How to Adequately Sprinkler Suspended Art?

3/27/2023

I am currently working with a few artists that want to build an installation in the lobby of a high-rise office building.

Their design includes hanging acrylic bats independently hung from wires from the ceiling at varying heights to represent a bat swarm. What started as “a couple hundred bats, 6-8 inches in size, spaced evenly throughout the lobby” has turned into 1,300 bats, up to 12 inches wide, in a fairly dense swarm.

The artists and interior designers submitted this design to the AHJ without providing a final design or correspondence and were rejected (no surprise.) The rejection was based on the swarm obstructed both by being within 2 feet of the head, and the density of the bats.

Additionally they are worried about the flammability of the bats and want them tested per NFPA 289 to make sure the amount of acrylic has a heat release rate of less than 100 KW.

My questions here are two-fold:

1) How would one properly protect, or space these bats, so that sprinkler protection is not an issue?

At what density would hanging items like these turn into an obstruction, and once they are considered an obstruction, would the only way to solve the issue be to sprinkler both above and below the swarm?

2) Has anyone ever worked with NFPA 289?

I have been looking for information on heat release rate of acrylic or any plastic in general, who would test items to the NFPA 289 standard?

Or is there any information on how to properly categorize this hazard and determine if the heat release rate is less than 100 KW?

Looking forward to any thoughts. Thanks.

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18 Comments

Glenn Berger

3/27/2023 08:08:14 am

I have no experience with NFPA 289, but I have had a similar experience.

I worked with the AHJ with a recommendation of provided projected beam smoke detection below the obstruction level. This solution was accepted and when the obstruction was removed the smoke detection system was removed.

Schulman

3/27/2023 08:12:01 am

Sounds awesome.
It does not take much to create an obstruction - think about grating or walkways above theaters with grating ... usually required above and below ... I have worked on some cool ceilings in my day .. all required above and below coverage ... good luck.

Dan Wilder

3/27/2023 08:23:20 am

Independent testing is going to be time consuming and exspensive. Any option to place them on a link release for what I am assuming is the cable supports that support these units?

Check out your local Museum/Art Expo halls and find out what they provide for density, area, and sprinkler types (some modified design density approach), those have similar obstruction exhibits. You can also get an FPE involved to come up with a AM&M approach with some heat release calculations and design approaches.

Jesse

3/27/2023 08:28:59 am

Well this one's a mess isn' it.

Agree with Dan about the timeliness about testing. I'd be surprised if you had actionable results in 6 months. I like Dan's link idea.

My 2 cents, these present an obstruction to AS discharge.

Casey Milhorn

3/27/2023 09:07:00 am

Is this going in the new Wayne Industries HQ? I think the original was blown up, so probably good idea to sprinkler it. I would go with an OH2 for the whole building, at the very least.

Sorry, couldn't help myself.... lol.

But in all seriousness, I agree on the involvement of a FPE. If you are a contractor, you don't want to make the call on this one.

BUT, I would think an increased density at the ceiling, closer spacing of heads, along with requiring X percent to be open by total horizontal area would be a good start. Activation time and coverage.

Anthony

3/28/2023 07:57:34 am

Came here to make this joke, great job.

M. Newell

3/27/2023 09:29:27 am

I have seen instances where they have protected areas like this as EH-2. They in theory said the application was comparable to a heavily shielded fire. It could be one option you look at offering to the AHJ/Design Team. Since it would cover high heat release fires, and shielding so two-birds one-stone method. IMHO.

Franck

3/27/2023 11:44:33 am

One practical question: is there something to burn underneath ?

The fact that it is 2 feet below the sprinkler is fine (as with standard sprinklers you need 36 in. between sprinkler and top of storage).

If the bats are burning, you will cover them with the sprinklers.
And if there is nothing to burn underneath... well, in that case, the sprinkler protection is not really needed under the obstruction created by the bats.

I don't see a possible quick spreading fire (that could overtax the sprinkler protection, as it is not combustible dust deposit, but quite large objects).

