When things get heated, a Cabinet Cooler can cool things down.

Heated Desiccant Dryer

Many of us have walked into a compressor room.  They are typically a small room that is very warm as it contains an air compressor, a dryer, and other items that create heat.   To help remove the heat, a fan is placed near the ceiling to remove as much heat as possible.  But, when the days get warmer, it makes it more difficult to keep things cool inside the compressor room.  Recently I was working with a pharmaceutical company about the issues with the operation of his dryer.

For this customer, he was using a heated-type regenerative dryer in their facility to get a -40 deg. F dew point.  It was important in their process to have very dry compressed air because it was coming in contact with powders.  As the outside temperatures began to warm up, they started to see alarms and failures with their dryer system.  With a dryer shutdown, they had a potential of water going downstream into their process.  They contacted EXAIR for a solution.

He explained the situation in a bit more detail about his desiccant type dryer.  It had two towers next to each other.  One tower would dry the compressed air while the other tower would be heated to remove any water that was adsorbed by the desiccant.  The control panel was mounted in between the desiccant towers, and it operated the switching valves and heating cycle of the dryer.  When a tower was being regenerated by heat, the ambient temperature around the control panel was getting near 140 deg. F.  With this added heat, the electronics inside would malfunction and shut down the function of the dryer.  They did have a control fan near the ceiling to try and remove the heat from the room, but it was not very effective.  They needed an alternative way to keep the dryer running.  With the location of the control panel between the two towers, there was very little room to work.  He needed something very compact, easy to mount, and effective in maintaining a cool internal temperature.

EXAIR High Temp Cabinet Coolers

In calculating the high ambient heat and the size of the control panel, I recommended the HT4315 High Temperature Cabinet Cooler System.  It is able to handle the high ambient conditions from 125 – 200 deg. F.  With a dimension of 1.34” diameter and a length of 8”, this compact design had no problem fitting onto the panel between the towers.  Even with this small design, the model HT4315 had plenty of cooling capacity to keep the electronics inside from overheating, eliminating the concern with their dryer system shutting down.

To mount this Cabinet Cooler System, a 1 1/8” knock-out hole in the cabinet and a small wire connection hole for the thermostat are the main steps.  This makes it fast and easy to install onto the panel to start getting the cold air to  the electronics.  With a thermostat control, it will only operate the Cabinet Cooler during high temperature conditions, making the system very effective.  The design of the Cabinet Coolers has no moving parts, no motors, no Freon or condensers to clean.  Once they are installed, they are maintenance and worry-free.

If you wish not to have failures in your compressor room during the hot months, a Cabinet Cooler System can be the correct product for you.  If you need help in sizing, you can fill out the EXAIR Cabinet Cooler Sizing form and send it in to us.  For my customer mentioned above, the integrity of their compressed air system was sustained to keep their production process running smoothly.


John Ball
Application Engineer

Email: johnball@exair.com
Twitter: @EXAIR_jb


Heated Desiccant Dryer by Compressor1.  Creative Commons Attribution-NoDerivs 2.0 Generic.

Compressed Air and Dew Point

Today’s discussion is on dew point of air as it has a significant impact on a compressed air system. The dew point is the temperature at which the water vapor in the air  can no longer stay in a vapor form, and condenses from a vapor into a liquid. The amount of water vapor contained in air is directly proportional to its temperature. The warmer the air the more space there is between molecules thus it is able to hold more water vapor.Capture

It is when air temperature drops below the dew point that issues develop in a compressed air system. Let’s take the example of a warm summer day at 90 F and 50% relative humidity. From the chart we see the dew point temperature to be 70 F. So at night, when all the equipment is shut down and the temperatures drop into the 60’s, water will condensate throughout the entire system. In the morning when the equipment is turned on, water blows through sensitive valving.

Compressing air will increase the dew point. Hot compressed air exiting the compressor and cooling while it makes its way through distribution systems is one reason for condensate in compressed air lines. Drying the compressed air is recommended to reduce or eliminate water condensate problems in a compressed air system.

There are several methods to dry out your compressed air. Each have their advantages and disadvantages. The following short review of the various options will help you decide which is best for your application.


The compressor’s after-cooler  which looks similar to a car’s radiator or the condenser in an air conditioner, is the first step to dryer air. It is placed at the compressor’s air outlet and uses either ambient air or water to cool the compressed air and condense some of the water vapor into a liquid that can be removed with a water separator.

The simplicity of design is a positive. The negative is that it can never cool below ambient but something above ambient depending on its capacity. After-cooler performance is rated by approach temperature, which is how closely the compressed air leaving the after-cooler will approach the temperature of the cooling medium used.

For example, if an air-cooled after-cooler is rated for a 10°F approach temperature, and the temperature of the ambient air is 90°F, the temperature of the air leaving the after-cooler will be 100°F. Assuming 50% relative humidity day the dew point will be 80 F.

Mechanical Water Separators


Wet compressed air enters the separator and passes through a set of vanes that spins it in a vortex. Centrifugal force causes liquid to fly out of the compressed air stream and run down the inside of the filter bowl, where it can be drained off. These are installed at the point of use as a final defense before entering sensitive compressed air equipment. They are an inexpensive assurance of quality air. The ones EXAIR has also include a sintered bronze filter element to remove dirt and scale as well as water.

Deliquescent Dryer

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.

Desiccant Air Dryers

These are similar to the deliquescent driers except they use a desiccant that attracts water but holds it. When they have reached their saturation limit they are either replaced or regenerated in one of three methods.

Operating cost of these dryers varies with the method used to remove water from or regenerate the desiccant.

Heatless regenerative dryers take a portion (about 15%) of the dry compressed air leaving the dryer and passes it through the desiccant to absorb the moisture out of it. Purchase cost economical but operational costs are high because if all the compressed air used to dry out the desiccant.

Heated purge regenerative dryers take advantage of the fact that hot air can hold more water than cold air. These dryers take about 5% of the dry compressed air leaving the dryer and pass it through an electric heater and then sends it through the wet desiccant bed. This dryer cost more than the heat less dryer but is offset by using half the compressed of that used by the heat less dryer.

Blower Purge Dryers

These are similar in concept to the had dryers found in restrooms but on a larger scale. Heated air is sent trough the desiccant with a blower. These are not quite as efficient because they are heating up ambient air which would not be as dry as compressed air.

Membrane Air Dryers

These dryers use 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. The lower a dew point is needed, the more purge air is required. These

Refrigerated Air Dryers

Is an A/C system that refrigerate  the compressed air as close to freezing as possible in order to condense out as much water as possible then use a mechanical water separators to remove the condensed water. They require electricity to operate along with the associated cost of operation and maintenance.

Hopefully this gives you a better understanding on how to qualify your compressed air.

Feel free to contact me at any time with questions or concerns, or if I can be of any further assistance. I genuinely appreciate the opportunity! 1-800-903-9247 or click on the live chat icon in the upper left hand corner.

Joe Panfalone

Application Engineer
Phone (513) 671-3322
Fax (513) 671-3363
Web: http://www.exair.com
Twitter: http://www.twitter.com/exair_jp
Facebook: http://www.facebook.com/exair

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