Manually Calibrating the phx21 After a 30-Minute Warm-Up

1. Tap Menu.

2. Tap Calibrate.

3. Tap Calibrate at the bottom-left.

4. Type the actual PPM for the cylinder into the PPM field. Zero will be the first gas and is already populated.

5. Apply gas for 10 seconds and then tap Generate.

6. Let the timer count down.

The phx21 will sample the gas, then the PPM value will be added to the list of Current Calibrations on phx21. Repeat Steps 4-6 until all the Calibration Spans have been added, then tap Done.