RKI Instruments 65-2432RK-05 - Manual (Page 18)

14 • 65-2432RK-05 CO Transmitter
Calibration
This section describes how to calibrate the CO transmitter. It includes procedures to
prepare for calibration, set the zero reading, set the response reading, and return to
normal operation. It describes the test using a calibration kit that includes a calibration
cup, calibration gas, sample tubing, and a fixed flow regulator with an on/off knob. RKI
Instruments, Inc. recommends using a 0.5 LPM (liters per minute) fixed flow regulator.
Preparing for Calibration
NOTE: Calibrating the CO transmitter may cause alarms. Be sure to put the controller
into its calibration program or disable external alarms before calibrating.
1. Screw the calibration cup onto the bottom of the CO detector.
2. Screw the regulator into the zero air calibration cylinder.
3. Use the sample tubing to connect the fixed flow regulator to the calibration cup.
4. Set a voltmeter to measure in the millivolt (mV) range.
WARNING: Do not remove the sensor cap or junction box cover while the circuits are
energized unless the area is determined to be non-hazardous. Keep the
sensor cap and junction box cover tightly closed during operation.
5. 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-.
6. 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 PPM CO and a fullscale setting of
300 PPM, the correct output is 167 mV.
167 (mV) = (50/300) X 400 +100
Setting the Zero Reading
NOTE If you can verify that the CO transmitter is in a fresh air environment, you do not
need to apply zero air to the detector before adjusting the zero reading.
1. Turn the regulator on/off knob counterclockwise to open it.
2. Allow the gas to flow for two minutes.
3. Verify a reading of 100 mV (± 2mV).
4. If necessary, use the zero pot on the amplifier to adjust the reading to 100 mV (± 2mV).
5. Turn the regulator on/off knob clockwise to close it.
6. Unscrew the regulator from the zero air calibration cylinder.
Leave the sample tubing connected to the regulator and the calibration cup.