Sensia CamCor CC001, Hardware User Manual

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CamCor CT and PRO Series Hardware Manual
107
Section 8
GAS MIXED FLOW (SLUG FLOW) ALARM FUNCTION
The Gas Mixed Flow Alarm Function, or “Slug Flow Alarm,” makes it possible to accurately measure flow, even when
large amounts of gas are mixed with the process fluid. The Slug Flow Alarm detects gases entrapped in the fluid, returns a
slug flow alarm, clamps the flow signal at “0” and produces a status output of the alarm event.
Configuring a Slug Flow Alarm
1. Set the slug flow lower limit density (see Transition Chart 2, page 70 , No. 2-2-3). When the device detects a density
lower than the established limit, the sensor interprets the reading as slug flow and analysis begins. Set a value smaller
than the expected flow density.
2. Set the slug flow higher limit density (see Transition Chart 2, page 70 , No. 2-2-4). When the device detects a density
higher than the established limit, the sensor interprets the reading as an error and analysis begins. Set a value greater
than the expected flow density.
3. Set the slug flow duration (see Transition Chart 2, page 70 , No. 2-2-5), which is the time required for the sensor to
identify flow outside the slug flow high/low limit and to issue a slug flow alarm (in seconds). The most recent mea -
sured value is returned until the user-established slug flow duration expires. Upon expiration of the slug flow duration,
the flow rate will be reported as “0.”
Assigning the Slug Flow Alarm to a Status Output
To assign the slug flow alarm to the status output function, configure the status output as follows. For more information, see
Status Output Function, page 102 .
1. Set “Error Status” as the status output function assignment (see Transition Chart 4, page 74 , No. 2-4-5-1).
2. Set the slug flow error selection to “On” (see Transition Chart 4, page 74 , No. 2-4-5-2-7).
3. Set the active output to “Off Active” or “On Active.” See Transition Chart 4, page 74 , No. 2-4-5-3 for more
information.
Slug Flow Alarm Example
• Slug flow lower limit density: 0.5 g/mL
• Slug flow higher limit density: 2.0 g/mL
• Slug flow duration: 10 sec.
Time
Time
Higher-limit density (2.0)
Lower-limit density (0.5)
Slug flow
alarm active
Slug flow
under
test
Slug flow
alarm active
Slug flow
under
test
Density
2.0
0.5
0
0
Slug flow identification time
(10 sec)
Flow rate (slug flow alarm active)
Flow rate (slug flow alarm inactive)
Density fell below
high limit value;
slug flow test
starts with flow
data retained.
Alarm canceled
as density
exceeded low
limit value.
Density fell below low limit value;
as slug flow test duration expires,
a slug flow alarm is issued with
flowrate clamped at 0.
Density exceeded high limit value;
as slug flow test duration expires,
a slug flow alarm is issued with
flowrate clamped at 0.
Density exceeded
high limit value;
slug flow test
starts with flow
data retained.
Alarm canceled
as density fell
below high limit
value.
Density (g/ml)
Flow rate (kg/min)
Slug flow identification time
(10 sec)
Figure 8.27—Slug flow alarm graph