18 • 35-3001A-10 Oxygen/Carbon Monoxide Sample-Draw Detector
3. Set a voltmeter to measure in the millivolt (mV) range.
4. Plug the voltmeter leads into the test points on the oxygen amplifier. Plug the positive lead into the
red (+) test point; plug the negative lead into the black (-) test point.
5. Verify a voltmeter reading of 434 mV (± 2 mV).
6. If necessary, use a small flat-blade screwdriver to adjust the span potentiometer until the voltmeter
reading is 434 mV (± 2 mV).
7. Remove the voltmeter leads from the oxygen amplifier’s test points.
8. Plug the voltmeter leads into the test points on the CO amplifier. Plug the positive lead into the red
(+) test point; plug the negative lead into the black (-) test point.
9. Verify a voltmeter reading of 100 mV (± 2 mV).
10. If necessary, use a small flat-blade screwdriver to adjust the zero potentiometer until the voltmeter
reading is 100 mV (± 2 mV).
11. Remove the voltmeter leads from the CO amplifier’s test points.
12. Close the housing door.
Maintenance
This section describes maintenance procedures. It includes preventive maintenance procedures. This
section also includes procedures to troubleshoot the sample-draw detector, replace components of the
sample-draw detector, adjust the low flow setting, and remove the particle filter’s tubing stub.
Preventive Maintenance
This section describes a preventive maintenance schedule to ensure the optimum performance of the
sample-draw detector. It includes daily and quarterly procedures.
Daily Visual Checks
1. Verify that the Pilot LED is on.
2. Verify that the flowmeter indicates a flow rate of approximately 1.0 SCFH. If necessary use the
sensor flow control valve to adjust the flow rate to 1.0 SCFH. Turn the valve’s knob clockwise to
increase the flow and counterclockwise to decrease the flow.
3. Verify a display reading of 20.9% for the oxygen channel and 0 ppm for the CO channel at the
controller. Investigate significant changes in the display reading.
Quarterly Calibration
Calibrate the sample-draw detector as described in “Calibration, Oxygen Sensor” on page 25 and
“Calibration, CO Sensor” on page 27.
