ZERO screen displays.

To skip the ZERO procedure and move directly to the span calibration procedure, push the p button. If no button is pushed for 30 seconds, the device prompts user to perform a SPAN calibration before device returns to the Normal Measurement page.

To perform ONLY a Fresh Air Setup at this time, press the button. The device then performs a Fresh Air Setup as described in Turning ON and Fresh Air Setup . When the Fresh Air Setup is complete, the device returns to the normal Measure screen.

The message "SENSOR REFRESH" displays, followed by the message "ZERO CALIBRATION".

The "REFRESH" message does not appear if a catalytic combustible sensor is not installed.

ZERO calibration starts.

A progress bar shows the user how much of the calibration has been completed.

During the first moments of a ZERO calibration, the combustible sensor reading may be replaced by a moving display of “PLEASE WAIT”. This is normal.

After the ZERO calibration is completed the device displays either

“ZERO CALIBRATION PASS”

or

“ZERO CALIBRATION FAIL”.