2.8 Transducers Installation
The transducers used by the
NCM-6
0
3
series ultrasonic flow
meter are made of
piezoelectric crystals both for transmitting and receiving ultrasonic signals through the wall
of liquid piping system. The measurement is realized by measuring the traveling time
difference of the ultrasonic signals. Since the difference is very small, the spacing and
the alignment of the transducers are critical factors to the accuracy of the measurement and
the performance of the
system. Meticulous care should be taken for the installation of the
transducers.
Steps to the installation of the transducers:
(1)
Locate an optimal position where the straight pipe length is sufficient (see the previous
section), and where pipes are in a favorable condition, e.g., newer pipes with ease of
operation and no rust.
(2)
Clean any dust and rust on the spot where the transducers are to be installed. For a
better result, polishing the pipe outer surface with a sander is strongly recommended.
(3)
Apply adequate ultrasonic couplant (grease, gel or Vaseline)* on to the transducer
transmitting surface as well as to the installation spot on the pipe surface. Make sure
there is no gap between the transducer transmitting surface and the pipe surface.
Extra care should be taken to avoid any sand or dust particles left between the pipe surface
and the transducer surface.
Horizontally lined pipes could have gas bubbles inside the upper part of the pipe. Therefore, it
is recommended to install the transducers horizontally by the side of the pipe.
There are three ways to mount the transducers on to the pipe: by magnetic force, by clamp-on
fixture and by hand. If the pipe material is metal, the magnetic force will hold the transducer
on the pipe. Otherwise, you may simply hold the transducer rack and press it against the pipe
if you just need a quick measurement, or, you may use a metal strip or the provided clamp
fixture to install the transducers.
Please see Appendix §8.2 for more installation information.
*Note: It is recommended to use the SOUNDSAFE product from Sonotech, Inc. as the ultrasonic couplant
for safety considerations. Other couplants, such as grease, gel, and Vaseline, can be used as alternatives, but
at your own risk.
2.8.1 Transducer Spacing
The spacing value shown on menu window M25 refers to the distance of inner spacing
between the two transducers (see the following figures). The actual distance of the two
transducers should be as close as possible to this spacing value.
2.8.2 V-method Installation
V-method installation is the most widely used method for daily measurement with pipe inner
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