Smoke Vents - article

[MPowers]

I don't know, maybe this would be better as a Wiki entry, but here it is. A lot of people ask me about Smoke Vents, When do you need them, why, what's the code? Bill Conner wrote a nice article that's in this summer issue of Protocol about them that should answer a lot of questions. View attachment Stage Ventilation.pdf Or, here is a link to the article in the magizine.

Go to page 48.
Protocol - Summer 2013 digital edition

 

[ruinexplorer]

It is the second one listed in this post. Protocol is a wonderful resource for our industry! Great job Bill.

 

[gafftaper]

Moved to the Safety forum. Offtopic is not visible to non-members and isn't searchable via Google.

 

[zmb]

Moved to the Safety forum. Offtopic is not visible to non-members and isn't searchable via Google.

I thought the safety form was members-only and non-searchable by Google too?

 

[dvsDave]

Nope, only the Off-Topic Forum. A previous iteration of the safety forum was non-searchable, but that concept was killed.

That's a great article, written by none other than our very own BillConnerASTC.

What makes me laugh about this is that I had a member of our music team pulled me aside yesterday morning at the school our church meets at to point up at the ceiling of the stage to ask me what on earth that opening in the ceiling was. Up until that point, I had never noticed that it was there. I googled what it could be and ran across Bill's article yesterday. Funny how that sort of thing happens!

 

[StradivariusBone]

Our space has five doors that are operated by manual release pull cables located on the upstage wall and I'm wondering if it would require a trip to the roof to close them. I'd like to test them since during a fire is a bad time to find out it they actually work, but I'd rather know I can get them shut before going down that road and exposing my flyspace to the elements.

Any advice on investigating this?

 

[BillConnerFASTC]

Without a winch, my experience suggests that you may need to get on the roof to close most of these - and might require two people if large and newish since the springs are strong to overcome snow and ice. Very hard to pull close from inside by hand but not impossible.

Is the up stage operator a simple release or is there a winch? If a winch, then you should be able to open and close them as required for testing. If just an extended pull release, then up to the roof you go.

Picture? Maybe I can help more.

 

[StradivariusBone]

We're in sunny Florida here, I think if we ever experienced snow and ice we'd have larger problems than fire vents not opening!

I've attached a picture of the release mechanism (there's five, one of which has a lot more slack in the wire rope than the others) and a photo of the door from the inside. We don't have a grid and getting on the roof is a bit of a chore as the roof access to the fly space is in a loft above the dressing rooms with the only access being a genie lift or ladder.

The picture is rough, but it looks to me like the wire rope pull might just unlatch a release of some kind, so I was guessing it would require someone pushing it closed from above. It'd be nice to learn how to since the releases are not protected from ne'er do well high schoolers who might happen upon them.

 

[SteveB]

Without a winch, my experience suggests that you may need to get on the roof to close most of these - and might require two people if large and newish since the springs are strong to overcome snow and ice. Very hard to pull close from inside by hand but not impossible.

.

Some better designed systems have a method to winch them closed. Ours do not.

With ours, it's more like 4 people standing on top of ea. door, 8 doors total. They need to be closed as a pair, so 6-8 people required.

This is mostly due to the strength of the pistons that pop the doors. Our doors as well, have a surface metal that resembles the "Spirit of St. Louis" Lindbergh plane, so a highly polished metal. Treacherous to stand on in the rain/snow.

You can reset the doors only after resetting the power to the mechanism to re-set the magnetic release latch. We discovered this after much trial and error.

Our system opened one night mid-show, when the smoke detector sensed too much theatrical smoke. It was raining, then snowing and we literally had to wait till after the dance company load out before climbing to the roof. Then 8 people climb on top, hoping to not slip and fall the 20 feet thru the roof and onto the gridiron.

After this incident we removed the smoke detector, code be damned.

They subsequently installed a powered roof venting system, on a generator, that is supposed to render the roof doors obsolete, which is a good thing due to what had been three total systems in our facility, that have triggered a total of 6 times over the past 10 years or so. We now call our Public Safety and Facilities Departments and refuse to deal with them.

 

[BillConnerFASTC]

Strad - the "right" answer for yours is probably to install the Thern Smoke Vent winch and connect to the fire alarm - which simply actuates and electro thermal link which releases the winch. You can still immediately close them.

Steve B - NYC is a whole different world for codes so not commenting. The problem with mechanical exhaust is the requirement in standard to provide make up air, Lots of holes to the outside that open automatically when the vent tells it to. Not easy.

The "best" answer for new build is the electric winch option.

Unfortunately neither "right" nor "best" is inexpensive.

 

[SteveB]

Steve B - NYC is a whole different world for codes so not commenting. The problem with mechanical exhaust is the requirement in standard to provide make up air, Lots of holes to the outside that open automatically when the vent tells it to. Not easy.

The "best" answer for new build is the electric winch option.

Unfortunately neither "right" nor "best" is inexpensive.

NYC changed it code way back in the mid-70's to allow an alternative to roof-top smoke doors, the alternative is a powered venting system on a generator.

The over-riding reason for the change was money. Real estate developers were looking at the wasted space over all those Broadway theaters and wanted to build vertical. The need for a roof door venting system prevented that. Thus the powered vent system was developed to allow a theater to be placed inside an office tower. Many new theaters got build as a result, including a few in the "off-Broadway" and Off-Off market, American Place Theatre, Uris/Gershwin, Marriot Marquis, among others, so possibly this wasn't a bad thing.

