65-2427-05-01 H
2
S Detector • 17
4. Put the controller into its calibration program.
Setting the Zero Reading
NOTE:
If you can verify that the H
2
S detector is in a fresh air environment, you do not need
to apply zero air to the detector before adjusting the zero reading.
1. Follow the directions in the controller operator’s manual for setting the zero reading.
2. When the instructions call for applying zero air to the detector, turn the regulator’s on/off
knob counterclockwise to open it.
3. Allow the gas to flow for two minutes.
4. Set the zero reading according to the controller operator’s manual.
5. Turn the regulator’s on/off knob clockwise to close it.
6. Unscrew the regulator from the zero air calibration cylinder.
7. Leave the sample tubing connected to the regulator and the calibration cup.
NOTE:
Depending on the size of your zero air cylinder, it is possible that you will have a
different regulator for the zero air cylinder and the H
2
S gas cylinder. If necessary to
fit the H
2
S calibration gas cylinder, change the regulator.
Setting the Span Reading
8. Follow the directions in the controller operator’s manual for setting the response reading
(span).
9. For toxic gas cylinders (like H
2
S), it is important to vent the regulator while installing it
onto the cylinder. Venting the regulator during installation helps prevent air from getting
into the cylinder and degrading the gas. When the directions call for exposing the detector
to gas, open the regulator by turning the knob counterclockwise and then install it onto the
cylinder.
10. Allow gas to flow for 2 minutes.
11. Set the response reading according to the controller operator’s manual.
12. After setting the response reading, turn the regulator’s on/off knob clockwise to close it.
13. Unscrew the regulator from the cylinder.
14. Remove the calibration cup from the detector.
NOTE:
For convenience, leave regulator and calibration cup connected by the sample tubing.
Returning to Normal Operation
1. Allow about 45 seconds for the gas reading to decrease below the alarm points and then
return the controller to normal operation.
