Protection of sensitive pneumatically operated equipment and processes, freeze protection for air lines exposed to low ambient temperatures, Processes where dew point spikes cannot be tolerated

Pet blowing machine, Air circuit breaker, High pressure gas filling, High pressure pneumatic testing of various equipment & components, High pressure H2 gas dryer for turbine cooling, Process gas applications, Light Processing, Petrochemical, Automotive, Manufacturing, Oil and Gas, Painting, Pneumatic tools, Pneumatic control systems, Dental Office air, Truck and Train Air brake systems, Science Laboratories

A compressed air dryer is a device for removing water vapor from compressed air. Compressed air dryers are commonly found in a wide range of industrial and commercial facilities.

Most compressed air users understand that air dryers are essential in any air system. The question is not so much whether an air dryer is needed, but which is the best, most cost-effective solution for a particular application

The process of air compression concentrates atmospheric contaminants, including water vapor. This raises the dew point of the compressed air relative to free atmospheric air and leads to condensation within pipes as the compressed air cools downstream of the compressor.

Excessive water in compressed air, in either the liquid or vapor phase, can cause a variety of operational problems for users of compressed air. These include freezing of outdoor air lines, corrosion in piping and equipment, malfunctioning of pneumatic process control instruments, fouling of processes and products, and more.

Water vapor is removed from compressed air to prevent condensation from occurring and to prevent moisture from interfering in sensitive industrial processes.

There are 3 forms of water in compressed air

Liquid water
Aerosol (mist)
Vapor (gas)

Air-water separators remove liquid water aerosols. They remove up to 99% of the liquid water mist and none of the water vapor. Water in Aerosol or Vapor form is more difficult to remove and requires the use of a Compressed Air Dryer. For every 20°F 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, repairs and product spoilage.

Dew point is the temperature at which water vapor in compressed air starts to condense, or change from a vapor state to a liquid. Air becomes fully saturated when it compresses to 100 psig. The compression process adds heat, and hot air can hold more moisture than cooler air, so the moisture remains in a vapor state. If the compressed air is left untreated, the water vapor will condense in the piping system, causing harm to downstream pneumatic equipment and processes. Air Dryers help prevent this damage. Dehydrating compressed air is most commonly done with a refrigerated air dryer. Refrigerated air dryers remove moisture by chilling compressed air in an evaporator surrounded by liquid refrigerant.

To determine which industry classification you require, ask your self these simple questions:

Does compressed air quality affect my production process and the quality of my end products?

Will poor compressed air quality decrease my productivity,cost savings and product quality standards?

What internal and external ambient conditions affect the quality of my compressed air produced by my system?

If answer of all above question is in yes, than you must require compressed air dryer

How to Select a Compressed Air Dryer

Water vapor is a major contaminant in compressed air systems. Additional cooling of the compressed air as it is distributed throughout the plant air causes the water vapor to condense into water. This condensed water will rust and corrode system piping and damage downstream components requiring dry air. These results in lost production, plant downtime, increased maintenance costs, and reduced air system efficiency. Consider the following guidelines when selecting a compressed air dryer.

Selection Considerations

1. Flow Rate (scfm)
2. Operating Pressure (psig)
3. Air Inlet & Dew Point Temperature
4. Ambient Temperature
5. Application & Environment
6. Filtration

1. Flow Rate

Determine the maximum capacity based on your system. This is normally in scfm and can be determined by your air compressor horsepower if you don't know. The approximation of the air compressor horsepower times 4 will get your close to the flow rate needed. (Example: 25 HP x 4 = 100 scfm flow)

2. Operating Pressure

Determine the minimum/maximum operating pressure based on your system. Dryers are rated at 100 psig. If your pressure increases, the moisture load is decreased, reducing the strain on the refrigeration system. As a rule of thumb, an increase in capacity of approximately 20% for every 25 psig increase from 100 psig can be estimated. For every 25 psig decrease from 100 psig, your capacity is reduced by approximately 20%.

3. Air Inlet & Dew Point Temperature

Determine the minimum/maximum operating air inlet temperature based on your system. Then determine the dew point requirements for the application, and then select which dryer type will produce that dew point. (Desiccant, refrigerated, deliquescent, or membrane) Choose a dew point temperature below the lowest ambient temperature the compressed air system will be exposed to. Consider air airlines located in air-conditioned or unheated areas running underground or between buildings.

To calculate your dew point temperature, take the lowest air temperature and lower it by 20º. (Example: Lowest ambient temp. 58ºF – 20ºF = 38ºF dew point) Typical applications can utilize a refrigerated dryer. More critical applications that require low moisture in the air-line require a desiccant dryer. (Desiccant dryers have ¼% to 0.5% relative humidity in the dry air). The lower the dew point, the dryer the air

4. Ambient Temperature

Determine the minimum/maximum operating ambient air temperature based on your system. During hot summer months, higher ambient temperatures result in higher inlet temperatures and can result in overheating a refrigerated dryer. If your ambient temperature is over 100ºF, this may exceed the maximum inlet temperature of dryer. Therefore, you may need to go to the next size dryer or select a high temperature dryer.

5. Application & Environment

All of the above specifications will help narrow the gap between what type of dryer the system requires to fit its application and environment. Other factors like indoors/outdoors, weather, and location all can change these factors. How the air is used in the application is the most critical part in selecting the type of dryer. Refrigerated dryers have some moisture present in the outlet air, about 10% to 20% relative humidity. Most applications can use a refrigerated dryer based on their needs. Desiccant dryers have very low moisture present in the outlet air, less than ½% relative humidity. They are used in higher quality air instrumentation applications, which provide a pure stream of air.

6. Filtration

Clean, oil-free, compressed air is necessary for most applications. Be sure you have particulate prefilters and oil removal afterfilters installed to provide the best quality air possible.