We are now in discussion with the architects and consultants doing a fire/safety system upgrade to get them to officially de-activate our 2 remaining roof door vent system.

 

[StradivariusBone]

Strad - the "right" answer for yours is probably to install the Thern Smoke Vent winch and connect to the fire alarm - which simply actuates and electro thermal link which releases the winch. You can still immediately close them.

It's funny how things work out- I just found out yesterday that our district is on a big life safety kick and I was told yesterday to expect a visit from some fine gentlemen associated with the AHJ who will be inspecting our venue and also beginning the procedure to install winch operated fire vents (not motorized, but I'm still happy I don't have to find 3 other guys to climb on a roof with me and hopefully not fall into the flyspace).

Thanks for the info, Bill!

-ED

 

[teqniqal]

For those that are interested, the NFPA 204 Standard for Smoke and Heat Venting is a good resource to have on-hand if you have a facility with Smoke Vents. In the Standard you will find that the Smoke Vents should be Inspected periodically. I frequently find Smoke Vents that have not been operated / exercised in their entire existence. When you pull on the handle to release them you find that they are stuck and will not open. This is either the latch itself that is immovable, or, if the latch releases, then it it the doors that are 'glued' shut due the weatherstripping melting in the baking sun.

Make sure that your latches are properly lubricated to move freely, and that the doors are opened frequently enough to ensure that they are not 'stuck' in the closed position.

Another item I see botched on the Smoke Vent installations is the routing and muling of the release cables. I see them take 90 degree turns over the edges of beams, and sliding along air ducts gradually sawing them in half. In short, the cable isn't rigged with deflection pulleys, it is just threaded through and around the building structure.

For whatever reason, many AHJ's don't appear to understand these systems, and they don't inspect or test them. They just look to see if they are present.

With regard to the Thern Smoke Vent winch, you can use a resettable electro-thermal link in lieu of a pyrotecnic (non-reusable) electro-thermal link and this makes resetting the system much simpler after a fire alarm system test. Of course, you can use these for the electro-thermal link that may be in-line with your Fire Curtain perimeter release line, too.

 

[MPowers]

.................With regard to the Thern Smoke Vent winch, you can use a resettable electro-thermal link in lieu of a pyrotecnic (non-reusable) electro-thermal link .............

Erich, Thern supplies the pyro version with the winches, but I would like to recommend the "resettable" device if it is cost effective and of course physically compatible. The devices I am aware of are roughly twice the cost of the pyro version, i.e. $300 vs: $150 each. Do you know of a cess expensive version? Do you like the McCabe resettable links? What brand do you recommend? Do you have a source?

 

[firewater88]

Some better designed systems have a method to winch them closed. Ours do not.

With ours, it's more like 4 people standing on top of ea. door, 8 doors total. They need to be closed as a pair, so 6-8 people required.

This is mostly due to the strength of the pistons that pop the doors. Our doors as well, have a surface metal that resembles the "Spirit of St. Louis" Lindbergh plane, so a highly polished metal. Treacherous to stand on in the rain/snow.

You can reset the doors only after resetting the power to the mechanism to re-set the magnetic release latch. We discovered this after much trial and error.

Our system opened one night mid-show, when the smoke detector sensed too much theatrical smoke. It was raining, then snowing and we literally had to wait till after the dance company load out before climbing to the roof. Then 8 people climb on top, hoping to not slip and fall the 20 feet thru the roof and onto the gridiron.

After this incident we removed the smoke detector, code be damned.

They subsequently installed a powered roof venting system, on a generator, that is supposed to render the roof doors obsolete, which is a good thing due to what had been three total systems in our facility, that have triggered a total of 6 times over the past 10 years or so. We now call our Public Safety and Facilities Departments and refuse to deal with them.

Sounds a lot like mine. I can do it by my self, but as you said, if weather is a factor, then I require two or more as a safety so i don't fall the 20 some feet to the grid. Mine were set to such a hair trigger that when the wind would cut across the fly tower, they would shake and then pop open. Of course they do it at the most in opportune time. Once during a local symphony show- I had so many complaints from the musicians from the draft that it has now created. And once over a long weekend, which then rained on stage all weekend, really cupping my floor bad. With a few slight adjustments, they don't do that anymore.
Mine are all mechanical and not tied into the fire alarm system, although reading here that some can be powered, I like that idea a lot better. But I just have to deal with what I got for now...

 

[carproelsofly]

I'm in a 300-seat theater in a 25-year-old building, with aggregate stage/wing/forestage area of over 1000 square feet. There are no smoke pockets in my room.

Any chance we're grandfathered under the 1987 code? Or just plain out of compliance?

Another theater in the same building has them....

Thanks,
Jen

 

[SteveB]

I'm in a 300-seat theater in a 25-year-old building, with aggregate stage/wing/forestage area of over 1000 square feet. There are no smoke pockets in my room.

Any chance we're grandfathered under the 1987 code? Or just plain out of compliance?

Another theater in the same building has them....

Thanks,
Jen

Maybe you are opening up a can of worms ?.

 

[BillConnerFASTC]

It would take some research time to determine what was required at the time your theatre was designed and given a building permit. Possible it is grandfathered.

 

[carproelsofly]

Thanks, Bill - I'll look into it!

 

[brownnathanial]

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.