NFPA 13 - Highly Sloped Ceiling/Wall & Ordinary Hazard Sidewall Sprinkler

[plumbingandfiredesgn]

Hello, I'm looking to use sidewall sprinklers for a heavily sloped skylight funnel (large enough that it needs to be covered by sprinklers). The slope of the funnel walls are something close to 177:100.

This is an ordinary hazard occupancy.

In NFPA 13, 2019, section 10.3.2, they specify that sidewall sprinklers shall only be installed in:
- Light hazard occupancies with smooth, horizontal or sloped, flat ceilings
- Ordinary hazard occupancies with smooth, flat ceilings where specifically listed for such use

I'm a little confused by this wording - smooth & flat don't exactly indicate if pitch is involved. They specified "horizontal or sloped" in light hazard, but brought no mention of either in ordinary hazard. I would have expected "horizontal" to be used in ordinary hazard if that was the intent. Does anyone know how to approach this?

 

[MGXFP]

NFPA 13 defines horizontal as no more than 2:12 slope, sloped ceilings are more than 2:12 slope. Flat just means a continuous plane. Generally, if the slope exceeds 2:12, you are limited to placing the sidewall sprinklers at the top and aiming them down the slope with the deflectors parallel to the slope of the ceiling. You will probably need to use upright sprinklers for this application.

 

[plumbingandfiredesgn]

Thank you MGXFP. Are you suggesting upright sprinklers for a particular reason, instead of the sidewall sprinklers aimed along the slope?

 

[cdafd]

Always look at the specific listing / manufacture sheet for the sprinkler you are going to use.

See any listing restrictions,,,, like light hazard only

Or smooth ceiling

If you want to install per listing and nfpa 13

Sidewalls are the most abused sprinklers.

Like this one::;

https://www.manualslib.com/manual/3372073/Tyco-Grinnell-Fr-1.html?page=5#manual

m) orifice, Model FR-1HorizontalSidewallSprinklersmustonly be installedand utilizedin LightHazardOccupancies,undersmoothceilingsand in accordancewith thecriteriagiven in Table A-lor A-2, asapplicable.The

 

[TravisMack]

You can only put sidewall sprinklers at the peak shooting down the slope. You can't use them along the side aimed along the slope.


Travis Mack, SET, RME-G,
MEPCad, Inc
AutoSPRINK | AutoSPRINK FAB | AutoSPRINK RVT

 

[MGXFP]

As cdafd and Travis said, you cannot have sidewalls spray perpendicular to the slope when the slope exceeds 2:12 unless the sprinkler is listed for that and I know of no sprinkler listed for this use. I believe it is because a fire plume will bypass the sprinkler due to the placement of the sprinkler in the area where the wall and ceiling join where the gas dynamics create a solenoid effect. Standard spray uprights and pendents are quite universal in applications like what you have described and are probably your main option.

 

[plumbingandfiredesgn]

Thank you all for the help! The gas dynamics at the corner are a great point I hadn't considered at all. I'll be sticking to some pendants in this case.