11 Troubleshooting
11.5 Significant deviations of the measured values
PIOX S72*
2022-05-15, UMPIOX_S72xV1-9EN
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11.5
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, a pipe wall signal can be mistaken for the
measuring signal. The flow calculated by the transmitter on the basis of the wrong signal 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 the 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 and
the flow profile is affected.
11.6
Problems with the totalizers
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.
• The sum of both totalizers (throughput
Q
) transmitted via an output is not valid after one of the totalizers has overflowed
for the first time.
An interrogation point is displayed after the value of the totalizer.
• The measurement was temporarily impossible, therefore the totalizer value can be wrong.
