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5. Installing C-PT Transducers for the Transit-time Method
Installing the C-PT transducers consists of determining the number of traverses, mounting the clamping fixture to the
pipe and then mounting the transducers into the clamping fixture.
Use the sections that follow to properly install the fixture and transducers.
CAUTION!
A flowmeter's accuracy and performance depends on the location, spacing, and alignment of
the transducers. The transducer spacing is unique to your installation.
5.1 Determining the Number of Traverses
The first step of installation is determining the number of traverses. The transducers can be mounted using one of two
methods (see Figure 2 on page 5):
•
Double-traverse method ("V" method) - transducers are mounted on the same side of the pipe and the ultrasonic
signal is bounced from one transducer to the other, off the opposite pipe wall.
•
Single-traverse method ("Z" method) - transducers are mounted diagonally across from each other. The ultrasonic
signal is transmitted directly from one transducer to the other, across the pipe.
For pipe diameters from 4 to 20 in., always try the double-traverse method because it is easier to configure and yields
greater accuracy. However, if the pipe has poor inside surface conditions or the fluid is highly attenuating, you may not
be able to obtain a reliable signal. Therefore, you should use the single-traverse method. Typically, you should try the
single-traverse method for pipe diameters greater than 20 in. Spacing of the transducers is calculated by the electronics
after all the installation parameters have been programmed into the flowmeter.
•
Universal clamping fixture - page 6
•
General clamping fixture (permanent installation) - page 19
•
Magnetic clamping fixture - page 30
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C-PT Ultrasonic Flow Transducer Installation Guide
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