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P118i Ultrasonic Flowmeter and Analyzer
Reversion: 3.0.0 Page 18 of 49
3. Transducer Installation
3.1 Installing the Transducer
Before installing the transducers, clean the pipe surface where the transducers are to be mounted. Remove any rust,
scale or loose paint and make a smooth surface. Choose a section of sound conducting pipe for installing the
transducers. Apply a wide band of sonic coupling compound down the center of the face of each transducer as
well as on the pipe surface, ensure there are no air bubbles between the transducers and the pipe wall, and then
attach the transducers to the pipe with the straps provided and tighten them securely.
Note:
1. The two transducers should be mounted at the pipe
’
s centerline on horizontal pipes. Make sure that the
transducer mounting direction is parallel with the flow.
2. During the installation, there should be no air bubbles or particles between the transducer and the pipe wall. On
horizontal pipes, the transducers should be mounted in the 3 o
’
clock and 9 o
’
clock positions of the pipe section in
order to avoid any air bubbles inside the top portion of the pipe.
3. Refer to 2.15 for the Transducer Mounting Spacing.
4. If the transducers cannot be mounted horizontally symmetrically due to limitation of the local installation
conditions, it may be necessary to mount the transducers at a location where there is a guaranteed full pipe
condition (the pipe is always full of liquid).
3.1.1 Transducer Mounting Methods
Three transducer mounting methods are available. They are respectively: V method, Z method and N method.
The V method is primarily used on small diameter pipes (DN100~300mm, 4"~12"). The Z method is used in
applications where the V method cannot work due to poor signal or no signal detected. In addition, the Z method
generally works better on larger diameter pipes (over DN300mm, 12") or cast iron pipes.
The N method is an uncommonly used method. It is used on smaller diameter pipes (below DN50mm, 2").
3.1.2 V Method
The V method is considered as the standard method. It usually gives a more accurate reading and is used on pipe
diameters ranging from 25mm to 400mm (1" ~ 16") approximately. Also, it is convenient to use, but still requires
proper installation of the transducers, contact on the pipe at the pipe
’
s centerline and equal spacing on either side
of the centerline.
Downstream Transducer
Upstream Transducer
Flow
Transducer Space
Flow
Side View Top View Section
Pipe Strap
Transducer
3.1.3 Z Method
The signal transmitted in a Z method installation has less attenuation than a signal transmitted with the V method
when the pipes are too large, there are some suspended solid in the fluid, or the scaling and liner are too thick .
This is because the Z method utilizes a directly transmitted (rather than reflected) signal which transverses the
liquid only once. The Z method is able to measure on pipe diameters ranging from 100mm to 5000mm (4" to 200")
approximately. Therefore, we recommend the Z method for pipe diameters over 300mm (12" ).