MODEL | SECTION 7.0 |
| PROGRAMMING |
7.6 SETUP CUST
The Model
Best results will be obtained by selecting data points that are representative of the typical operating range and are at least 5% different conductivity values. Plotting the graph of con- ductivity vs. concentration for the data points of interest before using this procedure is highly recommended. This will insure that unsuitable points (i.e. two concentrations with the same conductivity) and critical points (that best describe the curve) can be determined. All data points should be either on the rising side of the conductivity versus concentration curve or the falling side, but not both (i.e. both side of the conductivity maximum or minimum). Following these guideline will simplify the data entry procedure and provide optimum results.
U!SHI!!$'c"
>PLUT µ<µ
PVO!RUT!!%
µ<!#µ
/QPG!#!!"c"""
The first point entered "COnd 1"should be at the normal operating condition. Other points, |
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µµ<!$!!"c""" | |||||||
both above and below "COnd 1" can then be entered. Very nonlinear conductivity curves may | |||||||
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need additional points to characterize these regions. Do not use the same data for more than |
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one point and only use real data - do not interpolate. |
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/QPG!$!!"c""" | |||||||
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| NOTE |
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| µµ<!%!!"c""" | |||
| The default values for the custom curve are three data points, reference tempera- | ||||||
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| ture of 25°C and a linear temperature slope of 2%/°C. This combination will yield |
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| the best results in most applications. If normal operation is over 40°C or under |
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| /QPG!%!!"c""" | ||||||
| 10°C, the reference temperature should be changed to the normal process tem- |
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| perature. If the temperature slope at the reference temperature is known, it can be |
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| used. |
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| /DNF!/QPG | ||
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7.6.1 Procedure |
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| 1. From the main menu, press PROG; then press NEXT four times. SetUP CuSt will | |||||
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PROGRAM | |||||||
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U!SHI |
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| 2. Press ENTER. t rEF will appear. If needed, change the reference temperature from | ||||
EXIT | NEXT ENTER |
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| the factory default 25°C (77°F) to a different reference temperature for the process. | |||||
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| Press ENTER. |
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PROGRAM
>P5U
EXIT NEXT ENTER
3.UnIt will appear. Press or to select the desired measurement units: µS (micro- Siemens), nS (milliSiemens), none (no units displayed), % (percent), or ppn (parts per million); then press ENTER.
PROGRAM
8VO!:UT
EXIT NEXT ENTER
PROGRAM
/DNF!/VTU
EXIT NEXT ENTER
4.NUM PtS will appear. Press or to select the desired number of data points for a custom conductivity curve. Selecting 2 will generate a linear relationship for conductiv- ity and concentration at the given reference temperature.
a.Enter the concentration for Pt. 1 (displayed as µS 1). Press ENTER.
b.Enter the known conductivity for Pt. 1 in µS/cm. Press ENTER.
c.Complete this process for additional known data points. Press ENTER.
5.CALC Cust will appear. Press ENTER. PrOCESSinG will appear briefly; then APPLY CUSt will appear. Press ENTER to enter the custom curve into memory and return to the SetUP CuSt screen.
The Custom curve will now be used to display and output all conductivity (or resistivity) measurements if Cust is selected in the Display menu for measurement type.
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