Your experience with "melt away" drop in ceiling tiles designed to be installed below spri

[SprinklerDesigner2]

Just started exploring and the more I read the more questions I have.

To be specific I am looking at Ceilume's approved drop-out ceiling panels can be installed beneath fire sprinklers.

What is really disconcerting is there's some on the market that are marketed to be installed below ceilings but I couldn't find the UL or FM Mark on anything.

I got a feeling I could run into a real problem in a Light Hazard restaurant seating area where quick response sprinklers are required but the ceilings delay the response times? Could I end up with something where I could only use these tiles in Ordinary Hazard areas and if I do I would not be able to use the area reduction in areas that have a ceiling not exceeding 20'?

To be clear I am using the term "ceiling" to refer to the actual roof above the suspended ceiling not the drop in ceiling.

Also, unless I am reading it wrong which I sometimes do, the specific head has to be listed for use above these drop out ceilings?

I would appreciate any actual experience or input you may have.

 

[cdafd]

It has been 30 years since I have seen a drop out used. Does that count.

Appears the two RJA reports say it pretty well, especially the second one.

It seems to say the tiles have to be listed for light hazard use.

Yes they should each be marked, so in the future there is no question, and when someone goes to Lowe’s and picks up the dollar ones, a person can tell the difference.

Would read over the RJA reports and follow them.

Not sure if the handbook gives much more guidance, will look

 

[SprinklerDesigner2]

What I want to see is the submittal sheets for the ceiling that specifically deals with the listing. So far I haven't seen any online.

 

[cdafd]

Maybe not made??? At least in the US?

Appears needs to meet this UL listing?

https://standardscatalog.ul.com/standards/en/outline_723s_3

 

[cdafd]

This seems to say per SW the tiles do not need an identifier::


5.0 IDENTIFICATION

https://www.ceilume.com/static/pdfs/ceilume-iapmo-5021.pdf

 

[cdafd]

2016 3.3.9

Commentary says

“Currently, the listings for these ceilings limit the installation to standard response sprinklers.

Not sure if 2019 changes anything

 

[SprinklerDesigner2]

Same thing in the 2013 commentary.

"A drop-out ceiling allows the installation of a false ceiling beneath an existing sprinkler system. Drop-out ceilings provide an alternative to relocating sprinklers beneath a new ceiling.

Drop-out ceilings are evaluated to verify that they do not contribute to fire growth and that they do not significantly delay the operation of the sprinkler system. Once installed, building owners must ensure that any ceiling panels replaced during the life of the system are of the same type originally installed. Currently, the listings for these ceilings limit the installation to standard-response sprinklers."

I guess I should have read the handbook commentary first but now I understand why so few have encountered drop out ceilings before. In 44 years I've never seen one.

Somewhat related here's another theoretical question. A dentist office is Light Hazard but if I design the system for OH-1 with spacing and density do I still have to use quick response sprinklers? Some might think this is a silly question but why are quick response sprinklers required in light hazard occupancies? Is it to compensate for the less density and greater spacing?

If I wanted to have a dentist office in an old warehouse with K16.8 SR sprinklers providing a density of .60 over 2,000 sq ft I couldn't do it until I replaced the K16.8 SR sprinklers with QR just because it is defined as light hazard? Can't do that but I can install a dry system that might have a 60 second or longer delay and that is fine?

For the record I'd never try defining a dentist office as OH-1 but I am curious as to why quick response in light hazard only?

 

[cdafd]

Way above my pay grade and rank,,

But back to the 2016 commentary, does A 8.3.3.1 commentary and FAQ, kind of answer your questions, not historical note.

 

[UFT12]

NFPA 13HB, ed. 2019 also carries the same comment, "Currently, the listings for these ceilings limit the installation to standard response sprinklers". However this is only informative. It does not mean that the user is discouraged to use quick response sprinklers above the drop-outs. 9.3.11.2 says quick response sprinklers shall not be used unless the drop-out tiles are listed for such use (e.g. combination with QR sprinklers). Your spec shows they are listed for use with quick response heads. I assume the RTI of the drop-outs is less that the one of the QR heads and therefore the heads do not need to be listed for such combination with the drop-out ceilings. But that remains my assumption because nobody issues their RTI values really.

As to why quick response sprinklers are used in light hazard occupancies, the NFPA 13HB has pretty good information about it. In short, LH are generally slow developing fires. They do not produce strong plumes as in the case of OH or EH. Since NFPA 13 is written based on life safety criteria it makes perfect sense to have a system operating as fast as possible with fairly small amounts of heat. It is not really the less density and cost savings of less sprinklers installed that drives the use of such sprinklers rather less smoke production, better visibility, less CO ppm in air (which can be lethal) for both people and firefighters. Density is only a consequence (benefit) being applied on the early stages.

As to your example about the dentist office, typically speaking, nobody could stop you using the K16 QR heads, at least theoretically. After all, 8.3.3.1 ed. 16, 9.4.3.1, ed 19 allows CMSA and even ESFRS (!!) for LH occupancies (well could be just a bunch of small offices in a warehouse). You may go ahead and drench the whole area with tons of water but that would be an overkill in both installation costs and water damages.

Hope that helps a bit.