User Manual

Commissioning
SmartRadar FlexLine Part No.: 4417.762_Rev07
6 - 110 Service Manual
The PV of the P3 pressure HART device is read and converted into SI
Units Pascals (Pa) within the FlexConn function PV.
The value is filtered, and the filtering factor depends on the value set in
the entity
[P3 Integration time]. A higher value gives more filtering, and a
lower value gives less filtering.
The correction factor stored in the
[P3 PV offset] entity is then subtracted
from the filtered value. If the
[P3 PV offset] entity = 0 no offset is applied.
Depending on the [PV selected type] entity, the P3 pressure can be
displayed as either absolute pressure or relative pressure.
TABLE 6-6 P3 pressure displayed unit types
If Relative pressure is selected, the value stored in the
[Ambient Air
Pressure]
entity is added to the measured pressure. If Absolute pressure
is selected, no factor is added. The final result is available in the
[Primary
Value]
entity.
NOTE: Absolute pressure is used in the density calculation;
the relative pressure is only displayed in P3
[Primary
Value]
.
For the FCI-HT software to differentiate between a HART device
malfunction and a HART device not actually installed, P3 pressure has
the entity
[P3 Installed] which must be set to either <Installed> if a P3
pressure HART device is actually fitted or
<Not Installed> if a P3 pressure
HART device is not actually fitted. For example, in the case of free-
venting tanks, P3 would usually not be installed.
If the P3 pressure status is
<Good Actual>, the P3 pressure value is also
stored in memory in the
[Last Valid P3] entity, to allow recovery from a
power-down situation when a P3 pressure is not available.
If the measured P3 pressure is invalid (e.g. HART scan error), the
software will check the
[P3 Installed] entity to determine if P3 is actually
fitted. If P3 is fitted, the software will check for a
[Manual P3 Pressure] entity
value to be entered. If no manual P3 pressure value is entered, the
[Last
Valid P3]
is used in the density calculation. If no [Last Valid P3] is available,
an error will be reported.
If P3 pressure is not installed - in the case of free-venting tanks - a
default value of 0.0 for P3 pressure is used for density calculations.
PV Unit Type Display Unit Type PV selected type
P3 Pressure Absolute 1
Relative 2