But how does the Arduinos fare against humidity, high/low temperatures, vapours, vibration, electromagnetic noise, etc? Has anyone got it working in such environments?
My next project will put an Arduino Duemilanove working near powerful pumps, valves, and corrosive chemical tanks (like acids and lye/caustic soda). Let's see how it performs!
The arduino uses pretty much "standard" construction, almost certainly suitable for "commercial" environments, but it is in no way specifically "hardened" against especially harsh "industrial" environments. At 30 units per year, I'd be inclined to throw your electronics inside a sealed box of some kind, and spend your extra time working on buttons/etc that don't involve putting holes in the box (magnetic reed switches, photosensors, etc.)