Siemens SITRANS F Series Operating Instructions Manual page 129

4. Press the <Right Arrow> again and use the keypad keys to enter the required Kc factor
5. To store the data press <ENTER>. Note that Kc now appears in the [Calib. Flowrate]
MultiPoint Calibration
MultiPoint calibration serves applications that require a non-linear meter calibration. You can
enter correction factors for up to ten significant points over the entire measurement range.
This is accomplished by:
● Selecting up to 10 separate calibration points by entering a raw (un-calibrated) flow rate.
● Entering a negative or positive correction for each calibration point that you select.
Like the Kc slope correction described previously, you locate critical flow rate points by
comparing flow total data taken simultaneously from the flow meter and a reference meter
whose accuracy meets the required standard. Again, it is important to note that you must
allow both meters to accumulate flow total data for long enough to average out any
differences due to flow fluctuation between the meter locations.
Compare the two flow total readings to identify up to ten separate points (termed raw flow
rates) where there are significant deviations between flow meter and the reference meter.
Calculate correction factors (either negative or positive percentages) for up to ten points
along the flow range. For example, entering [-0.1] for point 1 produces a negative 0.1%
change in the meter output whenever the system measures the raw flow rate specified for
point 1, etc. The valid range for each percent correction is from -50% to +50%. If you enter a
value outside of this range, the flow meter will set the calibration factor to the nearest limit.
Use these to match the output of the flow meter with the response curve of the reference
meter. Selected calibration points must increase in magnitude from point 1 to point 10 (or the
last point that you want to calibrate).
Note
Raw flow rates must be entered in ascending order.
To perform a MultiPoint calibration:
1. From the [Meter Type] menu press the <Right Arrow> key and then <ENTER>.
2. Scroll down to the [Span/Set /Cal] menu, press the <Right Arrow> key and scroll down to
3. Press the <Right Arrow> key and scroll to [Multipoint].
FST020 IP65 NEMA 4X
Operating Instructions, 02/2012, A5E03086487-05
(as calculated above). Note that the Kc value can be negative or positive. Enter the - or +
sign first and then enter the calibrated value.
menu cell with its new value. Also note that this Kc value can be viewed on the site
printout.
[Calib. Flowrate].
Appendix
A.4 Flowrate Calibration
127