Zero Point Adjustment - Siemens SITRANS FC430 Operating Instructions Manual

Functions

8.2 Zero point adjustment

Reference density is the density of the media at reference conditions, normally
2)
atmospheric pressure and 20 °C. Reference density can be programmed into the flowmeter
menu in two forms, either as a fixed reference or with a selection of linear or square-law
temperature dependence. The choice of fixed or calculated reference density and of linear or
square-law temperature dependency is according to the application and user preferences.
The customer-specified density/temperature tables may be derived from the mass fraction
3)
or volume fraction of any two-part mixture. Fraction calculations are naturally performed in
the ratio provided, or in mass ratio when using the built-in tables. Volume or mass ratios
derived from the fraction table are calculated through the composite media density.
8.2 Zero point adjustment
In the following the automatic zero point adjustment function is described. For further details,
see the appendix Zero point adjustment (Page 379).
Note
Preconditions
Before a zero point adjustment is initiated, the pipe must be flushed, filled and at an absolute
flowrate of zero preferably also at operating pressure and temperature. Refer to "Zero point
adjustment" via HMI (Page 76) or PDM (Page 105) for more details.
Note
Change of parameters during zero point adjustment
Do not change any other parameter during the zero point adjustment procedure.
Automatic zero point adjustment
The device measures and calculates the correct zero point automatically.
The automatic zero point adjustment of the flowmeter is set by the following parameters:
● Duration
● Start Zero Point Adjustment
When zero adjust is initiated by selecting "Start Zero Point Adjustment", the massflow values
are acquired and totalized for the configured period (Duration). The default zero point
adjustment period (30 s.) is normally sufficient for a stable zero point measurement.
Note
Extremely low flow quantity
If the flow quantity is extremely small, extremely precise measurement is necessary. In this
case, a long zero point adjustment period can be selected for improved zero point
adjustment.
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Operating Instructions, 05/2015, A5E03361511-AF
FC430 with HART