RKI Instruments 35-3001-09 - Manual (Page 23)

35-3001-09 Oxygen/Hydrogen Sulfide Sample-Draw Detector • 19
If an application is very demanding, for example if the environment is not well controlled, then
more frequent calibration than every 3 months may be necessary.
Calibration, Oxygen Sensor
This section describes how to calibrate the oxygen sensor in the sample-draw detector. It includes
procedures to prepare for calibration, set the fresh air reading, set the zero reading, and return to
normal operation.
NOTE: Calibrating the sample draw detector may cause alarms. Be sure to put the controller into
its calibration program or disable external alarms before continuing.
NOTE: This procedure describes calibration using a demand flow regulator.
Preparing for Calibration
NOTE: If you can verify a fresh air environment, it is not necessary to use a zero air calibrating
sample to set the fresh air reading at the controller.
1. Follow the instructions in the controller’s operator’s manual for entering calibration mode.
2. Screw the regulator into the zero air calibration cylinder.
Setting the Fresh Air Reading
1. Connect the sample tubing from the demand flow regulator to the sample-draw detector’s inlet
fitting. This step is not necessary if you verified a fresh air environment earlier in this
procedure.
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 fresh air reading.
4. Disconnect the sample tubing from the inlet fitting.
5. Unscrew the regulator from the zero air calibration cylinder.
Setting the Zero Reading
1. Screw the demand flow regulator onto the 100% N
2
calibration cylinder.
NOTE: If you do not want to keep two calibration cylinders, 100% N
2
and 25 ppm H
2
S in
nitrogen, you may use the 25 ppm H
2
S in nitrogen to zero the oxygen sensor.
2. Connect the sample tubing from the regulator to the inlet line.
3. Allow the sample-draw detector to draw the calibrating sample for 1 minute.
4. Follow the directions in the controller’s operator’s manual for setting the zero (oxygen free)
reading.
5. Disconnect the sample tubing from the sample-draw detector’s inlet fitting.
6. Reconnect the incoming sample line to the inlet fitting.
7. Unscrew the regulator from the calibration cylinder.