Emerson Micro Motion LNG Series, Configuration And Use Manual

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Values below this will cause the transmitter to post Alert A105 ( Slug Flow.
Tip
Gas entrainment can cause your process density to drop temporarily. To reduce the
occurrence of two-phase flow alerts that are not significant to your process, set
Two-Phase Flow
Low Limit
slightly below your expected lowest process density.
You must enter
Two-Phase Flow Low Limit
in g/cm ³ , even if you configured another unit
for density measurement.
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 ( Slug 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/cm
³
, even if you configured another
unit for density measurement.
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.
• All outputs that are configured to represent flow rate hold their 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:
• Outputs that represent flow rate revert to reporting actual flow.
Configure process measurement
32 Micro Motion ® LNG Series Meters