Compressed Air Encyclopedia

The Cost of Compressed Air Leakage

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• Compressed Air Management

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Compressed air is one of the most expensive energy sources in the plant environment, so it makes sense to conserve it. But some plants lose up to 30% of their compressed air to leakage alone.

Compressed air is one of the most expensive energy sources in the plant environment, so it makes sense to conserve it. But some plants lose up to 30% of their compressed air to leakage alone.

Compressed air leakage is not only expensive because of the energy that was wasted in generating it, but leakage also causes unnecessary wear on the compressor and other system parts.

Although leaks can occur anywhere in a system, most are located where a fitting connects to a component. Leaks also occur frequently when seals within a component fail allowing the air to escape.

The rate of leakage is proportional to the supply pressure and the area of the hole. This means that a 1/8″ diameter hole loses four-times as much air as a 1/16″ diameter hole.

Leakage rates in CFM at 100 psi supply pressure:

If a leak elimination program is to be implemented, clearly the largest holes should be taken care of first as they represent the largest loss.

A large leak is quite easy to find since the hiss of escaping air can be heard easily, but the smaller leaks can be more difficult to find.

To locate small leaks an ultrasonic leak detector can be used. Leak detectors are extremely sensitive to the ultrasonic sound of a turbulent compressed air leak. The detector usually comes with a set of headphones and works by using a process called heterodyning to convert the ultrasonic sounds of the leakage to lower frequency sounds that can be heard by the human ear. The operator waves the detector past the equipment noting the location of any leaks.

A more low-tech method involves squirting a solution of dish soap to any suspected leak locations. The appearance of bubbles indicates a leak.

Some leaks will be simple items like tightening a loose fitting, while others can be more difficult such as replacing the seals in a component.

Lowering the entire system pressure to a much lower pressure at night and on weekends can also reduce the quantity of leaked air. By not turning off the pressure entirely, machine components retain their state, and do not have to be reset.

Many companies are not aware of the cost of compressing air, and no doubt many more companies would be much more efficient with the compressed air that they generate if they were aware of the cost per CFM.

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