26 • 35-3010A-13 Sample-Draw Detector
Calibration, Oxygen Detector
This section describes how to calibrate the oxygen detector in the sample-draw detector. It includes
procedures to prepare for calibration, set the zero reading, set the fresh air reading, and return to
normal operation.
NOTE:
This procedure describes calibration using a demand flow regulator, a zero air calibration
cylinder, and a 100% nitrogen calibration cylinder to set the zero reading.
Preparing for Calibration
CAUTION:
This procedure may cause alarms at the controller. Take appropriate action to avoid this,
such as entering the calibration mode at the controller.
1. Open the housing door.
2. Set a voltmeter to measure in the millivolt (mV) range.
3. Plug the voltmeter into the test points on the oxygen transmitter. Plug the positive lead into the test
point labeled
TP+
; plug the negative lead into the test point labeled
TP-
.
Setting the Zero Reading
1. Screw the regulator into the 100% nitrogen calibration cylinder.
2. Connect the calibration kit sample tubing to the regulator.
3. Connect the sample tubing from the regulator to the inlet line at or near the sample-draw detector’s
INLET fitting.
4. Allow the sample-draw detector to respond to the calibrating sample for approximately 1 minute.
5. After one minute, check the mV output on the oxygen transmitter test points and verify a reading
of 100 mV (±2 mV).
6. If necessary, use the span pot on the transmitter to adjust the reading to 100 mV (± 2 mV).
7. Disconnect the sample tubing from the inlet line.
8. Unscrew the regulator from the 100% nitrogen calibration cylinder.
9. For convenience, leave the regulator attached to the sample tubing.
Setting the Fresh Air Reading
CAUTION:
This procedure may cause alarms at the controller. Take appropriate action to avoid this,
such as entering the calibration mode at the controller.
NOTE:
If you can verify a fresh air environment, it is not necessary to use the zero air calibration
cylinder to set the zero reading.
1. Screw the regulator into the zero air calibration cylinder.
2. Connect the calibration kit sample tubing to the regulator.
3. Connect the sample tubing from the regulator to the inlet line at or near the INLET fitting.
