MANUALP/4000_SERVICE_0712 July2012
20
Notes on Calibration Procedures for THERMAL CONDUCTIVITY Sensors
• The CO
2
SET POINT can be left as it is for the duration of the AUTO-CAL
and MAN-CAL calibration sequences. Once the CO
2
display has stopped
flashing the controller will adjust the workspace CO
2
level to the SET POINT.
• AUTO-CAL is best done last thing at night as the calibration usually takes
from 1 to 4 hours to complete.
• CONTHERM recommends that AUTO-CAL is carried out at least every two
months OR if a Temperature Calibration has taken place.
CO
2
CALIBRATION – INFRA-RED CO
2
SENSOR (IR)
There are two modes of calibration for the INFRA-RED CO
2
system. A USER-
CALIBRATION and FACTORY CALIBRATION. Use the user calibration for
small calibration adjustment and can be carried out via the front panel buttons.
The factory calibration is used when the user calibration can not obtain the
correct result and when the sensor is replaced and is carried out by qualified
service personnel. Both require the enclosure to be stabilised at the desired set
Temperature. A detailed IR calibration procedure can be found on Servicing
Section.
USER IR CO
2
CALIBRATION
This is used for small calibration adjustments (approx ±0.5%) and may be
carried out by the user via the front panel buttons.
Press and hold the CO
2
button until the display momentarily blanks, this will
access the SET POINT mode and the SET LED above the temperature display
will be on.
Press both TEMP and CO
2
buttons at the same time. The temperature display
will show [Cal] for 2-3 seconds and then show the current co
2
reading.
Adjust the value displayed to read the same as your reference co
2
monitoring
device.
When exiting the user calibration routine a calibration constant (0.0 to 3.2) will
be displayed, this number should be noted down.
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