Dwyer UXF2 - Manual (Page 111)

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Symptom Cause Remedy
(Continued from
preceding page) Ingress of bubbles
Bubbles are introduced if
reading is normal when flow is
stopped.
If mounted immediately
downstream a valve, a cavitation
causes the same phenomenon as
when bubbles are introduced.
Eliminate ingress of bubbles.
z
Raise the pumping well level.
z Check the pump shaft seal.
z Retighten the negative pressure
piping flange.
z Avoid a flow in cascade to
pumping well.
Shift the sensor where bubbles are not
introduced.
z
Upstream from pump.
z Upstream from valve.
Excessively turbid.
More turbid than inflow sewage
water or return sludge.
Scales are on inside wall of old
pipe.
Lining is thick.
Mortar lining or similar is
several ten mm thick.
Lining is peeled.
There is a gap between lining
and pipe.
z Move the detector to smaller pipe
diameter on the same line.
z Move the detector to another place
or pipe.
Sensor is mounted on bend pipe
or tapered pipe. Mount the sensor on straight pipe.
3. Influence by external noise.
z There is radio broadcasting
station nearby.
z There is heavy traffic of
automobiles, trains, etc. near
the measurement site.
z Reduce the length of main unit-
sensor cable to a minimum.
z Connect the main unit and pipe to
ground.
4. Hardware error. See "Section 5.7.6. Remedying a
hardware fault. "
z Water convection in pipe. Normal.
z After zero adjustment. z Recommence zero adjustment at a
status where water is completely
at a standstill.
Measurement value is not
zero while water is at
standstill.
z Pipe is not completely filled or
is empty when water is at a
standstill (LED lit red). Normal.
BULLETIN F-70