RKI Instruments 35-3010RKA-07 - Manual (Page 23)

35-3010RKA-07 Sample-Draw Detector • 19
and H
2
S sensors and every 6 months for the IR CH
4
sensor in the sample draw detector.
If an application is not very demanding, for example detection in a clean, temperature
controlled environment, and calibration adjustments are minimal at calibration, then a
calibration frequency of every 6 months for the oxygen and H
2
S sensors and every 12
months for the IR CH
4
sensor is adequate for the sample draw detector.
If the application is very demanding, for example if the environment is not well
controlled, then more frequent calibration than every 3 months for the oxygen and H
2
S
sensors and every 6 months for the IR CH
4
sensor may be necessary for the sample draw
detector.
Calibration, IR CH
4
and H
2
S Detectors
This section describes how to calibrate the IR CH
4
and H
2
S sensors in the sample draw
detector. It includes procedures to prepare for calibration, set the zero reading, set the
response reading, and return to normal operation.
NOTE: This procedure describes calibration using a demand flow regulator, a zero air
calibration cylinder, and a 4-gas calibration cylinder.
Preparing for Calibration
CAUTION: This procedure may cause alarms at the controller. Take appropriate action to avoid
this, such as entering the calibration mode at the controller.
1. Open the housing door.
2. Set a voltmeter to measure in the millivolt (mV) range.
• When checking the mV output of the IR CH
4
channel, plug the voltmeter into the
test points on the LEL transmitter. Plug the positive lead into the test point labeled
TP+
; plug the negative lead into the test point labeled TP-.
• When checking the mV output of the H
2
S channel, plug the voltmeter leads into
the test points in the AMP 2 section of the main circuit board. Plug the positive
lead into the test point labeled CAL+2; plug the negative lead into the test point
labeled CAL-2.
3. 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 methane and a fullscale setting of
100%LEL, the correct output for the LEL test points is 300 mV.
300 (mV) = (50/100) X 400 +100
Setting the Zero Reading
NOTE: If you can verify a fresh air environment, it is not necessary to use the zero air
calibration cylinder to set the zero reading.
1. Screw the regulator into the zero air calibration cylinder.