16 Advanced functions
16.4 Upper limit of the flow velocity
FLUXUS F808
2020-06-25, UMFLUXUS_F808V2-2EN
130
16.4
Upper limit of the flow velocity
Single outliers caused by heavily disturbed surroundings can appear among the measured values of the flow velocity. If
these outliers are not ignored, they will affect all derived physical quantities, which will be unsuitable for the integration
(e.g., pulse outputs).
It is possible to ignore all measured flow velocities exceeding the preset upper limit. These measured values will be
marked as outliers.
The upper limit of the flow velocity is set in
Special Funct.\SYSTEM settings\Measuring\Velocity limit
.
• Enter zero to switch off the outliers check.
• Enter a limit > 0 to switch on the outliers check. The measured flow velocity will then be compared to the entered upper
limit.
• Press ENTER.
If the flow velocity is higher than the upper limit,
• the flow velocity will be marked as invalid. The physical quantity cannot be determined.
• the LED of the measuring channel will light red
• a (!) will be displayed after the unit of measurement (in case of a normal error (
?
) is displayed).
16.5
Cut-off flow
The cut-off flow is a lower limit for the flow velocity. All measured flow velocities that are lower than the limit and their de
-
rived quantities are set to zero.
The cut-off flow can depend on the flow direction. The cut-off flow is set in
Special Funct.\SYSTEM settings\Mea
-
suring\Cut-off Flow
.
• Select
sign
to define a cut-off flow depending on the flow direction. One limit is set for the positive and negative flow ve
-
locity.
• Select
absolut
to define a cut-off flow independent of the flow direction. A limit is set for the absolute value of the flow
velocity.
• Press ENTER.
• Select
factory
to use the default limit of 2.5 cm/s (0.025 m/s) for the cut-off flow.
• Select
user
to enter the cut-off flow.
• Press ENTER.
If
Cut-off Flow\sign
and
user
are selected, 2 values have to be entered:
Example
TT-Failed
NoiseTrek: After 40s
NT-Failed
TransTime: After 60s
NT-Ok,but check TT: Each 300s
Keep TT checking: For 5s
If no measurement is possible in the TransitTime mode within 40 s, the transmitter toggles to the NoiseTrek mode. If no
measurement is possible in the NoiseTrek mode within 60 s, the transmitter toggles back to the TransitTime mode.
If valid measured values are obtained during the measurement in the NoiseTrek mode, the transmitter toggles to the
TransitTime mode every 300 s. If no measurement is possible in the TransitTime mode for the duration of 5 s, the trans
-
mitter toggles back to the NoiseTrek mode. If a valid measured value is obtained in the TransitTime mode within 5 s, the
transmitter continues the measurement in the TransitTime mode.
Special Funct.\SYSTEM settings\Measuring\Velocity limit
Notice!
If the upper limit is too low, a measurement might be impossible because most of the measured values will be marked
as invalid.
Special Funct.\SYSTEM settings\Measuring\Cut-off Flow