Tokyo Keiki UFL-30, Руководство по установке и эксплуатации

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III- 49
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 ø1,000mm will result in a measurement error
of approx. 0.7%.
III-5-4. Installation location
4.1 What straight length of pipe is necessary?
The general upstream straight pipe length necessary for ultrasonic measurement to achieve fully
developed and rotating symmetrically is more than 10D (‘D’ being the upstream pipe diameter), and
more than 5D downstream in order to ensure measurement accuracy.
Please reference Chapter III-4-2 ‘Pipe conditions and required straight pipe length’.
4.2 Can the required upstream straight pipe length be shortened similar to electric magnetic
flowmeters?
Basic specifications for ultrasonic flowmeter measurement is based on 1 path measurement
(single axis of measurement), but it may be possible to achieve stable measurement even shorter
than the straight pipe length requirement if multi-path measurement (2 or 4 paths) is employed.
4.3 What is the affect on measurement if water enters the pit (measurement equipment chamber)?
The standard sensors are of waterproof construction conforming to IP67.
Submersible transducers (IP68) are also available (option). However long periods of submersion
tends to accelerate degradation of transducers, so as much as possible sensors should not be
submerged.