. The pressure should be at the highest level i.e. the maximum rated inlet pressure of dryer. Dew point is a measure of dryness; it describes how much water vapour is present and gives the measure as to how cold the compressed air can get before the formation of liquid water. Motor power is a reference value often used to approximate dryer size; pressure and capacity. The operating temperature is the full-required range of ambient operating temperature.

The compressed air dryers used in industries can be categorised into three main groups. They are as follows: Refrigerant dryers, Deliquescent desiccant dryers, Regenerative desiccant dryers. Refrigerant dryers cool the incoming air to a temperature or dew point of 1-3'C, causing a large portion of the water to condense and to be collected by a separator. The dew points achieved in deliquescent desiccant dryers are approximately 10'C below the temperature of the incoming air. The desiccant is usually derived from salt or chloride which has a stronger attraction for water than the compressed air being passed through it. The desiccant dissolves with the water and collects in the bottom of the tank which can be easily drained away. Regenerative. desiccant dryers use a desiccant such as silica gel to attract and absorb moisture from the air, achieving pressure dew points in the range of minus 40'C. These lower dew points guarantee that water never condenses in modern systems; even with the super-low temperatures achieved as the compressed air does its work.

Dryers are very much essential for the efficient functioning of compressed air system. Air systems without compressed air dryers severely lessen the longevity of any equipment they operate.