Air Dryers

Why should you use a Dryer for your Compressed Air System?

Water vapour (humidity-moisture) enters the air system through the air compressor inlet air filter. The air compressor sucks in approximately 7 cubic feet of atmospheric air at 0 psig, and that volume of air is compressed into 1 cubic feet of air at 100 psig. The water vapoor (humidity-moisture) that was in the 7 cubic feet of atmospheric air is now compressed into 1 cubic feet of compressed air. 

There are 3 forms of water in compressed air: 

1. Liquid water, 2. Aerosol (mist)  3. Vapour (gas) 

Liquid water is easily removed by general purpose line filters. They remove 98% of the liquid water and less than 10% water mist & 0% vapoor. Water in Aerosol or Vapour form requires the use of a Compressed Air Dryer. For every 10°C drop in compressed air temperature, the moisture holding capacity of air is reduced by 50%. Drying prevents liquid water forming downstream where it can contaminate or damage the system causing operating problems, costly maintenance, and repairs

Refrigerent Dryers – Principle of Operation –
Wet air enters into the dryer and passes through the heat exchanger. The warm wet air entering the dryer is cooled down by the outgoing cold and dried air which reduces load on the refrigerant compressor, saving energy costs.
Next the compressed air passes through the air to refrigerant heat exchanger which cools the air temperature to the pre-set dewpoint. This is set at +2C, water in the air at this stage condenses and turns into water droplets. This condensate is removed automatically by the autodrain as bulk water. (This should then pass into an oil/water separator before going to drain).
Finally, the cool and dry air is reheated by thermally mixing it with the incoming air which also reduces its relative humidity (water-loading), thus preventing pipework corrosion and annoying condensation on downstream pipework.