28
INVUE CR288 CONCENTRATION MONITOR
Installation and Use Manual | Entegris, Inc.
7. Press
2nd Order Regression Fit
to calculate a
second order coefficient, FTCC2.
This is useful in processes characterized by large
temperature variations FTCC2. If the temperature
varies over a significant range (process depen-
dent), invoking the second order term allows the
software to incorporate a non-linear temperature
behavior.
This coefficient is very dependent on the data set
used to develop it. The data used to develop the
coefficient should have a temperature range
equal to or greater than the range the sensor sees
in use. The user must determine if using FTCC2 is
appropriate for their system.
8. Press
Regression Fit
under FTCC3 to calculate a
third coefficient, FTCC3. This is a derivative term
that is useful in processes with rapid temperature
variations FTCC3. Rapid changes in temperature
may not register immediately due to the response
of the onboard temperature sensor. FTCC3
compensates for these time delays by factoring
the time rate of change of the temperature into
the compensation algorithm.
NOTE: Use FTCC3 only when FTCC1 and FTCC2
do not compensate adequately. Including this term
dramatically increases the noise values.
9. Press
Optimize All
to have the graph perform the
best mathematical least-squares fit using all three
coefficients. Manually adjust coefficients using the
up and down arrows on the screen or by entering
new values.
10. Press
Save Newly Compensated Dat
a. The data
log files contain the calculated temperature
compensation coefficient and also reflect the
new IoR@20 values.
11. Press
Update Sensor on Px to New TCC
(where
x = the port number in use) to apply the tempera-
ture compensation to the data graph tab display.
The software returns to the Sensor Calibration tab
with the calculated Fluid Temp Compensation
Coeff added to the Sensor Info table.
12. Press
Exit Without Saving
to exit the wizard and
not apply the temperature compensated index of
refraction to the data graph display.
13. Save the temperature compensation value either
by pressing
Update Sensor to New TCC
or by
entering it manually into the Sensor Info tab.
14. Re-zero the sensor with DIW.
INFORMATION FOR 4-20 MA APPLICATIONS
Table 2. Equation to translate signal output to
concentration and temperature
Concentration (%) = (mA
–
4) / 16 * (C
20ma
–
C
4ma
) + C
4ma
Temperature (°C) = (mA
–
4) / 16 * (T
20ma
–
T
4ma
) + T
4ma
where:
C
4ma
= AO Range: Lowest concentration (%) = 4 mA
C
20ma
= AO Range: Highest concentration (%) = 20 mA
T
4ma
= AO Range: Lowest concentration (
°C
) = 4 mA
T
20ma
= AO Range: Highest concentration (
°C
) = 20 mA
If the sensor has never been used or changed,
the values are at the factory defaults. See Table 3.
Factory Default mA Settings for Concentration
and Temperature.
Table 3. Factory default mA settings for
concentration and temperature
Concentration corresponding
to 4 mA
-1.00%
Concentration corresponding
to 20 mA
30.00%
Temperature corresponding
to 4 mA
10°C (50°F)
Temperature corresponding
to 20 mA
65°C (149°F)