35-3001A-13-XX CO
2
/CO Sample-Draw Detector • 27
6. Use the following formula to determine the correct test points output for the test sample.
Output (mV) = (calibrating sample/fullscale) X 400 + 100
For example, with a test sample of 50 ppm and a fullscale setting of 300 ppm, the correct output is 200 mV.
167 (mV) = (50/300) X 400 +100
Setting the Zero Reading
1. Connect the sample tubing from the demand flow regulator to the sample-draw detector’s inlet fitting.
This
step is not necessary if you verified a fresh air environment earlier in this procedure.
2. Allow the sample draw detector to draw sample for one minute.
3. Verify a voltmeter reading of 100 mV (± 2 mV).
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 fitting.
6. Unscrew the regulator from the zero air calibration cylinder.
Setting the Response Reading
1. Screw the demand flow regulator onto the carbon monoxide 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. 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 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 approximately one minute to allow the carbon monoxide 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.
