RKI Instruments 65-2396RK User Manual
Page 19
65-2396RK CO
2
Transmitter • 15
Setting the Zero Reading
Since there is a background of CO
2
in air of typically 300 - 600 ppm (0.03 - 0.06 %volume),
it is necessary to use a calibration kit with a 100% nitrogen cylinder to set the zero signal of
a CO
2
transmitter with a low range detector. Fresh air can be used to zero the transmitter
if a 0-50 %volume or 0-100 %volume detector is being used.
1.
Screw the regulator into the 100% nitrogen calibration cylinder.
2.
Use the calibration kit sample tubing to connect the regulator to the calibration cup.
3.
Turn the regulator’s on/off knob counterclockwise to open the regulator.
4.
Allow the gas to flow for one minute and verify a reading of 100 mV (±2 mV). If
necessary, use the zero pot on the amplifier to adjust the reading to 100 mV (±2 mV).
5.
Turn the regulator’s on/off knob clockwise to close the regulator.
6.
Unscrew the regulator from the 100% nitrogen calibration cylinder.
7.
Leave the sample tubing connected to the regulator and the calibration cup.
Setting the Response Reading
1.
Screw the regulator into the calibration cylinder. Verify that the calibration gas is
representative of the transmitter’s target gas.
2.
Turn the regulator’s on/off knob counterclockwise to open the regulator.
3.
Allow the calibration gas to flow for one minute and verify that the reading matches
the response reading (±2 mV) you determined earlier. If necessary, use the span pot on
the amplifier to adjust the reading to match the correct response reading.
4.
Turn the regulator’s on/off knob clockwise to close the regulator.
5.
Unscrew the regulator from the calibration cylinder.
Returning to Normal Operation
1.
Remove the voltmeter leads from the amplifier test points.
2.
Unscrew the calibration cup from the detector.
NOTE:
For convenience, leave the regulator and calibration cup connected by the
sample tubing.
3.
Secure the junction box cover to the junction box.
4.
When the controller display reading falls below the alarm setpoints, return the
controller to normal operation.
5.
Verify that the controller display reading decreases and stabilizes at a typical
background CO
2
level. The 0-5,000 ppm and 0-5 %volume detectors will display a
reading in a fresh air environment because they have low ranges. The 0-50 %volume
and 0-100 %volume detectors will not display a reading in fresh air because their
ranges are too large.
6.
Store the components of the calibration kit in a safe and convenient place.