A simple two-point calibration is all that is required to calibrate the CWE GEMINI O2 & CO2 Monitor, the process for which is outlined below.
To calibrate the CO2 sensor, you will need a ZERO gas (room air or N2) and a SPAN gas (5% or 10% CO2). To calibrate the O2 sensor, you will need a ZERO gas (N2) and a SPAN gas (room air or 50% or 100% O2). A convenient calibration gas mix is 5% CO2, balance N2. This serves as both CO2 SPAN and O2 ZERO. This gas mix is commercially available in small canisters.
It is important to note that you should NEVER apply compressed gas directly to the SAMPLE INLET. When calibrating with any compressed gas, allow the GEMINI to draw in the gas from a stream or from a Tedlar Sampling Bag similar to the ones found HERE.
Please reference the image below during the various calibration steps.
- ZERO Calibrations
For either CO2 or O2 ZERO calibration, first sample the calibration gas and allow the reading to stabilize. Then, press the corresponding ZERO push button. The display will prompt you to press the ADJUST KNOB when ready. The display will then appear as follows, and the small LED next to the ZERO push button will blink.
After about twenty seconds the display will return to normal, and the zero gas value will be recorded. This function is the same for CO2 or O2, but be sure to use the appropriate calibration gas.
- SPAN Calibrations
This function is similar to the ZERO calibrations. Sample the calibration gas until a stable reading is shown. Press the relevant SPAN push button and follow the prompts (O2 SPAN shown below). Turn the ADJUST KNOB until the correct reading is shown on the display. Press the ADJUST KNOB and the display will return to normal.
For further technical assistance with this or any other issue, please contact ADInstruments Technical Support by clicking HERE.