How to Estimate Leaks and the Impact upon a Compressed Air System

In today’s age where compressed air is often referred to as the 4th utility in an industrial manufacturing facility, leaks throughout the system can add up to serious financial losses. It has been estimated that leaks can waste as much as 20-30 percent of an air compressor output.


Not only are leaks a source of wasted energy, they can also contribute to other losses such as:

  • Causing a drop in system pressure, resulting in air tools to function less efficiently
  • Increasing the air compressor on/off cycles which shortens the life of it and other components in the system
  • Increased maintenance costs and more planned downtime for the maintenance to be performed
  • A need to install of additional compressors to make up for the inefficiencies caused by leaks

For compressors that have start/stop controls – the below formula can be used to estimate the leakage rate in the system-

Leakage Equation 1

To use the above formula, the compressor is started when there is no demand on the system –  all air operated equipment and devices are turned off.  As the air escapes the system through the leaks, the system pressure will drop and the compressor will turn on and cycle to bring the pressure back up to the operating level. Measurement of the average time (T) of compressor run duration, and time (t) of the system pressure to drop to the set-point can be plugged into the formula and a Leakage Percentage established.

Another method to estimate the leakage rate is shown below-

Leakage Equation 2

The above method requires knowledge of the total system volume, which includes downstream air receivers, air mains, and all piping.  To perform the check, bring the system pressure up the normal operating pressure (P1) and then measure the time (T) it takes for the system to drop to pressure (P2) which is generally around half the operating pressure.  The 1.25 is a correction factor to normal system pressure, since the leakage rate will be less as the system pressure is lowered.

A leakage rate greater than 10% typically shows that there are areas of improvement (leaks that can be identified and repaired)

Any leakage testing and estimating should be preformed regularly, at least each quarter, so as to minimize the effect of any new system leaks. The tests are only one part of a leak detection and repair program. The best way to detect leaks is the use of ultrasonic leak detector (shown below.)  To learn more about the EXAIR model 9061 Ultrasonic Leak Detector, check out this blog that was previously published.


If you have questions about compressed air systems, or would like to talk about any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or any of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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