By: Anina Diener

Three Stages of Water Elimination in Compressed Air

Ambient air always contains some level of moisture. When you compress air, the moisture will condense and can cause problems if it isn’t addressed. When an oily water mixture, (the byproduct of condensation) makes its way through the air lines and to points-of-use, it can cause many problems. Blasting and painting processes are affected, along with pneumatic tools, CNC machining centers, robotics, and many other applications.

When a compressor draws in air, it is compressed about 8 times the normal atmospheric pressure in order to achieve 100 PSI. Moisture that is present as a vapor in the air begins to condense. It’s like squeezing the water out of a sponge. Greater amounts of condensation occurs as the compressed air moves through the system and cools. The effect is more pronounced in summer because of higher ambient humidity.

It is impossible to prevent 100% of the moisture from entering your compressed air system, but you must eliminate as much of it as possible. You can do this in stages throughout your system using different filtration components. Here are the three main stages:

  1. The first place of attack is in the receiver tanks. When air emerges from the compressor, it is hot – which temporarily keeps the water in its vapor state. Then, when it gets to the tank, condensation occurs, producing a liquid that will collect at the bottom. Draining the tank is crucial to getting rid of moisture in your air compressor system. Zero Loss, timer-based, and manual drains are standard practices for the reliable draining of receiver tanks.
  2. A mechanical separator is another way to remove water from an air system. A filtration water separator (different than just an average filter) removes large amounts of moisture from the air supply using centrifugal force. This device removes 40% to 60% of the water in a compressed air system. In fact, using this device alone may be liquid-free enough for your application at this point.
  3. If further moisture removal is necessary, look next to refrigerated air dryers. Temperature, pressure and moisture content are correlated. By chilling the air to a lower temperature than ambient, more water is removed. Refrigerated air dryers yield air that is between a 34° and 40° dew-point. This is sufficient for most applications. If this doesn’t dry your air enough, you need to consider another type of dryer.
    1. Desiccant Dryers are used in applications that need extremely dry air such as, painting, printing and instrument manufacturing. It is also a must when compressed air meets ambient temperatures of less than 32°F. Desiccant dryers produce dewpoints from -40°F to -100°F depending on the model of the dryer and the type of desiccant used in the system.

Contact one of our staff for more info on moisture removal for your application!