10 Troubleshooting
FLUXUS F501
10.5 Significant deviations of the measured values
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UMFLUXUS_F501V1-3EN, 2020-06-30
The pipe lining may cause problems during the measurement if it is not firmly attached to the inner pipe wall or
consists of acoustically absorbing material
Try to measure on a section of the pipe free from lining.
Highly viscous fluids strongly attenuate the ultrasonic signal
The measurement of fluids with a viscosity of > 1000 mm²/s is only conditionally possible.
A high concentration of gases or solids in the fluid scatter and absorb the ultrasonic signal and thus attenuate
the measuring signal
A measurement is impossible if the value is ≥ 10 %. If the proportion is high, but < 10 %, a measurement is only conditionally
possible.
10.5
Significant deviations of the measured values
A fluid with a wrong sound speed was selected
If a fluid was selected whose sound speed does not match the actual one, the measuring signal may be confused with the
pipe wall signal.
The flow calculated on the basis of the wrong signal by the transmitter is very small or fluctuates around zero.
There is gas in the pipe
If there is gas in the pipe, the measured flow will be too high because both, the liquid and gas volume, are measured.
The defined upper limit of the flow velocity is too low
All measured flow velocities that are greater than the upper limit will be ignored and marked as invalid. All quantities deviated
from the flow velocity will also be indicated as invalid. If several correct measured values are ignored, the totalizer values will
be too low.
The entered cut-off flow is too high
All flow velocities below the cut-off flow are set to zero. All derived quantities are also set to zero. The cut-off flow has to be
set to a low value to be able to measure at low flow velocities (default: 2.5 cm/s).
The entered pipe roughness is not appropriate
The flow velocity of the fluid is outside the measuring range of the transmitter
The measuring point is not appropriate
Check whether a different measuring point provides better results. Because pipes are never rotationally symmetric, the
flow profile is affected.
10.6
Problems with the totalizers
The values of the totalizers are too high
See
Special Funct.\SYSTEM settings\Measuring\Quantity recall
. If this menu item is activated, the values
of the totalizer will be stored. The totalizer will continue with this value at the start of the next measurement.
The values of the totalizers are too small
One of the totalizers has reached the upper limit and has to be reset to zero manually.
The sum of the totalizers is not correct
See
Special Funct.\SYSTEM settings\Measuring\Quant. wrapping
. The sum of both totalizers (throughput)
transmitted via the output is no longer valid after the first overflow (wrapping) of one of the totalizers.