12 • 35-3001A-14 Methane Sample-Draw Detector
Setting the Zero Reading
CAUTION:
If you suspect the presence of combustible or toxic gas or an abnormal oxygen
concentration in the monitoring environment, use the calibration kit and the zero air
calibration cylinder to introduce “fresh air” to the sensor and verify an accurate
zero setting. See “Calibration” on page 18 for instructions on using a zero air
calibration cylinder for setting the zero reading.
1. Verify that the sample-draw detector is sampling a fresh air environment (environment known to be
free of combustible and toxic gas and of normal oxygen concentration, 20.9%).
2. Verify a reading of 0% LEL on the controller display screen for the applicable channel.
If the display reading is 0% LEL both channels, start up is complete. The sample-draw detector is in
normal operation. If the display reading is not 0% LEL for both channels, continue with step 3.
3. Perform a zero (fresh air) operation at the controller. See “Calibration” on page 18 for instructions to
perform a zero (fresh air) operation.
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 biannual 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 0% LEL for both channels. Investigate significant changes in the display
reading.
Biannual Calibration
Calibrate the sample-draw detector as described in “Calibration” on page 18.
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.
