The parameter Zero Point Standard Deviation is located in the Maintenance & Diagnostics
menu in the SIMATIC PDM.
• The error curve is plotted from the formula:
E = ± (Cal)
2
+
z x 100
qm
( )
2
E
= Error [%]
Z
= Zero point [kg/h]
qm = Mass flow [kg/h]
Cal. = Calibrated flow accuracy: 0.10
FSO (sensors
max. flow rate)
Error in % of actual mass flow rate with 95% confidence
(probability)
Actual mass
flow rate
-1.0
-0.5
1.0
0.5
0.15
-0.15
50%
25%
5%
75%
100%
Table 10-1
Reference conditions for flow calibrations (ISO 9104 and DIN/EN 29104)
Flow conditions Fully developed flow profile
Temperature,
medium
20 °C ± 2 °C (68 °F ± 3.6 °F)
Temperature,
ambient
20 °C ± 2 °C (68 °F ± 3.6 °F)
Liquid pressure
2 ± 1 bar
Density
0.997 g/cm3
Supply voltage
Un ± 1 %
Warming-up
time
30 min.
Cable length
5 m between transmitter and sensor
10.3.2.4
Step 4: Improving the application
In the following it is described how to find the causes of a high Zero point standard deviation and
how to improve the installation.
Setting Low flow cut-off
In order to see if the zero point becomes more stable when making changes / adjustments, the
Low Mass flow cut-off (MassFlowCutOff) must be set to 0.0 kg/s.
When Low flow cut-off has been set, it is possible to see the instability directly from the mass
flow in the online window ("View → Process variables")
Diagnostics and troubleshooting FCT010
10.3 Operation troubleshooting
SITRANS MASS 2100 & FC300 (FCT010/DSL)
Operating Instructions, 06/2020, A5E39788682-AB
103