26 • 35-3001A-10 Oxygen/Carbon Monoxide Sample-Draw Detector
4. If necessary, use a small flat-blade screwdriver to adjust the span potentiometer until the voltmeter
reading is 434 mV (± 2 mV). If you used a zero air calibration cylinder to set the zero reading,
proceed to step 5. If you verified a fresh air environment, proceed to the next 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.
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.
