After seeing Smoke2Vape's video....
YouTube - ‪S2V4 REVIEW Does an E-cig set a fire alarm off?‬‏
I decided to [stupidly] impress a work colleague by showing him how an e-cig won't set of the smoke detectors, even if you blow vapour right into them....I was wrong! A few seconds after I did it the alarm went off and the whole company had to evacuate the building (about 100 people or so).
I was desperately hoping that is was just a bizarre coincidence but when we were allowed back in the maintenence man was in my office looking at our alarm and asked me "It was set off here, you don't why do you?", I played dumb and sat back down whilst he reset it and I slowley moved my e-cigs off the table and into my pocket before he could put 2 and 2 together.
My office is small and can only accomodate three people. The other two people are [now] former smokers and use e-cigs too and none of us want to lose our ability to vape in the office so they stayed quiet (after they stopped laughing at me of course) but I certainly won't be trying that again!!
The odd thing is, all three of us have been vaping in there at the same time before and made it very cloudy which has never set the alrm off before. It only went off when I made a specific efort to blow my vapour directly into the sensor (like Andy does in the video).
This is a worry though because although I was stupid to do what I did, if large volumes of vapour can set off fire alarms it's a very easy reason to ban them from indoor use. Luckily, despite most people (including the maintenence man) knowing I vape no one important has realised it was the ecig that caused the alarm and evacuation.
The detector in question was one of thesehttp://www.cooper-ls.com/downloads/mf20-22.pdf
Which seem to use a light sensor that goes off if interupted, so anything 'smoke-like' would set it off, including vapour of just a big cloud of dust. Worrying!!!