The cooled air is reheated to room temperature upon exiting the dryer and before being used.
The are 2 main subtypes of refrigerant dryers:
Refrigerated air dryers are the most common type of compressed air dryer. They are perfect for most manufacturing and service applications, provided you just need dry air without any perceptible moisture.
A few benefits of refrigerant air dryers
In need of a compressed air dryer system capable of lower dew points? Then a desiccant air dryer is a better fit for you.
A desiccant air dryer is a subtype of the adsorption air dryer system. They use a porous hygroscopic medium like activated alumina and silica gel to extract moisture from the air and dry it. They have a dew point of around -40°C or -40°F.
As stated in this succinct guide to air dryers, desiccant air dryers are better suited for second stage drying as the hygroscopic medium would otherwise get saturated too quickly. That means they are usually the second step after a primary dryer like a refrigerated dryer.
There are 2 main types of desiccant air dryer:
The first canister contains a hygroscopic medium through which the air passes. When the medium becomes saturated, the air flows to the second canister for the same treatment.
The first canister then heats up a small amount of air to purge the first medium from moisture and expels it into the atmosphere, resetting the medium.
The regeneration of the medium uses 1 of 2 working principles:
The regenerative nature and low dew point of desiccant dryers, make it perfect to compress air at or below the freezing point.
Some advantages of a desiccant air dryer
The second type of adsorption dryer systems is the deliquescent air dryer. Like desiccant dryers, they pass the air through a hygroscopic medium to dry it.
Contrary to desiccant air dryers, deliquescent air dryers use soluble salt tablets instead of a medium that needs regeneration. The resulting brine needs to be drained and the tablets replaced every so often.
Deliquescent air dryers’ dew point fluctuates depending on the temperature of the atmospheric air coming in.
Deliquescent air dryers are perfect for remote or hazardous environments like landfills, asphalt factories, wood working factories and similar, often industrial, environments.
Benefits of deliquescent air dryers
Because of the added maintenance costs and minimal range of use, Mark decided not to provide deliquescent air dryers.
For a consistent dew point, refrigerant dryers and desiccant dryers will better serve you.
Download your copy of our guide to adsorption air dryers.
The final type of air dryer for your compressor, is the membrane air dryer. As the name indicates, it runs incoming air over a hygroscopic membrane to rid it of moisture.
The air builds up on the membrane until it migrates through to the other side, which is low pressure. A dry gas is then run through, carrying the moisture away for expulsion.
Like deliquescent air dryers, membrane air dryers’ dew point depends on the temperature of incoming air, although a proper setup will result in incredibly low dew points. They are often a second or even third stage dryer.
Membrane air dryers are a popular choice for medical use thanks to the low dew point in a controlled environment resulting in small amounts of high-quality air. If you need an air dryer for a laboratory, dentist’s office or hospital, this is your best bet.
Reasons to go for a membrane air dryer