RKI Instruments 65-2442RK - Manual (Page 19)

65-2442RK PPM Hydrogen Transmitter • 15
Calibration
This section describes how to calibrate the ppm hydrogen transmitter. It includes
procedures to prepare for calibration, set the zero reading, set the response reading, and
return to normal operation.
WARNING: The controller is not an active gas monitoring device during the calibration
procedure.
NOTE: The following procedure assumes the use of a calibration kit which includes a
calibration gas cylinder, a 0.5 LPM fixed flow regulator with an on/off knob, a
calibration cup for the detector, and a humidifier tube to connect the regulator to
the calibration cup.
Calibration Kit Humidifier Tube
The ppm hydrogen detector requires normal atmospheric humidity levels to respond
properly to hydrogen. Normal atmospheric humidity variations do not affect the
detector’s response to hydrogen in ambient air, but the ultra low humidity level of gas
from a calibration cylinder requires that the calibration sample be humidified for the
detector to respond properly. The calibration kit for the ppm hydrogen transmitter
includes a humidifier tube that is not normally included in other calibration kits. This
humidifier tube humidifies the calibration sample flowing through it by absorbing
humidity from the ambient air and adding it to the sample. The humidifier tube is
included in the “Parts List” on page 17.
WARNING: A humidifier tube must be used when calibrating the ppm hydrogen
transmitter test for the detector to respond properly to the calibration gas.
Failure to use a humidifier tube will result in an inaccurate calibration.
Preparing for Calibration
1. Screw the calibration cup onto the bottom of the hydrogen detector.
2. Use the humidifier tube to connect the regulator to the calibration cup.
3. Set a voltmeter to measure in the millivolt (mV) range.
4. Remove the junction box cover, then plug the voltmeter leads into the test points on
the amplifier.
Plug the positive lead into the red + test point; plug the negative lead into the black -
test point.
5. 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 1,000 ppm hydrogen and a fullscale setting
of 2,000 ppm hydrogen, the correct output is 300 mV.
300(mV) = (1000/2000) X 400 +100
6. Place the controller into its calibration mode or disable external alarms.