A: The Zirc oxide sensor takes a few minutes to warm up. When you say "leaving the analyzer on without gas flowing," I'm assuming you mean air will eventually get to it. If the unit is powered down, air exposure is no problem. Even if it is exposed to air, it's not as detrimental to a ZrO2 sensor as it is with a fuel-cell, but exposing it to high O2 while powered will result in a slower recovery time. We're talking minutes, not hours.
The one drawback of the ZrO2 is that it can only read trace. Depending on the configuration, the sensor will saturate before getting anywhere near percent levels. You may want to run the application and customer's desired O2 range by us just to make sure.
