RKI Instruments 35-3010RKA-04 User Manual
Page 24
20 • 35-3010RKA-04 Sample-Draw Detector
4.
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.
2.
Connect the calibration kit sample 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 gas to flow for one minute.
5.
Verify a voltmeter reading of 100 mV ± 2 mV at the test points as described in the
Preparing for Calibration section above.
6.
If necessary, use a small flat-blade screwdriver to adjust the zero pot until the
voltmeter reading is 100 mV ± 2 mV.
7.
Disconnect the sample tubing from the inlet line.
8.
Unscrew the regulator from the zero air calibration cylinder. Leave the sample tubing
connected to the regulator.
Setting the Response Reading
1.
Screw the regulator into the 3-gas calibration cylinder.
2.
Connect the sample tubing from the regulator to the inlet line at or near the sample-
draw detector’s INLET fitting.
3.
Allow the calibration gas to flow for one minute.
4.
Check the mV output on the LEL transmitter test points and verify that the reading
matches the response reading (±2 mV) you determined earlier.
5.
If necessary, use the span pot on the LEL transmitter to adjust the reading to match the
correct response reading.
6.
Disconnect the sample tubing from the sample-draw detector’s inlet line.
7.
Unscrew the regulator from the calibration cylinder.
NOTE:
For convenience, leave the regulator connected to the sample tubing.
Returning to Normal Operation
1.
Remove the voltmeter leads from the test points.
2.
Reconnect the incoming sample line.
3.
Wait 1 to 2 minutes to allow the calibration gas to be drawn out and the reading to
stabilize.
4.
Close the housing door.