RKI Instruments 65-2390RK - Manual (Page 18)

14 • 65-2390RK Combustible Gas Transmitter
5. 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
6. Place the controller into its calibration program or disable external alarms.
NOTE: Calibrating the combustible transmitter may cause alarms. Be sure to put the
controller into its calibration program or disable external alarms before
continuing.
Setting the Zero Reading
CAUTION: If you can verify that the combustible 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. Turn the regulator knob counterclockwise to open the regulator.
3. Allow the gas to flow for one minute and verify a reading of 100 mV (±2 mV). If
necessary, use the zero potentiometer on the amplifier to adjust the reading to 100 mV
(±2 mV).
4. Turn the regulator knob clockwise to close the regulator.
5. Unscrew the regulator from the zero air calibration cylinder. Leave the sample tubing
connected to the regulator and the calibration cup.
Setting the Response Reading
1. Screw the regulator into the calibration cylinder. Verify that the calibration gas is
representative of the transmitter’s target gas.
2. Turn the regulator knob counterclockwise to open the regulator.
3. Allow the calibration gas to flow for one minute and verify that the reading matches
the response reading (±2 mV) you determined earlier. If necessary, use the span
potentiometer on the amplifier to adjust the reading to match the correct response
reading.
4. Turn the regulator knob clockwise to close the regulator.
5. Unscrew the regulator from the calibration cylinder.
Returning to Normal Operation
1. Remove the voltmeter leads from the amplifier test points.
2. Unscrew the calibration cup from the detector.
NOTE: For convenience, leave the regulator and calibration cup connected by the
sample tubing.
3. Secure the junction box cover to the junction box.
4. When the display reading falls below the alarm setpoints, return the controller to