[SML] Smoke vs Heat vs Rate of Rise detectors

[Dougherty, Jim]

I'll second the recommendation to include your AHJ, your alarm system contractor, and your Powers That Be early in the process.  Demonstrate the atmospheric effects that you use in your space - fog and haze will false trip many systems.  We underwent an upgrade some years ago and the decision was made to try a camera-based system; it was meant to be able to detect fire and flame by analyzing the video image (not a fire system engineer, don't know the details) specifically to avoid false activations through what we do.  It was pricey, we were early adopters, and it was a big investment.  Long story short, it didn't work.  It thought moving draperies/fog/a patron fanning themselves with a program were all flame and we experienced many false alarms, mid-show.  However, because communication was good throughout we ended up with a solution that works.  They were able to pull that system out and replace with other compliant equipment - primarily heat and rate-of-rise based.  The only trips we've had since were faulty sensors that were replaced and the troubles ceased.

Regarding the mist systems mentioned, I like the idea but why distilled water? Is there a large reservoir somewhere in the building to draw from? I'd think any benefit of it being distilled might go away over time in storage.

- Jim Dougherty
Middlebury College Theatre Dept.