Interface Measurements With Fully Immersed Probes - Emerson Rosemount 3300 Series Reference Manual

Rosemount 3300 Series
Interface measurements
with fully immersed
probes
Figure 6-6. Interface Level
measurements in a full bridle
pipe.
6-8
The 3300 series has a measurement option which makes it possible to handle
interface measurements when the product level is not visible, for example in a
full bridle pipe as illustrated in Figure 6-6. In this case the probe is fully
immersed into the upper product, and only the interface level is detected by
the transmitter. Even if the upper product level drops, it is ignored by the
transmitter which continues to measure only the interface level, but the
measurement accuracy is reduced since the transmitter does not take into
account the influence of the air gap above the product surface.
The Measurement Mode parameter is available via the
HART command [1, 3, 9]. Choose the Interface when Immersed Probe option.
Measurement mode Interface when Immersed Probe can also be activated in
the RCT software:
1. Open the Setup window.
2. Select the Tank Config tab.
3. Choose Measurement Mode Interface when Immersed Probe.
4. Click the Send Page button.
NOTE!
Do not use Measurement Mode Interface when Immersed Probe in "standard"
applications when both Interface Level and Product Level are measured.
If the product level drops, the air filled region in the upper part of the pipe will
slightly reduce the measurement accuracy of the interface level. To achieve
high accuracy in this measuement mode the probe must be fully immersed.
Interface Distance
Interface Level
NOTE!
Adjust Threshold T2 if the level pulse is not detected.
Reference Manual
00809-0100-4811, Rev AB
July 2003
Product Level
is ignored
Interface Level is
measured