The air drawn from the atmosphere by a compressor is a mixture of gases and water vapor. The capacity of air to hold water in the form of steam, however, is a given variable and it depends primarily on the temperature. If this rises as happens in the compression phase, it also increases the absorption capacity of the water vapor, with the drawback of making the compressed air hardly suited to use.

The transformation of water into condensation occurs only during the cooling phase of the compressed air in the radiator of the compressor, and this is then separated in the cyclonic separator or inside the tank. Nevertheless, the compressed air is 100% saturated with water vapor, and during the subsequent stages of cooling considerable quantities of condensation in the air network and the in the user points.

Without the use of a dryer there is therefore the possibility to find water in the form of condensation, with consequent breakdowns and production interruptions, as well as having to cope with expensive repairs and maintenance.