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Appendix
A.4 Flowrate Calibration and Calibration Tables
FUP1010 IP67 Portable
154
Operating Instructions, 03/2012, A5E02951522-02
Calibration Tables 1 through 3
SITRANS F 1010 instruments offer a unique methodology by which a particular flow
response of an instrument may be linearized or optimized by tabulating the results of a
series of calibration exercises or collected batch data points. Basically, the flow meter allows
the user to select any of a wide variety of system variables (flow rate, pressure, viscosity,
etc.) as a pointer into a table of calibration factors (up to 32). As the system variable is
updated, the value of the table’s output factors (or positive and negative flow) is re-evaluated
and used as a modifier for the current rate register. Note that the flow register is still zeroed
and Reynolds number compensated normally and these slope corrections are in addition to
these fundamentals.
Note
Kc is still active when this method is being used.
To install a Calibration table:
1. The user selects a system variable that appears to correlate strongly with calibration
shifts observed.
2. A table of values is formed comprised of the values that this index could assume over the
range of system operation. Remember, the tables created do not extrapolate beyond their
end points, they "clip."
3. A calibration factor, a number usually close to 1.00, is entered as a positive and a
negative flow rate correction factor (termed PosFlow Corr and NegFlow Corr) for each of
the desired index points.
The table may contain up to 32 pairs of these slope correction factors. Note that the Kc
factor, unlike these slope correction factors, is entered as a signed percent change in rate,
while these factors are simply rate multipliers. As points are entered, the point editor will
provide list access to the already entered points plus access to the [New Point] menu cell,
used to add a new point. The table may be created in its entirety and then activated by
selecting [Yes] in the [Table Active] menu cell. The entire table may be cleared by selecting
[Yes] in the [Clear Table] menu cell.
Note
Careless use of the calibration tables can have a detrimental impact on the measurement
performance of the flow meter.
Note
Take precautions before enabling these calibration tables. Although it is unlikely that all three
tables would ever be employed in a real installation, three tables are offered for maximum
user flexibility. Since the tables can be disabled without being destroyed, 2 or 3 optimization
strategies may be tested by this means in order to determine which approach is most
effective.