50
For all small pipes below 89mm, using 2MHz transducers, the bead of couplant used must be approximately 20mm long and
2mm maximum diameter for the moveable sensor and 30 long and 2mm diameter for the fixed sensor. Using more couplant
could cause wall signals to be generated which cause errors in measurement. On Stainless Steel Pipes the amount of couplant
applied should never exceed the amount indicated in the Examples above. For large Plastic and Steel Pipes the amount of
couplant applied is less critical, however do not use more than is absolutely necessary.
6.2.2
Transducer set "B" and "C"
The main difference between transducer set “B” and “C” is the angle that the crystal has been inserted in the sensor block itself.
The maximum amount of couplant required is a bead 30mm long by 5mm wide.
COUPLANT
30 mm
5mm
Figure 21
