RKI Instruments 35-3001A-09 - Manual (Page 26)

22 • 35-3001A-09 Oxygen/Hydrogen Sulfide Sample-Draw Detector
section, Setting the Zero Reading.
5. Disconnect the sample tubing from the inlet fitting.
6. 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. Verify a voltmeter reading of 100 mV (± 2 mV).
5. If necessary, use the zero potentiometer on the amplifier to adjust the reading to 100 mV (± 2
mV).
6. Disconnect the sample tubing from the sample-draw detector’s inlet fitting.
7. Reconnect the incoming sample line to the inlet fitting.
8. Unscrew the regulator from the calibration cylinder.
Returning to Normal Operation
1. Wait 1 to 2 minutes to allow the oxygen reading at the controller to return to normal, then
return the controller to normal operation.
NOTE: If you do not allow the oxygen reading to return to normal, then unwanted alarms may
occur.
2. Remove the voltmeter leads from the amplifier test points.
3. Close the housing door.
4. Verify that the controller display reading stabilizes at 20.9%.
5. Store the components of the calibration kit in a safe and convenient place.
Calibration, H
2
S Sensor
This section describes how to calibrate the hydrogen sulfide sensor of the sample-draw detector. 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.
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.