Siemens SITRANS FUS1020, Manual, Page: 166 / 251

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1020NFM-1D Section 6
6.7.3 CALIBRATE FLOWRATE
The 1020 intrinsic calibration is excellent as confirmed by numerous laboratory and field trials under
diverse application conditions. We thus can confidently say that in any given application, the majority
of conventional flowmeters can not match the system’s measurement range or its linearity. Some
applications may require an output adjustment to match an official external reference. The [Calibrate
Flowrate] menu allows you to select a calibration mode. The right-hand column shows the active
calibration mode. You can select Intrinsic (factory), Kc (Slope Correction) or Multipoint (Non-linear)
Calibration. Selecting either of the external calibration modes will not eliminate the Intrinsic (factory)
calibration. You can use this menu cell to switch between Intrinsic, Kc or Multipoint at any time.
Kc Calibration
For most applications, the measured flow range produces a linear meter response. Therefore, the Kc
(slope correction) calibration is the preferred method since it only requires a single correction factor
for all the flow rates encountered. Changing the calibration can cause profound changes in a flowmeter’s
operating characteristics. Use only the most respected flow standard to obtain a correction factor. The
percentage you enter must provide an accurate and consistent shift across the entire flow range
anticipated for the application.
To obtain the Kc factor, compare flow total data taken simultaneously from the 1020 and a reference
meter whose accuracy meets the required standard. Allow both meters to accumulate flow total data
long enough to average out any differences due to flow fluctuation between the two meter locations.
Compare outputs of the two totalizers to determine percent-age increase (+) or decrease (-) that is
necessary to produce the best average correlation between 1020 and the reference standard. For
example, entering [-0.29] will produce a reduction of 0.29% in the calibration at all flow rates.
Note:
always enter the + or - sign first.
To calculate Kc:
To enter the Kc Factor:
To enable numeric entry press the <Right Arrow>.
Use PC numeric keys or Keypad to enter the required Kc (as calculated above). Note that the
Kc value can be negative or positive. Enter the - or + sign first, then type in the calculated value.
To store the data press <ENTER> Note that Kc now appears in the right-hand column of the
Calibrate Flow Rate menu cell with its new value. Also note that this Kc value can be viewed on
the site printout.
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 accom-
plished by:
(a) Selecting up to 10 separate calibration points by entering a raw (un-calibrated) flow rate.
(b) Entering a negative or positive correction for each calibration point that you select.
Kc =
x 100
Actual Rate
Indicated Rate -1
Kc =
x 100