You must enter Two-Phase Flow Low Limit in g/cm³, even if you configured another unit
for density measurement.
The default value for Two-Phase Flow Low Limit is 0.0 g/cm³. The range is 0.0 to
3.0 g/cm³.
2. Set Two-Phase Flow High Limit to the highest density value that is considered normal in
your process.
Values above this will cause the transmitter to post Alert A105 (Two-Phase Flow).
Tip
To reduce the occurrence of two-phase flow alerts that are not significant to your process, set
Two-Phase Flow High Limit slightly above your expected highest process density.
You must enter Two-Phase Flow High Limit in g/cm³, even if you configured another
unit for density measurement.
The default value for Two-Phase Flow Low Limit is 3.0 g/cm³. The range is 0.0 to
3.0 g/cm³.
3. Set Two-Phase Flow Timeout to the number of seconds that the transmitter will wait for
a two-phase flow condition to clear before posting the alert.
The default value for Two-Phase Flow Timeout is 0.0 seconds, meaning that the alert
will be posted immediately. The range is 0.0 to 60.0 seconds.
Detecting and reporting two-phase flow
Two-phase flow (gas in a liquid process or liquid in a gas process) can cause a variety of
process control issues. By configuring the two-phase flow parameters appropriately for
your application, you can detect process conditions that require correction.
Tip
To decrease the occurrence of two-phase flow alerts, lower Two-Phase Flow Low Limit or raise Two-Phase
Flow High Limit.
A two-phase flow condition occurs whenever the measured density goes below Two-Phase
Flow Low Limit or above Two-Phase Flow High Limit. If this occurs:
• A two-phase flow alert is posted to the active alert log.
• Line density is held at its last pre‐alert value for the number of seconds configured in
Two-Phase Flow Timeout.
If the two-phase flow condition clears before Two-Phase Flow Timeout expires:
• Line density reverts to actual process density.
• The two-phase flow alert is deactivated, but remains in the active alert log until it is
acknowledged.
If the two-phase flow condition does not clear before Two-Phase Flow Timeout expires, line
density reverts to actual process density, but the two-phase flow alert remains active.
Configure process measurement
Configuration and Use Manual 27
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