[SML] Smoke vs Heat vs Rate of Rise detectors

[Dale Farmer]

On 3/8/2022 9:29 PM, Dale Farmer via Stagecraft wrote:
> On 3/8/2022 9:35 AM, Dougherty, Jim via Stagecraft wrote:
>> 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!
>   o!
>>   nly 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.
>>
>> _____
>    the reason for the distilled water, and yeah there is a storage tank 
> that has to be periodically drained and refilled, is to make the system 
> safe for use on energized electrical equipment.  Once the tank is 
> drained, it switches over to regular water supply.   Regular water mist 
> will have enough trace chemicals in it to cause short circuits in 
> energized electrical gear. Especially if your area has hard water.
> 
>    The systems are sized such that it will extinguish expected fires, or 
> contain them long enough for fire response to show up.  The huge benefit 
> is that unlike halon systems, it is perfectly harmless to the meat 
> machines that are also in the space, so you don't need to wait for the 
> people to evacuate and the fire to get worse before release.
> 
> There is a video from a cruise line that was retrofitting these into all 
> their ships.  They had engine room fires on a ship with a conventional 
> halon system and one with the water mist system installed. Both very 
> similar causes, a leaking diesel fuel spraying inside the engine.   The 
> halon sysstem worked, and the fire was put put.  The ship needed 
> emergency dry docking and was out of service for three months while the 
> contents of that engine room got replaced.   Several millions in direct 
> damage repairs, tens of millions of refunds of cruise tickets for that 
> three month period.   The ship with the water mist system.  Fire was out 
> before the firefighting team made entry.   Damage was confined to one 
> cylinder of one of the two engines in that engine room, cleanup and 
> repairs were completed at the next port call, mostly because they had to 
> order the parts.  No lost time, repairs cost a few thousand bucks, 
> cleanup was done with mops, buckets and rags by ships crew.
> 
> Here is the video.  They had a camera in the engine room that showed the 
> fire breaking out and being extinguished by the HI_FOG system.
>   https://www.youtube.com/watch?v=tKXiNdJMhgA
> 
> Also here is an article about a system installed in a historic property 
> in the US.
> https://www.securitysystemsnews.com/article/thomas-jefferson-s-home-gets-marioff-water-mist-system 
> 
> 
> Dale
> _____
Memory fail.   only two weeks out of service and only eight million 
dollars in damages.
Dale

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