Instruments And Technologies Used For Electronic Leak Detection

Ultrasonic Leak Testing TechnologyUltrasonic

Ultrasonic leak detectors are very sensitive to sound. When properly calibrated, a high-quality ultrasonic leak detector will enable users to hear the blink of a human eye. 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.

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.


Drawbacks 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.


Past Methods of Leak Detection: Slow & Impractical

Until someone comes up with an automatic leak detection alerting system, you’ll have to detect them manually by conducting regularly-scheduled systematic checks using an ultrasonic leak detector. But, some companies are reluctant to do so because the equipment to detect leaks isn’t fast and easy to use. And if isn’t being used, it isn’t doing much good.

Detecting a compressed air or steam trap leak is a two-step process. First you have to be aware that there is a leak and then you have to be able to pinpoint where it’s coming from. The solution is an ultrasonic leak detector diagnostic tool that combines both of these steps in a single unit. Ideally, it’s easy to use and quick to spot a leak. Otherwise, the tests won’t get performed on a regular basis. And if the tests don’t get done, the leaks will persist and the money will continue to flow out the door.


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

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.


Signs Of Water Leaks

An unusually high water bill combined with the reading of a water meter can show there is a water leak inside a home. This could also be the case if there is mold or mildew on non-shower walls. Walls, flooring, and ceilings that are sagging as well as stained or damaged can all be signs of a water leak.

Hydrostatic Pressure Test

This is an effective pressure test done on a structure’s sanitary sewer system. It can detect any water leaks that may exist in an underground plumbing system. This test involves placing an inflatable test ball into a structure’s main line sewer cleanout. It is then inflated and obstructs the main sewer line. The plumbing system is then filled with water up to its slab level. The water is observed for approximately 20 minutes. Should the plumbing system not be able to go up to slab level, or the water recedes, it is evidence of water leaking.