Analysis Reliability & Maintenance Center Ultrasound

Heed These Leak-Detection Tips

Jane Alexander | August 17, 2018

Ultrasound signals reflecting off walls or other hard surfaces can be tricky.

According to Allan Rienstra of SDT Ultrasound Solutions, Cobourg, Ontario (, there are three practical leak-detection techniques that personnel can leverage to ease their ultrasound inspections in the field. He described them in a recent blog post on


This technique greatly reduces the influence of interfering leaks. It involves using some type of material, i.e., cardboard or foam, to create a barrier between the “parasitic” leak noise and the location where the user wants to detect/locate a leak. Any material will work as a shield and, essentially, reflect approximately 90% of the energy coming from the interfering leak. When placed on an internal or flexible sensor, the precision-indicator tip of an ultrasound device will also act as a shield. This variation of the shielding technique is particularly useful when leaks are close to each other.


Like shielding, the covering technique also greatly reduces the influence of interfering leaks. It involves covering the leak with a rag or glove while inspecting an area, or covering the sensor in an inspection zone with a rag or glove. A leaking valve body can be covered with a cardboard carton.


Personnel sometimes mistakenly believe that a leak is originating where there is no compressed air, i.e., a wall or partition. This is due to the phenomenon of reflection, wherein ultrasounds from a leak bounce off a reflective surface (see diagram above). In such cases, leaks can be found by following the angle of reflection. This angle is equal to the leak’s angle of origin relative to the reflection surface.

To learn more about leveraging ultrasound and other predictive tools and technologies to keep operations running, go to EP

Ludeca Inc., Doral, FL ( is the exclusive U.S. distributor of products from SDT Ultrasound Solutions.



Jane Alexander

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