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PROCEDURE:
1. Use Contact (Stethoscope) Module.
2. Touch downstream side of suspected area and listen through headset.
3. Start test at 40 kHz. If the sound appears weak or confusing, change the frequency. As an ex-
ample, try to test at 30 kHz., then 20 kHz.
4. When necessary, if there is too much sound, reduce sensitivity.
5. Listen for an increase in ultrasound created by the turbulence of partial blockage.
FLOW DIRECTION
Flow in piping increases In intensity as it passes through a restriction or a bend in the piping. As flow
travels upstream, there is an increase in turbulence and therefore the intensity of the ultrasonic
element of that turbulence at the flow restriction. In testing flow direction, the ultrasonic levels will have
greater intensity in the DOWNSTREAM side than in the UPSTREAM side.
PROCEDURE:
1. Use Contact (Stethoscope) Module.
2. Start test in 40 kHz. If it is difficult hearing the flow signal, adjust the Frequency to 30 kHz or to
25 kHz.
3. Begin test at maximum sensitivity level.
4. Locate a bend in the pipe system (preferably 60 degrees or more).
5. Touch one side of bend and note dB reading.
6. Touch other side of bend and note dB reading.
7. The side with the higher (louder) reading should be the downstream side.
NOTE: Should it be difficult to observe a sound differential, reduce sensitivity and test as described until
a sonic difference is recognized.
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