Myths of Compressed Air

Compressed air is free - as a power source it is nine times more expensive to use than electricity.

More pressure is better - raising pressure system-wide will require more power on-line. Pressure problems are best solved at the point of use where they exist, not with more power in the compressor room.

"Our system operates at 100 psiG" - not likely since most compressed air systems have pressure variations of 10% before the air leaves the compressor room.

Production needs 100 psiG - maybe one or two applications are thought to require 100 psiG, but for the most part the true minimum requirement for the majority of the plant is much less.

Reducing compressor operating pressure will save energy - how far pressure is reduced will determine the savings, the further it is reduced the less stable and reliable the system will become. The first time production is interrupted operating pressure will be returned to previous levels and savings will disappear.

Increasing compressor operating pressure increases operating costs - while it is true that compressing a cubic foot of air to a higher pressure requires more energy, overall operating costs will increase only if the entire system is allowed to operate at the elevated pressure.

Receiver sizing rule of thumb: 1 gallon per cubic foot of compressor rating - receivers are sized to manage events in the system, this type of rule of thumb pays no attention to the needs of the system.

Fixing air leaks is an easy energy saving measure - reductions in on-line power are seldom seen until a majority of the system air leaks are repaired. Repairing some leaks in a compressed air system without a Demand Expander™ System or similar pressure control device, can actually cost more money by increasing the volume through the other leaks.

Dryer is better - some facilities install -40° F pressure dewpoint dryers in hopes of fixing their moisture carry over problems. Often the problems have little to do with dryer type. Installing this type of dryer can pose a whole new set of system problems to be dealt with - like adding 15% more compressor power to accommodate the dryer's purge requirements!

A filter removes 99.9999% of 0.01 micron particles - filter performance is tested per the DOP (dioctylphthalate) test that measures the amount of carry over downstream of a filter being tested. DOP is used because it consistently generates particles that range in size between 0.3 - 0.6 micron with little variance. A claim that a filter can remove smaller particles is based on the results of this test and variances in filtering media, not actual results with 0.01 micron particles.

Many of the assumptions listed above are real barriers to operating compressed air systems efficiently. Education is the best first-step measure that can be taken in improving compressed air system operating efficiency. The Compressed Air Challenge is a voluntary collaboration of industrial users, manufacturers, distributors, state and federal energy agencies, industry associations, consultants and utility companies. The goal is to provide education and technical training to improve compressed air systems. For more information, please contact PSI or the Compressed Air Challenge at 1.800.862.2086,