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Reference Manual
00809-0100-4530, Rev BA
July 2009
C-7
Rosemount 5300 Series
Changing the Upper Null
Zone
Measurements are not performed within the Upper Null Zone (UNZ). By
setting the UNZ parameter to zero, measurements can be performed in the
region close to the flange (Near Zone).
If there are measurement problems in the upper part of the tank, you may use
the Trim Near Zone function as described above.
If the desired measurement range is below the Near Zone, or if disturbing
objects are located below the Near Zone, the Upper Null Zone parameter can
be used to avoid measurements above a certain level.
To set the Upper Null Zone with a 375 Field Communicator:
1. Select the HART command [2, 1, 2, 3].
2. Select the Upper Null Zone option.
3. Enter the desired value.
To set the Upper Null Zone with RRM:
1. Start RRM.
2. Click the Tank icon in the Device Config/Setup toolbar.
3. Select the Probe tab in the Tank window.
4. Type the desired value in the Upper Null Zone field.
5. Click the OK button. Now the Upper Null Zone is stored in the transmitter
memory.
Figure C-4. Upper Null Zone.
Figure C-5. Identifying the Upper
Null Zone in the Echo Curve plot
Reference Gauge Height
Upper Null
Zone
Product Level
Upper Reference Point
3.0
5.0
Upper Null Zone
Disturbance
Amplitude, mV
Distance, m