Smoke Vents - article

[BillConnerFASTC]

Until I read this I never realized what that was for on the ceiling of our theater. So we have one but I am fairly sure nobody knows anything about the operation of it.

From my research, much more protection than a fire safety curtain.

 

[SteveB]

From my research, much more protection than a fire safety curtain.

I would think that both are needed, the ceiling vent system, either powered or roof doors, to get the smoke out and the fire curtain to keep the burning stuff out of the audience chamber.

 

[MPowers]

I would think that both are needed, the ceiling vent system, either powered or roof doors, to get the smoke out and the fire curtain to keep the burning stuff out of the audience chamber.

The main point of a fire curtain is to keep smoke, fumes and other gaseous (spelling??) by products of combustion out of the audience chamber until it can be evacuated. The fact that it can also stop immediate, short term propagation of the flames is just a bonus.

 

[brownnathanial]

I would say that it is definitely something important and I think I will be checking with my instructor about the operation of ours.

 

[BillConnerFASTC]

If you have a fire in a fireplace do you expect "smoke, fumes and other gaseous (spelling??) by products of combustion" to enter the room? Same thing. Also, look at theatre fires with deaths - all smoke in top of balcony because the stage was not vented, not because fire. People in the orchestra (and orchestra pit) are usually fine. And to think a piece of cloth is going to resist the pressure of structure fire which can buckle steel doors is kind of short sighted. If the stage does not vent, the curtain will be useless and short lived, even on teh oft chance it does close.

To our non-US members, realize that in the US most fire safety curtains are just cloth (a coated fibreglass) without framing.

Read the Freeman book I noted in article and see if you don't agree.

 

[MNicolai]

To think a piece of cloth is going to resist the pressure of structure fire which can buckle steel doors is kind of short sighted.

My understanding has always been that fire curtains are sacrificial elements intended to provide the audience an additional 10-15 minutes to clear the room before the smoke becomes unbearable, and if you're lucky, enough time for first responders to double check the theater has been cleared. That said, I'd like to think that a deluge curtain lasts at least long enough for on-stage sprinkler heads to activate.

On-stage, I suspect smoke vents help substantially with venting and thus allowing first responders to clear the stage area without quite so much black smoke and heat abating them. However, much depends on how gutsy your fire department is. We invited our entire fire department for a walkthrough two years ago and the summary of the discussions that followed was if you have fire at the counterweight ropes or into the rigging, the stage is an incredibly dangerous place for any first responders to enter. Smoke vents and fire curtains be darned, any fire large enough to require smoke vents is large enough to turn the stage into a place that first responders will almost certainly be unable to enter to fight the fire ---- in that regard, I'd be interested to hear from any experts on opinions about fire curtains potentially impeding firefighting on stage. I'd wonder if a fire on stage is easier to fight from the audience with hoses than from the wings as the rigging disintegrates overhead, and if a fire curtain being in place makes that substantially more difficult short of cutting holes into the curtain to allow for hoses to shoot through it.

Or --- if all of this is a moot point and firefighters would leave it to sprinkler systems (if equipped) to handle the fire, while maybe trying to shoot water into the stagehouse via the open smoke hatches.

 

[BillConnerFASTC]

Left to automatic devices - like detectors and fusible links - the audience should be out before any of those things operate - with a factor of 3.

Large - performing arts - stage fires are rare. I'd suggest that if the fire were so bad that they hesitated to enter, than they would simply try to protect adjacent property and let the stage go.

The vents help substantially with keeping smoke out of the audience and on a tall stage simply keep the neutral pressure plane above the proscenium opening so no smoke enters the house. They are there to protect the audience, not protect stage occupants.

I am afraid that if we ever have a real stage fire and the lobby has been designed as an atrium with atrium exhaust, that it may suck smoke from the stage into the house and lobby, but I'm tired or reacting to the last emergency and looking to plan for the next.

It's often on stage sprinklers that automatically activate the deluge, not the other way around. Manual activation of course is possible.

 

[SteveB]

I am afraid that if we ever have a real stage fire and the lobby has been designed as an atrium with atrium exhaust, that it may suck smoke from the stage into the house and lobby, but I'm tired or reacting to the last emergency and looking to plan for the next.

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I'm aware that our fire detection and alarm system as a couple of function, including activating the generator, activates the stage tower powered vent system, as well as shuts off power to other building vent systems so as to prevent smoke from being vented throughout the building. Does it all work ?......