Air tank absorbs the pressure wave in the compressor output. It provides smooth air pressure without sudden change. Compressor stores the air in adequate quantity in order to fulfil the sudden air requirements out of the capacity. Air tank capacity is determined according to compressor capacity and type of air requirement. Capacity of air tank at liter can be selected from 6 to 10 times of the compressor capacity as liter/seconds. The second benefit of the air tank eases the condensation of the moisture in the air and discharging the condensation. Water accumulated at the bottom of the air tank as a result of the condensation of the moisture should be removed out of the system by means of traps (automatical discharge devices).