What is Ultrasonic Sound? How Does the Ultrasonic Leak Detector Work?

ULD
Ultrasonic Leak Detector locates compressed air leak

Many times when working with our customers and educating them about ultrasonic sound and how the Ultrasonic Leak Detector works, we will get questions like, “You sell the Ultrasonic Leak Detector for compressed air, but will it work to detect Helium or Nitrogen?”

The answer is yes, it has the capacity to sense either of these gases. When any gas flows through a small opening at a rate greater than 10-5 mL/second, the gas is generally understood to be in viscous flow. The greater the pressure difference across the opening, the greater the velocity of the gas moving from high pressure to low pressure side. When the velocity increases, the frequency of emitted ultrasonic noise also increases to higher frequency. And to be clear, the Ultrasonic Leak Detector has the capability to detect many different sources of ultrasonic noise. It does not have to be a gas leak, but for our purposes in dealing with the location of compressed air leaks we will stick to gas leaks in this discussion.

Ultrasonic frequencies range from 20 kHz to 100 kHz, a range that is above the perception of normal, human hearing (20 Hz – 20 kHz). The Ultrasonic Leak Detector consists of a microphone and some electronics that “tune” the device’s capability to sense frequencies in this range. And through a process called “heterodyning” the ultrasonic frequency is shifted down into a frequency range that can be heard through a set of headphones by the operator. Ultrasonic noise is highly directional. As the detecting microphone is aimed in the direction of an ultrasonic noise source, the “white noise” heard through the head phones will increase in volume thus indicating that the operator has the detector pointed in the correct direction and can proceed closer to the noise source (meaning compressed gas leak) so it can be identified, tagged and eventually repaired.

Compressed air leaks can result in a waste of up to 30% of a facility’s compressor output. A compressed air leak detection and repair program can save the facility this wasted air. You can even think of such a program as another way in which a facility can “find” additional air compressor capacity for new projects instead of having to purchase additional compressors to make up for the leakage. And the nice thing is that using the EXAIR Ultrasonic Leak Detector to identify only one leak has the great potential to pay for the tool you used to find the leak within the first 3 – 6 months. There aren’t many tools that can pay for themselves in that quick a time frame.

If you have any questions about ultrasonic noise, the EXAIR Ultrasonic Leak Detector or your specific application, kindly contact our Application Engineers to discuss your case today! If you would like to watch my video about how to operate the Ultrasonic Leak Detector, click here.

Neal Raker, International Sales Manager
nealraker@exair.com
@EXAIR_NR

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