65-2405RK-05-04 Combustible Gas Transmitter • 19
Calibration
This section describes how to calibrate the combustible gas transmitter. It includes procedures to
prepare for calibration, set the zero reading, set the response reading, and return to normal operation.
WARNING: The controller is not an active gas monitoring device during the calibration
procedure.
NOTE:
The following procedure assumes the use of a calibration kit which includes a calibration gas
cylinder, a 0.5 LPM fixed flow regulator with an on/off knob, a calibration cup for the
detector, and a short piece of sample tubing to connect the regulator to the calibration cup.
Preparing for Calibration
NOTE:
Calibrating the combustible gas transmitter may cause alarms. Be sure to put the controller
into its calibration program or disable external alarms before continuing.
WARNING: Do not remove the junction box cover while the circuits are energized unless the area
is determined to be non-hazardous. Keep the junction box cover tightly closed during
operation.
1. Unscrew and remove the junction box cover.
2. Set a voltmeter to measure in the millivolt (mV) range.
3. Plug the voltmeter leads into the test points on the amplifier. Plug the positive lead into the red (+)
test point; plug the negative lead into the black (-) test point.
4. Use the following formula to determine the correct test points output for the calibrating sample.
Output (mV) = (calibrating sample/fullscale) X 400 + 100
For example, with a calibrating sample of 50% LEL and a fullscale setting of 100% LEL, the
correct output is 300 mV.
300(mV) = (50/100) X 400 +100
5. Screw the calibration cup on the detector housing.
Setting the Zero Reading
NOTE:
If you can verify that the combustible gas transmitter is in a fresh air environment, you do not
need to apply zero air to the detector before adjusting the zero reading.
1. Screw the regulator into the zero air calibration cylinder.
2. Use the calibration kit sample tubing to connect the regulator to the calibration cup.
3. Turn the regulator’s on/off knob counterclockwise to open the regulator.
