Smoke detectors and fog

jds10011

Member
Disclaimer -- this is a post looking for information to share with the "important" people with decision-making capabilities. Nobody else will be taking any action, other than sending emails to "important" people.

Many years ago we disallowed fog machines in our space as they tend to set off the smoke detectors (and therefore fire alarm) and of course this makes many people grumpy. The space has rather simple smoke detectors that look like they belong in a bedroom -- nothing too fancy in appearance. A recent group told us that they became aware of a new variety of smoke detector not available decades ago, which claims to use a microprocessor and multiple sensors to avoid nuisance alarms -- apparently called a "multi-criteria smoke detector" -- one manufacturer describes this as using "artificial intelligence techniques that can differentiate and classify smoke & fire profiles." Obviously, we will leave it to the appropriate authorities to determine code compliance, contracting with the appropriate parties to install/inspect, etc., but the question here is: Do these sorts of detectors really allow us to use fog (even copious amounts) without setting off the alarm? If so, do folks have experience with particular manufacturers/models? Any other info that would help us know whether this is worth pursuing, or info to pass along to the "important" people?

Thanks!
 
Not sure if that is a thing but could be wrong. In one of my venues we have what is called a multi mode detector. When fully active it can detect smoke and thermal but when we have an isolation done the only the smoke part is isolated and the thermal part is still active. This gives some fire alarm protection but if the thermal is to trip the fire alarm there must be quite a bit of heat so the "fire" would be quite big at that stage.
I will be interested to know if the new detectors you mentioned exist and to what application they can be applied.
 
We had mostly heat type detectors except one location off stage with a smoke. We had a system approved by our public safety dept. where for events using haze/smoke we covered the detector, calling PS to inform them. We literally gaff taped a cardboard coffee cup to it. NYFD was onboard with all this and we had the required haze/smoke FDNY yearly permit.
 
Realistically, you need to discuss this with a fire protection contractor (likely the one who annually inspects your system and is familiar with the space). Yes, you have local detectors distributed around, but you may also have particle detectors in your HVAC system and elsewhere -- and your current head-end of the FA system could be tied in with other areas of the building so upgrading one area may have much broader implications.

A common solution is putting an alarm system into bypass on nights with fog/haze and have a designated fire watch to monitor for pre-alarms and go investigate. This is a plan you would develop in conjunction with your AHJ (authority having jurisdiction aka fire marshal).

Redoing your detection and alarm system is likely tens of thousands of dollars, though more likely six figures. There certainly are better options for detection but they come at a cost premium, especially with an older existing install. This isn't just replacing detectors. It's a a comprehensive analysis of your overall system and likely adding or relocating devices to an extent that may trigger you to modernize to current codes and open a Pandora's Box of implications. Generally speaking, as you get into more intricate detectors, you're also looking at considerations for smoke stratification and so forth that can result in adding a large number of additional devices beyond what you currently have.
 
We had mostly heat type detectors except one location off stage with a smoke. We had a system approved by our public safety dept. where for events using haze/smoke we covered the detector, calling PS to inform them. We literally gaff taped a cardboard coffee cup to it. NYFD was onboard with all this and we had the required haze/smoke FDNY yearly permit.
yikes ...
 

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