RKI Instruments 65-2432RK - Manual (Page 16)

65-2432RK CO Transmitter • 16
CAUTION: Allow the replacement detector to warm up for 5 minutes before you continue with
the next step.
11. Calibrate the replacement detector as described in the Calibration section of this
manual.
12. Secure the junction box cover to the junction box.
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 calibration using a fixed flow regulator which has no on/
off knob and allows sample to flow as soon as it is screwed into a cylinder. RKI
Instruments, Inc. recommends using a 0.5 LPM (liters per minute) fixed flow regulator.
Preparing for Calibration
1. Screw the calibration cup onto the bottom of the CO detector.
2. Use the sample tubing to connect the fixed flow regulator to the calibration cup.
NOTE: Do not screw the regulator into the zero air calibration cylinder at this time.
3. Set a voltmeter to measure in the millivolt (mV) range.
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 PPM CO and a fullscale setting of
300 PPM, the correct output is 167 mV.
167 (mV) = (50/300) X 400 +100
NOTE: Calibrating the CO transmitter may cause alarms. Be sure to put the controller
into its calibration program or disable external alarms before continuing.
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. Screw the regulator into the zero air calibration cylinder. Gas will automatically
begin to flow.
2. Allow the gas to flow for two minutes, then verify a reading of 100 mV (± 2mV). If
necessary, use the zero potentiometer on the amplifier to adjust the reading to 100