In addition, as bats are hung by a wire, it also means that the water discharge will probably wet adjacent non burning bats and remove them (pushed by water) from the burning ones.
As long as the bats are not attached to sprinkler piping!
I would be more concerned with life bats flying all over the place and distributing the fire through multiple ignition sources :)

Increasing the sprinkler density in an existing situation is quite complex, and by the time you did it, the exhibit is gone (and while you do it, you still have the problem and no fire protection at all !).

Comment from Glen si quite fair. provide temporary beam detection below the bats. Sprinklers above for fire on the bats. Smoke detection below fo anything that could happen underneath.

But this is my personal opinion, not to be considered as what the AHJ would say or accept.

3/27/2023 11:49:29 am

In addition to my above comments, one of my concerns in your situation, is not that the heat release will be tremendous (you have many bats, but this is not plastic storage in racks over 20 ft), but on the contrary that the bats will burn, but heat release will not be sufficient to operate the sprinklers, and the fire will gently spread throughout all your bats, without any sprinkler operating.

The good thing is : there should be limited ignition sources over there, so limited probablility to have a fire (even though the consequence would be the same... if it happens anyway).

Shawn G.

3/27/2023 12:17:01 pm

FM has approaches that deal with grouped obstructions. These bats don't really fit nicely into that criteria, but it could provide some guidance to assist you in finding an answer to your first question.

Dave

3/27/2023 12:35:49 pm

What does the cauldron look like in plan / RCP view? Are they throughout the lobby?

3/27/2023 12:39:31 pm

...I guess what I'm wondering, is it roughly solid as the parameters of the two elevation views above indicate?

Jerry Clark

3/27/2023 12:40:00 pm

Just dealt with a similar issue involving acrylic spheres used as a center feature with lights powered by stationary bikes. Referred to Chapter 26 of the IBC which covers plastics. Most of the chapter deals specifically with plastic used as architectural features versus artwork. But Section 2606.4 is specific to self-ignition temps, smoke development ratings, with direct reference to testing standards:

2606.4 Specifications
Light-transmitting plastics, including thermoplastic, thermosetting or reinforced thermosetting plastic material, shall have a self-ignition temperature of 650°F (343°C) or greater where tested in accordance with ASTM D1929; a smoke-developed index not greater than 450 where tested in the manner intended for use in accordance with ASTM E84 or UL 723, or a maximum average smoke density rating not greater than 75 where tested in the thickness intended for use in accordance with ASTM D2843 and shall conform to one of the following combustibility classifications:

Class CC1: Plastic materials that have a burning extent of 1 inch (25 mm) or less where tested at a nominal thickness of 0.060 inch (1.5 mm), or in the thickness intended for use, in accordance with ASTM D635.

Class CC2: Plastic materials that have a burning rate of 21/2 inches per minute (1.06 mm/s) or less where tested at a nominal thickness of 0.060 inch (1.5 mm), or in the thickness intended for use, in accordance with ASTM D635.

Pete H

3/27/2023 01:25:57 pm

2) Nope. Never.

1) Decide every clump of bats is a duct. Never let the clumps exceed 4'-0" wide without some spacing between them and the next clump of bats. If they exceed 4'-0" wide, spray underneath the hanging obstruction.

Make sure there is an 18" clearance between the top of bats and the deflector of your sprinklers.

For unnecessary fun: Drop exposed pendent sprinklers in the middle of clumps of bats and add Bat-wings to the frame arms.

Don Pierce link

3/27/2023 03:53:39 pm

I have had scenarios such as this come up multiple times. Often the "architectural feature" is in an atrium and not only poses an obstruction to sprinklers getting to the fire but adversely affects the smoke control system activation. It is a domino effect. Delayed sprinkler activation and mechanical smoke ventilation increased temperatures that were not survivable at the upper floors. Dan Wilder gives good advice. Get a FPE for an AMM. Unfortunately liability drives most decisions. This is one of them.

Pete D.

3/27/2023 07:49:05 pm

I just wanted to quickly provide my in-depth professional assessment, that this seems like something an interior designer would submit to an AHJ.

Street

3/29/2023 09:55:08 am

Spot on

Sean

3/31/2023 11:27:10 am

I think that without further information or justification I would consider it an obstruction.

How to Adequately Sprinkler Suspended Art?

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