Calibration For Gases; Process Conditions; Process Pressure Effect; Process Fluid Temperature Effect - Siemens SITRANS FC720 Operating Instructions Manual

Process conditions

8.9.2 Calibration for gases

Same calibration conditions described in Mass flow calibration and density adjustment
[} 34] apply for gas measurement according to AGA11 water calibration transferability
Specifications are determined based on evaluation at accredited ISO/IEC17025
calibration at following conditions:
Terms
Fluid
Fluid temperature
Process pressure
Different gases can be considered by entering characteristic gas sound velocity and
related temperature coefficient
Only with SITRANS FC HART firmware rev.4 or later. For details please contact your
1)
local Siemens sales organization.
8.10 Process conditions

8.10.1 Process pressure effect

Process pressure effect is defined as the change in sensor flow and density deviation due
to process pressure change away from 1barg reference condition. This effect can be
corrected by dynamic pressure input or a fixed process pressure.
Tab. 2: Process pressure effect, wetted parts stainless steel 1.4404/ 316L and Ni alloy C-22/
2.4602
Meter size
FCS700
DN100
FCS700
DN150
FCS700
DN200

8.10.2 Process fluid temperature effect

For mass flow and density measurement, process fluid temperature effect is defined as
the change in sensor flow and density accuracy due to process fluid temperature change
away from 20°C reference condition. For temperature ranges, see Process fluid
temperature range [} 37].
Temperature effect on Zero
Temperature effect on Zero of mass flow can be corrected by zeroing at the process fluid
temperature.
Temperature effect on mass flow
The process fluid temperature is measured and the temperature effect compensated.
However due to uncertainties in the compensation coefficients and in the temperature
measurement an uncertainty of this compensation is left. The typical rest error of
SITRANS FC temperature effect on mass flow is:
Reference conditions
Natural Gas
20 °C (68 °F)
16 barg (232 psig) and 50 barg (725 psig)
1) .
Material Deviation of Flow
in % of rate
per bar
1.4404/316L -0.0289
C-22/2.4602 -0.0313
1.4404/316L -0.0484
1.4404/316L -0.0183
A5E52748387-AA, 2023/09
Deviation of Density
in % of rate in g/l
per psi per bar
-0.00199 -0.140
-0.00216 -0.191
-0.00334 -0.179
-0.00126 -0.033
FC7x0
Accuracy
.
1)
in g/l
per psi
-0.0097
-0.0132
-0.0123
-0.0022
35 / 180