Ultrasonic Leak Detection

Ultrasonic leak detection utilizes high-frequency sound produced by a pressurized gas escaping from a vessel to identify a leak. In many applications, simple compressed air is sufficient for leak detection, if the leak is turbulent. Also known as acoustical leak testing, ultrasonic leak testing can be performed with pressure as low as 1 psi, though higher test pressure behind a leak does make it easier to detect and locate. Examples of acoustical leak detection applications include testing plumbing lines, vessels, HVAC system ductwork, and medium to large non-sealed components to determine if they are leaking under pressure or vacuum.

Ultrasonic Leak Testing Technology

Ultrasonic leak detectors are very sensitive to sound. This type of leak testing can be performed in an open or enclosed area and can be calibrated to isolate the sound produced by the leak. Ultrasonic leak detection focuses on a specific frequency band of sound; therefore, wind noise, voices, traffic, and most normal operational sounds can be filtered out and will not affect the accuracy of the test. Depending on the application, ultrasonic detectors will detect pressure and vacuum leaks.

Large leaks typically are louder, provide a lower frequency sound, and are easier to locate than smaller leaks. Ultrasonic leak detectors use a microphone system that senses sound generated by escaping gas in a range of 38 to 42 kHz. Some acoustical leak testing equipment is limited to an isolating frequency band width; these devices may sound false alarms for leaks that are not there, or not find a leak at all. Quality ultrasonic detectors use an electronic process called “heterodyning” to convert high frequency leak sounds to a lower range that allows a hissing leak to be heard through a set of headphones while manually moving the microphone to pinpoint the leak.

Disadvantages of Ultrasonic Leak Detection


Ultrasonic leak detection is not considered a precision leak test method, and ultrasonic equipment typically does not provide automated leak testing, enable users to test to a leak rate specification, provide repeatable accuracy, or provide test result management. Because the average ultrasonic leak detection system will only detect leaks in the 60 sscm range, there are other leak detection methods that provide more accurate and more controlled leak testing.

The accuracy of ultrasonic leak detection is dependent on operator performance, environmental background conditions, and the ability to isolate the sound frequency from background noise. If acoustical leak testing is performed on insulated lines, underground, or routed through walls, the ability to sense a leak can be compromised and the leak may not be detected.

The Leak Testing Experts

Cincinnati Test Systems provides information on acoustical and other leak detection methods to help our customers make informed decisions when selecting a testing method that best fits their leak test application needs. We are recognized as the leader in function and leak test systems, offering calibration, leak, flow, pressure, vacuum, hydraulic, force, tracer gas test, and helium reclaim solutions.

We specialize in production leak test systems, and provide test instruments and leak test systems for a broad range of industries, supporting tens of thousands of test applications globally. We offer turnkey systems that include standard and custom designs, as well as manufacturing and global application support of our leak test solutions.

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