RKI Instruments 65-2400RK-05 - Manual (Page 13)

Combustible Gas Transmitter • 13
Calibration
This section describes how to calibrate the combustible gas transmitter. It includes
procedures to prepare for calibration, enter the Calibrate program, set the zero reading, set
the response reading, and return to normal operation.
NOTE: Calibrating the transmitter may cause alarms. Be sure to put the controller into
calibration mode or disable external alarms before calibration.
Preparing for Calibration
1. Slide the calibration cup over the bottom of the combustible gas detector, then secure
the calibration cup to the detector with the thumb screw.
2. Use the sample tubing to connect the regulator to the calibration cup.
NOTE: Do not screw the regulator into the zero air calibration cylinder at this time. If
you can verify a fresh air environment, you will not need to apply gas from the
zero air cylinder when setting the zero.
3. Set a voltmeter to measure in the millivolt (mV) range.
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 operaiton.
4. Remove the junction box cover, then plug the voltmeter leads into the test points on
the amplifier.
Plug the positive lead into the test point labeled TP+ ; plug the negative lead into the
test point labeled TP- .
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
Setting the Zero Reading
1. Screw the regulator into the zero air calibration cylinder.
2. When the reading on the voltmeter stabilizes, 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).
3. 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.
2. When the reading on the voltmeter stabilizes, verify that the reading matches the