Obstruction to Discharge !!! 1

[MedullaOblongata]

Is there any NFPA 13 code section I can refer to avoid sprinkler heads underneath the sunshade? (Please see attached sketch)
A room, 11’-0” ceiling height, light hazard occupancy has aluminum sunshade in the window. The sunshade is 3’-10” below the ceiling and extends 2’-11” into the room from the window. NFPA 13 2010 Section 8.6.5.3.3 states, sprinkler shall be installed under fixed obstructions over 4ft. Can any of the sections be applied to avoid sprinklers underneath the shade?
The maximum allowable distance of deflector above the bottom of obstruction per table 8.6.5.1.2 is 35 in. The distance from the ceiling to the sunshade is 46 in. also “D” in Fig. 8.6.5.1.2(b) is greater than 30” so I can’t apply thee basic obstruction rules.

 

[cdafd]

Move the head away from the wall so it gets water under the shade

Should not be a big design issue

 

[pipesnpumps]

I see your dilemna. Can't treat as a soffit (>30"), can't use beam rule (>18" below deflector) if you were seeking credit for 'spraying under' the sunshade.

However, I would say it doesn't need additional heads because the shades are not >48" wide. See 8.6.5.3 "Obstructions that Prevent Sprinkler Discharge From Reaching the Hazard". That is the section that applies in my opinion. Think of the shade as a cable tray or duct. You wouldn't put heads under a 2'11" wide duct. An AHJ might fight you on that, though because water can't pass over the shade only under it, and only under if the head is ~11' from the wall (see figure A.8.5.5.1) need 8' distance to throw under something 4' below the head. If you placed it carefully and did that, they'd really be out of line not allowing it.

As it stands you could plausibly claim 2'11"<4'0" so no sprinklers are required.

Real world knowledge doesn't fall out of the sky on a parachute, but rather is gained in small increments during moments of panic or curiosity.

 

[MedullaOblongata]

Thanks cdafd & pipesnpumps. The heads can be moved away from the shade to spray underneath it... but cant maintain the 7'-6" max. distance from the wall to the head. Design is based on standard pendent spray heads.
The light shelf need to be reduced to 16" max. depth to remain at the current elevation or else the elevation will have to be increased.

 

[cdafd]

I am thinking that if you max out the head, you should be good to go

Will look at the book to see if there is something

Can you use small room rule or is room to big???

Or use extended coverage head???

Need to look at the book may be a non issue

Will get back

 

[MedullaOblongata]

Trying to avoid using extended coverage heads. Its and office space. Thanks !

 

[SprinklerDesigner2]

Who hasn't wrestled with something like this? What difference would it make if the sunshade were a duct?

The question is "Does NFPA 13 require every square inch or square foot of floor space to be physically wetted by spray from a sprinkler?"

Attached is an interesting answer by Ken Isman

https://www.sfpeatlanta.org/downloads/conference_2011/seminar3_sprinkler_seminar.pdf

contained in the March/April 2005 TechNotes.

 

[cdafd]

OK
going by the reference you stated """Section 8.6.5.3.3 states, sprinkler shall be installed under fixed obstructions over 4ft.""


Unless I am missing something the shade is only 2'11" inside the room

so no problem!!!!!!!!!!!

 

[MedullaOblongata]

Thanks SprinklerDesigner2 and cdafd... I will stick to the "Duct Rule".

 

[cdafd]

Looks like pipe and pump was the first to see that there is no problem.