35-3001A-04-02 Carbon Monoxide Sample-Draw Detector • 17
6. If necessary, use a small flat-blade screwdriver to adjust the zero potentiometer until the
voltmeter reading is 100 mV (± 2 mV).
7. Remove the voltmeter leads from the test points.
8. 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
counterclockwise to increase the flow and clockwise to decrease the flow.
3. Verify a display reading of 0 ppm at the controller. Investigate significant changes in the
display reading.
Quarterly Calibration
Calibrate the sample-draw detector as described in “Calibration” on page 24.
Troubleshooting
The troubleshooting guide describes symptoms, probable causes, and recommended action for
problems you may encounter with the sample-draw detector.
NOTE:
This troubleshooting guide describes sample-draw detector problems only. See the
controller Operator’s Manual if the controller exhibits any problems.
Fail Condition
Symptoms
•
The sample-draw detector’s Fail LED is on.
•
The monitoring device is operating properly but indicates a reading well below zero.
Probable causes
•
The sample-draw detector’s flow rate is too low because of an obstructed sample line, failed
pump, etc.
•
The sample-draw detector is malfunctioning.
•
The sensor wiring is disconnected or misconnected.
Recommended action
1. At the sample-draw detector, set the correct flow rate with the sensor flow control valve.
2. If you cannot set the correct flow rate, check the sample lines for obstructions or kinks.
