There are 3 techniques that can facilitate your work in the field: the shielding technique, the covering technique, and reflection management.
1. Shielding technique
This technique greatly reduces the influence of interfering leaks. It consists in using a piece of cardboard or foam(*)… to create a barrier between the “parasitic” leak noise and the location where you want to detect/locate a leak.
(*) Any material will work. It will reflect approximately 90% of the energy coming from the interfering leak.
Practical advice: the precision indicator tip placed on the internal or flexible sensor acts as a shield. This technique is very useful when leaks are very close to one another.
2. Covering technique
This technique also greatly reduces the influence of interfering leaks. It consists in:
Either covering an interfering leak with a rag or glove while you inspect an area.
Or covering the sensor with a rag or glove in the zone you want to inspect.
A leaking valve body can be conveniently covered with a cardboard carton too.
3. Reflection management
When searching for leaks, we sometimes get the impression that a leak is coming from a place where there is clearly no compressed air, such as a wall or a partition. This is due to the phenomenon of reflection. Ultrasounds from the leak are bouncing off the reflective surface. You will find the leak by following the angle of reflection. The angle of reflection is equal to the leak’s angle of origin relative to the reflection surface.
Download SDT Leak Surveyors Handbook to learn more!