35-3001-13-02 Carbon Dioxide/Oxygen Sample-Draw Detector • 21
3. Push the tubing stub up and out of the front ferrule being careful not to lose the ferrule set. If you do lose the
ferrule set or if it is damaged, see “Parts List” on page 24 for the spare part numbers.
4. Push the new tubing up through the inlet fitting tube nut and replace the ferrule set and the O-ring, if it came
out, in the orientation shown in Figure 5.
5. Screw the inlet fitting tube nut back onto the fitting body. See “Connecting the Sample Lines to the Sample-
Draw Detector” on page 12 for instructions to install a new piece of tubing into the fitting.
Calibration Frequency
Although there is no particular calibration frequency that is correct for all applications, a calibration frequency of
every 3 months is adequate for most sample draw detector applications. Unless experience in a particular
application dictates otherwise, RKI Instruments, Inc. recommends a calibration frequency of every 3 months for
the oxygen detector and every 6 months for the infrared CO
2
detector.
If an application is not very demanding, for example detection in a clean, temperature controlled environment,
and calibration adjustments are minimal at calibration, then a calibration frequency of every 6 months is
adequate for the oxygen detector and every 9 to 12 months is adequate for the infrared CO
2
detector.
If an application is very demanding, for example if the environment is not well controlled, then more frequent
calibration than every 3 months for the oxygen detector and every 6 months for the infrared CO
2
detector may be
necessary.
Calibration, IR CO
2
Sensor
This section describes how to calibrate the IR CO
2
sensor. It includes procedures to prepare for calibration, set
the zero reading, set the response reading, and return to normal operation.
NOTE:
This procedure describes calibration using a demand flow regulator.
Preparing for Calibration
1. Follow the instructions in the controller’s operator’s manual for entering calibration mode.
Setting the Zero Reading
Since there is a background of CO
2
in air of typically 300 - 600 ppm (0.03 - 0.06% volume), it is necessary to use
a calibration kit with a 100% nitrogen cylinder to set the zero signal for the 0 - 5,000 ppm and 0 - 5% volume
versions. Fresh air can be used to set the zero signal for the 0 - 50% and 0 - 100% volume versions.
1. Connect the sample tubing from the demand flow regulator to the sample-draw detector’s inlet line.
2. Allow the sample-draw detector to draw sample for one minute.
3. Follow the directions in the controller’s operator’s manual for setting the zero reading.
4. Disconnect the sample tubing from the inlet line.
5. Unscrew the regulator from the 100% nitrogen calibration cylinder.
Setting the Response Reading
1. Screw the regulator into the carbon dioxide calibration cylinder.
2. Connect the sample tubing from the demand flow regulator to the sample-draw detector’s inlet line.
3. Allow the sample-draw detector to draw sample for one minute.
