19 Troubleshooting
136
UMFLUXUS_G8V4-6-1EN, 2018-10-10
19.5
Large Deviations of the Measured Values
The entered sound speed of the fluid is wrong
A wrong sound speed can result in the ultrasonic signal that is reflected directly on the pipe wall being mistaken for the
measuring signal that has passed through the fluid. The flow calculated on the basis of the wrong signal by the transmitter
is very small or fluctuates around zero.
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 de-
rived from the flow velocity will also be marked as invalid. If several correct measured values are ignored, the totalizer val-
ues 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 (default
2.5 cm/s) has to be set to a low value to be able to measure at low flow velocities.
The entered pipe roughness is not appropriate
The flow velocity of the fluid is outside the measuring range of the transducer
The measuring point is not appropriate
Select another measuring point to check whether the results are better. Because pipes are never rotationally symmetric,
the flow profile is affected. Change the transducer position according to the pipe deformation.
The operating volumetric flow rate meets the expectations, but the standard volumetric flow rate deviates
strongly
The parameters for the measurement of the standard volumetric flow rate have not been entered correctly (see section
16.4).
19.6
Problems with the Totalizers
The values of the totalizers are too high
See
Special Function\SYSTEM settings\Measuring\Quantity recall
. If this menu item is activated, the val-
ues 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 0 manually.
The sum of the totalizers is not correct
See
Special Function\SYSTEM settings\Measuring\Quantity wrapping
. The sum of both totalizers
(throughput) transmitted via an output is not valid after the overflow (wrapping) of one of the totalizers.
19.7
Transmission of Data
The file with the transmitted measuring data contains meaningless strings
The transmission parameters of the transmitter and the transmission program are not identical. Adjust the transmission
parameters of the transmitter (see section 14.2.4) and of the terminal program.