User Manual

35-3010RKA-06 Sample-Draw Detector • 19

Calibration

This secti on de scrib es ho w to cal ibra te the sample-dra w adapter. It includes procedur es to

prepare for calibration, set the zero reading for each channel, set the response reading for

each channel, and return to normal operation.

NOTE: This procedure describes calibration using a demand flow regulator, a zero air

calibration cylinder, a nd a 4-gas calibration cylind er.

Preparing for Calibration

CAUTION: This proce dure 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.

3. When checking the mV output of each channel, plug the voltmeter lead s into the

app rop riate tes t poin t s .

For the LEL chan nel, plug the voltmeter leads 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-.

For the H

S channel, plug the voltmeter 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 in to the test point labeled CAL-2.

4. Use the following formula to determine the correct test points output for the

calibrating sample.

Output (mV) = (calibratin g 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.

2. Connect the calibration kit sa mple tubing to the regulator.

3. Connect the sample tubing from the regulator to the inlet line at or near the INLET

fitting.

4. Allow the g as to fl ow for one minute.

5. Verify a voltmeter reading of 100 mV ± 2 mV at the test points for each channel as

described in the Preparing for Calibration section above.

6. If necessary, use a s mall flat-bla de screwdriver to adjust the zero pot for the

appropriate channel until the voltmeter reading is 100 mV ± 2 mV.