As a user of compressed air, at some point you are likely to see water appearing in your air distribution system. This can be a nuisance or a serious issue, depending on your application. Should you need to eliminate the problem, it is important to clearly define the results required and specify the right equipment to find the most economical solution.
Where does water in compressed air come from?
Water is present in a gaseous form in the air that is drawn into the compressor. The exact amount of water in the air is called the “humidity” of the air. Other relevant terms to know include the following:
What methods exist to cool saturated compressed air?
• Expose compressed air lines to cooler outdoor temperatures or unheated rooms.
• Use pressure regulators, vortex tubes, expansion vessels, and receiving tanks (pressure reduction).
• Use process equipment such as dryers.
What does “drying” compressed air entail?
“Drying” compressed air means removing water from it. In terms of cost, the more water a technology removes, the higher the cost of drying. But don’t forget to factor in hidden costs. For example, when you permit too much water to remain in the compressed air supply, you pay the price in the form of maintenance, corrosion, or product losses.
Here are the available drying technologies:
• After cooler — Reduces the temperature and water content of the compressed air.
• Water trap — Removes bulk water condensed by the after cooler.
• Drip leg — Controls slugs of water and oil from system upsets.
• Coalescing filter — Removes aerosol water and other liquids which bypass the water traps.
• Pressure reduction — Drying through expansion.
• Refrigeration drying — To dew points of approximately 37°F (3°C).
• Chemical dryer — Reduces dew point by approximately 50°F (10°C).
• Desiccant dryer — Drying to dew points of approximately -40°F to -100°F (-40°C to -73°C).
• Membrane dryer — Variable drying capabilities to approximately -40°F (-40°C) dew point.
View Drying Compressed Air presentation below.
This is part one of a four-part series on drying compressed air.
Drying Compressed Air with Aftercoolers and Coalescing Filters - part 2
Drying Compressed Air with Pressure Reduction - part 3
Drying Compressed Air with a Membrane Dryer - part 4
This series was written by Allan Fish, Product Manager, Parker Hannifin.
Other related posts on compressed air and gas treatment: