Siemens SITRANS FUH1010PVDX, Руководство по эксплуатации, Страница: 156 / 308

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CQO:1010PVXFM-3 Section 5
Calibration Tables 1 through 3
FUH1010PVX instruments offer a unique methodology by which a particular flow response of an instru-
ment may be linearized or optimized by tabulating the results of a series of calibration exercises or
collected batch data points. In essence, the meter allows the user to select any of a wide variety of
system variables (flowrate, 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 facility is being used.
To install a Calibration Table, proceed as follows:.
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 flowrate
correction factor (termed PosFlow Corr and NegFlow Corr) for each of the desired index points.
Kc Factor
To obtain the Kc factor, compare flow total data taken simultaneously from the flowmeter and a refer-
ence 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 loca-
tions. Compare outputs of the two totalizers to determine percentage increase (+) or decrease (-) that is
necessary to produce the best average correlation between the FUH1010PVX and the reference stan-
dard.
Selecting the Kc Factor
When the [Kc] menu cell is selected, the meter imposes this % slope adjustment of its rate output.
Output data is zeroed and corrected for the Reynolds number (flow profile compensated), however, in
addition, a percent change in the rate output is imposed based on the data entered in this cell. The
number entered by the user is evaluated into a slope correction factor by dividing it by 100 and algebra-
ically adding it to 1. The resulting factor is used as a multiplier on the rate register of the instrument. Thus
an entry of -3% will multiply the rate register by 0.97, for example.
To calculate Kc:
Kc =
x 100
Actual Rate
Indicated Rate -1
Kc = x 100
To enter the Kc Factor:
To enable numeric entry press .
Use the numeric keys to type 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 calibrated value.
To store the data press . 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.
ENT