Sampling For Vc Multichannel: An Advanced Calibration - Satron Instruments VC Quick Start Manual

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Sampling for VC Multichannel: An Advanced Calibration

Unlike consistency, the best calibration of the VC multichannel requires much more complex analysis and
close coordination of transmitter information to the exact time that the sample is extracted from the
process. There are two output channels in the VC multichannel, one for Consistency of the stock and the
other for the specific parameter being measured. Kappa, Ash, Freeness. Brightness etc. must be carefully
determined in the laboratory and the results correlated to the transmitters measured variables. The result is
that the parameters measured and displayed on the second channel are non-linear in nature and the
calibration is significantly more complex to accomplish. Therefore, more process analysis data is needed to
complete these calibrations. It is recommended that twenty-five to thirty samples and lab analyses must be
collected for the calibration purposes.
The same range of operation applies; the samples need to cover at least fifty percent of the operating range
of the variable. The same two-person data collection procedure should be followed. The key to accurate
results is to correctly record the date and time stamp when the sample is taken. The external sampling
switch helps to improve the accuracy of the sampling and time stamping that is necessary for good results.
Once the data is collected, a multi-variable polynomial regression analysis is performed to determine the
unique calibration curve for each application. The transmitter uses a linear equation in three variables as
the calibration curve for the application.
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Transmitter asks you to enter first calibration data point. Use the
UP/DOWN arrows to move to the corresponding sample and press ENTER.
You can also use the water point stored inside the transmitter as the first
calibration point (SAMPLH2O).
An OK message shortly appears in the display followed by the request to
enter next data point and next sample item will appear in the display. Use
UP/DOWN arrows to select second calibration point and press the ENTER.
New gain and offset values will scroll through the display. When SAVE?
appears in the display, press ENTER to accept or ESC to exit without
saving.
An OK message will appear in and the display will automatically return to
the Calibrate sub-menu. Press the ESC key until the PV reading in the
main menu is displayed