Feb 272013

Using properly fitted and maintained high quality paint booth filters will undoubtedly improve the finishes coming out of your paint booth.  But proper maintenance doesn’t stop with filters.  Other areas of your operation must be continually maintained and monitored.  One often overlooks areas is the quality of your compressed air.  More specifically is your compressed air free of water and water vapor?

One cannot overemphasize the importance of clean, dry compressed air.  When minuscule particles of water find their way from your compressor through your air lines and into the nozzle of your paint gun, blemishes and fish eyes will develop in your paint job.

So what do you need to know to ensure your compressed air is moisture-free?

The first step involves a brief review of how an air compressor operates.  In an air compressor, there are two major parts – a compressing system and a power source.  The compressing mechanism will most likely be either a piston or screw.  Power is supplied by an electric or natural gas motor.  The basic air compressor takes atmospheric (i.e., normal) air and draws it through the compressing mechanism which causes the air’s volume to decrease / compress.  The now compressed air is either used immediately or contained in a vessel to maintain its pressurized state until needed.

Moisture is even more pronounced in compressed air.  Why?  Because you are taking say 5 cubit feet or atmospheric air and compressing it to 1 cubit foot of compressed air; however, the process of compressing the air also compressed the water in the air.  Moreover, as you may recall from basic physics, using energy generates heat and this heat is imparted into the compressed air.  As hot air cools when it moves from your compressor throughout your shop via air lines and hoses, compressed air has a tendency to condensate creating water in your air lines.

So now you know that compressed air will naturally contain moisture.  To eliminate moisture, you must make one of the single most valuable purchase for your shop to ensure the delivery of moisture free compressed air — refrigerated dryers or desiccant air dryers.

  • Refrigerated Air Dryers are the most economical type of dryer.  Warm and saturated air from the air compressor is cooled to a temperature of 35°F to 50°F.  At these temperatures, the water condenses and can be mechanically separated and discharged from the system.  Air, now free of liquid moisture, can be reheated and discharged into the compressed air system.  This air now has a 35°F to 50°F pressure dew point, which means the air temperature has to drop below this temperature before further condensation occurs.
  • Desiccant Air Dryers are dryers are used in applications that require compressed air at dew points as low as -100°F.  Through two identical drying towers, each containing a desiccant bed, air flows alternately.  While one tower is on-stream drying, the other is off-stream being regenerated.  Purge air is used to regenerate the desiccant.  Diameter and length of desiccant beds determine drying efficiency.

Air drying systems (and frequent maintenance thereof) are the single most important factor to achieving moisture-free air.  And when your air is dry, you’ll eliminate many of those paint imperfections, leading to a lower total cost of ownership for your shop combined with raving customer reviews of your work.

 Posted by at 11:41 AM

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