35-3001A-14 Methane Sample-Draw Detector • 19
4. If necessary, use a small flat-blade screwdriver to adjust the zero potentiometer until the voltmeter
reading is 100 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
Response Reading.
5. Disconnect the sample tubing from the inlet line.
6. Unscrew the regulator from the zero air calibration cylinder.
Setting the Response Reading
1. Screw the regulator into the methane calibration cylinder.
2. Connect the sample tubing from the demand flow regulator to the sample-draw detector’s inlet line.
3. Allow the sample-draw detector to draw sample for one minute.
4. When the reading on the voltmeter stabilizes, verify that the reading matches the response reading
(±2 mV) you determined earlier.
5. If necessary, use the span potentiometer on the amplifier to adjust the reading to match the correct
response reading.
6. Disconnect the sample tubing from the inlet line.
7. Unscrew the regulator from the methane calibration cylinder.
Returning to Normal Operation
1. Wait approximately one minute to allow the methane reading to stabilize.
2. Remove the voltmeter leads from the amplifier test points.
3. Close the housing door.
4. Follow the instructions in the controller’s operator’s manual to exit the calibration mode.
5. Store the components of the calibration kit in a safe and convenient place.
