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The Basics of Compressed Air Drying

To get the best performance from your compressed air system it’s necessary to control the amount of water present.  Compressed air contains water in both liquid and vapor forms.  Liquid water washes lubricant from air operated equipment and accelerates wear.  It also mixes with substances that compressed air is used to move and degrades the performance or results of the process.  Water mixing with paint in a spray gun ruins the paint job.  Water mixing with sand blast media creates clogs in hoses and nozzles.  The vapor form of water doesn’t cause problems for the most part – unless it’s cooled down to a temperature at which it condenses into a liquid.  Unfortunately, every time compressed air is expanded through an orifice – like the throttle of an air tool, or a control valve or a spray gun, it experiences some cooling.  If it’s cooled enough, you get liquid.

The big question is: How dry does compressed air need to be for what you need it to do?  Bearing in mind that drying compressed air costs money, and that the more dry you make it, the more it costs, you will want to make the right choice - The experts at Cal can help!

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Zeks Compressed Air Dryers MTA Compressed Air Dryers Champion Compressed Air DryersSMC Compressed Air Dryers

Sullivan Palatek  Desiccant Air Dryers General Air Products  Desiccant Air Dryers


By far the most popular type of dryer, refrigerated air dryers are reasonably priced, economical to operate, provide a stable pressure dew point and do not require much maintenance.  Most provide a pressure dew point of 35°F, but some less expensive models with smaller refrigeration systems are rated for the higher dewpoint of 50°F.  There are two types of refrigerated air dryers: Cycling and Non-cycling. More about Refrigerated Air Dryers...

  Refrigerated Dryer


Desiccants are substances that attract and hold water very well.  When you purchase a product that could be damaged by the presence of water you often find a little envelope full of what looks like small beads packed inside the box.  This is desiccant.  Two types are commonly used: activated alumina and silica gel.  Unlike the salt tablets used in the deliquescent dryer, these desiccants don’t dissolve when they absorb water.  They fill up with as much water as they can hold and maintain their shape.  Once they’re full they need to be replaced or be regenerated (have the water removed).  Some desiccants are treated with chemical indicators to change color when regeneration or replacement is needed. Learn more...



These dryers pass the compressed air through a membrane with pores large enough to allow air molecules through but not large enough to allow water molecules through.  A purge flow of dry compressed air is passed over the membrane to pick up the collected water and carry it out of the dryer.  The lower a dew point is needed, the more purge air is required.  These dryers are limited in sizes and are usually installed on small, point of use applications. Click here for more details


A deliquescent dryer is basically a tank full of salt tablets. As the compressed air passes through the salt, the salt attracts water and dissolves into a brine that can be drained off.  These are the least expensive dryers to purchase and maintain because they have no moving parts and require no power to run.  The operating cost consists of the cost of more salt tablets plus the freight to bring them in. Learn more about Deliquescent Dryers