FDT-25W Wall Mounter Ultrasonic Flowmeter
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Examples of optimum locations.
Principles to selection of an optimum location
(1) Install the transducers on a longer length of the straight pipe. The longer the better, and make sure
that the pipe is completely full of liquid.
(2) Make sure that the temperature on the location does not exceed the range for the transducers.
Generally speaking, the closer to the room temperature, the better.
(3) Take the pipe fouling into consideration. Select a straight length of a relatively newer pipe. If the
condition is not satisfying, consider the fouling thickness as part of the liner for a better result.
(4) Some pipes have a kind of plastic liner, and between the outer pipe and the liner there may be a
certain thickness difference that will prevent the ultrasonic waves from direct traveling. Such conditions
will make the measurement very difficult. Whenever possible, try to avoid this kind of pipes. If impossible,
try our plug-in transducers that are installed permanently on the pipe by drilling holes on the pipe while
liquid is running inside.
2.7 Transducers Installation
The transducers used by the FDT-25W 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 optimum position where the straight pipe length is sufficient, and where pipes are in a
favorable condition, e.g., newer pipes with no rust and ease of operation.
(2) Clean any dust and rust. For a better result, polishing the pipe with a sander is strongly
recommended.
(3) Apply adequate couplant to the spot where the transducers are to be installed and leave no gap
between the pipe surface and the transducers.
Extra care should be taken to avoid any sand or dust particles left between the pipe outer surface and
the transducers.
To avoid gas bubbles inside the upper part of the pipe, the transducers should be installed horizontally
by the side of the pipe.