Tokyo Keiki UFP-20, Installation & Operation Manual

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3.4 Are there problems with lining detachment from the pipe interior?
Centrifugal force is generally used to bond linings to the interior of pipes and during operation and
the pressure of the water also acts on the lining, so problems with lining detachments are few.
Should such problem occur however, as long as the sensors are not positioned directly at that
point, there should be no adverse affect on measurements. Even if a slight separation of lining
occurs at the point of measurement but not a complete detachment from the pipe wall, water
would fill the space between the lining and the wall, and any deviations may be corrected for by
readjusting the sensitivity of the system. Although not a sure method, a system readjustment or
change in transducer position may enable measurement even in the case of lining separation.
3.5 How does rust or rust scale on the pipe interior affect measurement?
Rust spots in some places in cast iron pipes do not affect measurement. However extensive rust
on entire surfaces may cause errors or mis-measurements. For example, a 1mm accumulation of
rust scale on the entire interior surface of the pipe of DN1000mm will result in a measurement
error of approx. 0.7%.
3.5.4 Installation location
4.1 What straight length of pipe is necessary?
Ultrasonic flowmeter requires “fully developed and rotationally symmetrical flow profile” as
pre-condition. But According to JEMIS032-1987, generally required straight pipe length for
ultrasonic flowmeter is defined as more than 10D (“D” being the upstream pipe diameter)
upstream, and more than 5D downstream in order to ensure measurement accuracy.
Longer straight pipe length might be better to be choosen for ideal condition of measurement.
Please reference Chapter 3.4.2 “General condition for straight pipe length”.
4.2 What is the affect on measurement if it rains?
The standard system with flow transducers are of weatherproof construction IP65 conforming to
IEC60529.
4.3 How far apart can the flowmeter unit and transducers be placed?
Coaxial cable is used to connect the main unit to the transducers. Coaxial cable length is limited
to 157m with extension cable. However installation should also take into consideration external
noise interference.
4.4 What are “Z” and “V” -path methods of measurement?
These refer to transducer placements. The Z-path method (transmission or single-traverse) is
where the transducers are mounted diametrically opposite each other and the ultrasonic signal is
transmitted directly from one transducer to the other across the pipe. This method is used when
the pipe is of adequate diameter or for pipes where acoustic signals are greatly reduced.
With the V-path method (reflection or double traverse) 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