RKI Instruments 65-2391RK - Manual (Page 12)

8 • 65-2391RK CO
2
Transmitter
Maintenance
This section describes maintenance procedures. It includes preventive maintenance,
troubleshooting, and component replacement procedures.
Preventive Maintenance
This section describes a preventive maintenance schedule to ensure the optimum
performance of the CO
2
transmitter. It includes daily, monthly, and biannual procedures.
Daily
Verify a display reading at the controller of the background concentration of CO
2
. Typical
background concentrations of CO
2
vary from about 300 to 600 ppm (0.03 to 0.06 %volume)
depending on location. The 0-5,000 ppm and 0-5 %volume detectors will display a reading
in a fresh air environment because they have low ranges. The 0-50 %volume and 0-100%
volume detectors will not display a reading in fresh air because their ranges are too large.
Investigate significant changes in the display reading.
Monthly
This procedure describes a test to verify that the CO
2
transmitter responds properly to the
target gas.
WARNING: The controller is not an active gas monitoring device during the response
test procedure.
NOTE: Performing a response test on the CO
2
transmitter may cause alarms. Be sure to
put the controller into its calibration program or disable external alarms before
performing this test.
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 the response test
1. Place the controller into its calibration program or disable external alarms.
2. Verify that the controller display reading for the channel you are testing is consistent
with typical background levels of CO
2
.
If the display reading is not consistent with typical background levels of CO
2
, set the
zero reading of the transmitter as described in “Start Up” on page 6 of this manual,
then continue this procedure.
3. Screw the calibration cup onto the bottom of the detector.
4. Use the calibration kit sample tubing to connect the regulator to the calibration cup.
5. Set a voltmeter to measure in the millivolt (mV) range.
6. 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