How to Detect Compressed Air Leaks

In our last article, we revealed the high costs associated with a leaky compressed air system. How can these leaks be detected?

Leaks can be found in any part of a compressed air system, from the compressor to the points of use. Common problem areas include:Set icons of air compressor and accessories isolated on white.

  • Couplings
  • Hoses
  • Tubes
  • Fittings
  • Pipe joints
  • Disconnects
  • Thread sealants
  • Condensate traps
  • Shut-off valves
  • Pressure regulators
  • Filters
  • Lubricators
  • Bag houses
  • Cylinder rod packing

There are three commonly used methods of compressed air leak detection: listening/feeling, soapy water application, and ultrasonic.

Leak Detection Method 1: Listening and Feeling

A low-tech way to detect compressed air leaks is to listen for them, then feel for leaking air. This only works for very large leaks with direct physical access, and it can be difficult to hear leaks over the noise of the equipment. For these reasons, this method only works in very limited cases.

Leak Detection Method 2: Soapy Water

In this method, soapy water is applied with a paint brush to areas where a leak is suspected. If there is a leak, soap bubbles will form.

While reliable, this leak detection method can be time consuming. It requires direct physical access, meaning leaks in hard-to-access areas of the piping system will go undetected. It also does not indicate which leaks are losing the most air, so there is no way to prioritize leak repairs.

Leak Detection Method 3: Ultrasonic Leak Detection

The industry standard and best practice is to use ultrasonic leak detection equipment. These portable devices typically consist of directional microphones, amplifiers and audio filters, and have either earphones or visual indicators to help the user detect leaks.

The equipment works by detecting the high frequency “hissing” sound created by compressed air leaking into the atmosphere, which is inaudible to the human ear. The sound is both directional and localized to the source, pinpointing the location of the tiniest leaks even in noisy environments.

Unlike the other two methods, ultrasonic leak detection doesn’t require direct physical access to the leaks. Some devices can estimate the volume of air leakage, so repairs can be prioritized.

Next Steps

Once detected, each leak should be tagged and given a unique identifying number or code. Information on each leak should be recorded in a spreadsheet, including the location and severity (volume of air lost). From there, leak costs can be calculated and repairs prioritized.

This process is part of a larger compressed air audit available from C&B. During a seven day air study in your plant, we detect leaks as well as measure cfm, pressure and amp load in the main air lines. The audit consists of air flow measurements, energy and pressure recordings. We offer a completed spreadsheet and recommendations for lowering energy costs, reducing wear on equipment,and increasing production efficiency.


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