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Calibration, ir ch, And h, S detectors – RKI Instruments 35-3010RKA-07 User Manual

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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.