Zero Point Adjustment - Siemens SITRANS FC430 Operating Instructions Manual

Functions

8.2 Zero point adjustment

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.
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 or PDM 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.
Zero point calculation
During zero point adjustment, an average value is automatically calculated from a large number
of samples. The resultant flow value represents an offset from true zero flow. The standard
deviation is also calculated which represents the stability of the zero offset value.
Successful automatic zero point adjustment
If the new zero point offset value is valid, it is automatically stored as the new zero point for
the sensor. It remains stored in the case of a power failure.
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FC430 (From firmware 4.0)
Operating Instructions, 06/2017, A5E39789392-AA