16 • 65-2443 PPM Hydrogen Transmitter
11. Allow the transmitter to run for 3 hours.
12. Perform a preliminary calibration as described on page 16. This will be a temporary calibration
since the new ppm detector must burn-in before it can be properly calibrated.
13. Allow the replacement detector to burn-in for at least 5 days
before you continue with the next
step. A burn-in period of 7 days is recommended.
14. After the burn-in period, calibrate the transmitter as described on page 16.
Calibration Frequency
Although there is no particular calibration frequency that is correct for all ppm hydrogen transmitter
applications, a calibration frequency of every 6 to 12 months is adequate for most applications. Unless
experience in a particular application dictates otherwise, RKI Instruments, Inc. recommends a
calibration frequency of every 6 months.
If an application is not very demanding, for example detection in a clean, temperature controlled
environment where hydrogen is not normally present, and calibration adjustments are minimal at
calibration, then a calibration frequency of every 12 months is adequate.
If an application is very demanding, for example if hydrogen is present often and in significant
concentrations or the environment is not well controlled, then more frequent calibration than every 6
months may be necessary.
Calibration
This section describes how to calibrate the ppm hydrogen transmitter. It includes procedures to prepare
for calibration, set the span reading, set the linearization, 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 2 calibration gas
cylinders, 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 18.
