Dwyer PUX - Manual (Page 84)

11- 4
Normal
• Perform zero adjustment
again after making sure water
flow has stopped completely.
• The measured value, just
when ultrasonic wave cannot
be propagated, is held.
Normal
• A difference of 1% in inner
diameter causes an error of
about 3%.
• Input specifications correctly.
• Input scale as lining.
Select a different location of
sensor mounting (move the up-
stream side of a flow disturbing
element).
• Mount the sensor at different
angles with respect to the
cross section of pipe to find
the location where mean value
is obtainable. The mount the
sensor at that location.
Precipitation is more when the
cross section of pipe has a
smaller area.
Shift the sensor to the vertical
portion of pipe.
Measured value is not
zero though water flow
has stopped.
• Water is subjected to convection in
a pipe.
• Zero adjustment has been
performed.
• When water flow stops, pipe is not
filled up with water or becomes
empty.
• Input piping specifications are
different from actual ones.
• Because of an old pipe, scale has
stuck.
The length of straight pipe portion
is inadequate.
10D and 5D are required at least
on the upstream and downstream
sides.
Flow disturbing element should
not be present within 30D on
upstream side.
Pump, valve, flow joining pipe or
the like is unallowable.
• Pipe is not filled with water or
mud and sand have precipitated.
Measured value has an
error.
State Cause Remedy
BULLETIN F-68