RKI Instruments 65-2391RK - Manual (Page 17)

65-2391RK CO
2
Transmitter • 13
NOTE: When first powered up, the transmitter will enter about a one minute period
when the 4-20 mA output is stabilizing and may be above the controller alarm
points or well below zero momentarily. RKI controllers have a one minute
warmup period when the controller does not display any gas reading or give any
alarm indication. The CO
2
transmitter’s 4-20 mA signal should be stable by the
time the controller’s warmup period is over.
CAUTION: Allow the detector to warm up for 5 minutes before you continue with the next step.
14. Calibrate the CO
2
transmitter as described in “Calibration” on page 13 of this manual.
Calibration Frequency
Although there is no particular calibration frequency that is correct for all applications, a
calibration frequency of every 6 months is adequate for most infrared CO
2
transmitter
applications. Unless experience in a particular application dictates otherwise, RKI
Instruments, Inc. recommends a calibration frequency of every 6 months for the infrared
CO
2
transmitter.
If an application is not very demanding, for example detection in a clean, temperature
controlled environment where calibration adjustments are minimal at calibration, then a
calibration frequency of every 9 to 12 months is adequate.
If an application is very demanding, for example if the environment is not well controlled,
then more frequent calibration than every 6 months may be necessary.
Calibration
This section describes how to calibrate the CO
2
transmitter. It includes procedures to
prepare for calibration, set the zero reading, set the response reading, and return to
normal operation.
WARNING: The controller is not an active gas monitoring device during the calibration
procedure.
NOTE: The following procedure assumes the use of a calibration kit which includes a
CO
2
calibration gas cylinder, a 100% nitrogen 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 Calibration
1. Screw the calibration cup onto the bottom of the CO
2
detector.
2. Use the sample tubing that comes with the calibration kit to connect the regulator to
the calibration cup.
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