Compressed Air Dryer

When compressing air you not only increase the pressure and density of the air, but you also decrease the airs ability to contain water. So, if we assume that the temperature is constant, the higher the air pressure the less water mass it can contain.

This is because we are lowering the condensation threshold when pressurising air. The side effect of this is of course condensation of water, everywhere the air temperature fall below the dew point. inside the air system. This creates lots of unwanted effects like malfunctioning of  equipment and tools, corrosion inside system, loss of air volume because it is replaced by water, application failure especially regarding to spray painting and chemical application using compressed air.

There are several ways to dry compressed air. The most common method, used in small systems, is just to let the air cool down inside an air tank. This will give the air time to condensate any moisture that is above the pressurised airs limit. This is also the reason why it is so important to drain air tanks. Failing to drain an air tank minimum once daily can result in an increase in the compressors start/stop intervals, longer running time du to reduced air tank capacity, and even, in some extreme cases, condensed water in the compressed air system downstream of the air tank.

Other alternatives to remove moisture from compressed air is to use moisture filter, or moisture traps. These are basic filters design to trap moisture particles. These filters do not remove evaporated water from the air, they just remove all water condensation droplets contained in the air. The filters come with a bowl where the water is collected. The bowls can be manually drained with a drain valve, or automatically drained via a float mechanism.

For industry, paint shops, and medical clinics, an air dryer might be in it place. These are machines that work on the same principle as an air condition unit, refrigerator, or freezer. The hot, humid, high-pressure air enters the air dryer. Inside the air dryer cooling coils, cooled by refrigerant, cools the air to several degrees below the anticipated lowest temperature of the whole compressed air system. The result is that the humidity of the air is reduced to a point where no condensation can occur anywhere in the system, because the humidity is to low for the air to reach sits condensation point.