I'm an architect and have been trained that the spray from a sprinkler head must touch the walls of a room leaving no gaps in coverage. I understand for light hazard one sprinkler head can cover 130 to 200SF. My question is, if you have one standard sprinkler head in a room that is 12'x16' (192 SF) and you center the head in the middle of room, the spray won't hit the walls; the corner condition won't be covered. Is that ok? I
Thanks Michal. Can you tell me why that's ok? I can't find a reference to this in NFPA.
I'll find you this chapter. But tomorrow it's 1 AM here in Poland. Going to sleep
What I have now it's a rule when you draw a grid, distance to wall is half the distance between sprinklers. Following this rule you will always have your corners unsprinklered. Till tomorrow Jennifer I'll find it for you!
Jennifer
NFPA 13 gives us guidelines for sprinkler spacing based on the occupancy see the attached for light hazard.
you are ok.
No such requirement. Here are some tools for you to use for basic design. Its up to the professional licensed sprinkler designer to finalize the design drawings and specifications.
https://www.archtoolbox.com/materials-systems/fire-supression/sprinklerspacing.html
According this guidance you should be able to protect the room with one sprinkler head.
I think if you do the research you will find that a standard coverage sprinkler in light hazard san never exceed 225 sq feet so you would need a extend coverage to do a 16 x 12 room
While everyone is close, no one is correct so far. One standard spray sprinkler in light hazard will cover 225 Sq. ft. max. A room 16'x12' is 192 Sq. ft. so it will cover this room. However, if the sprinkler is placed directly in the middle of the room it does not meet NFPA requirements. You can use the small room rule as Anthony suggests, BUT you will need to shift the sprinkler along the 16' wall so that it is 8'-6" from one wall and 7'-6" from the opposite wall. With the small room rule you can only be UP TO 9'-0" off any SINGLE wall. Not multiple walls. Max distance to any other wall is 7'-6"
Also, the only time you measure to a corner is if the walls are angled. The max distance to this type of corner is 11'-3", but you must maintain the 7'-6" max distance from a wall. Distance from sprinklers to walls are always measured in a perpendicular fashion.
Thank you everyone! This has been really helpful in educating the architect:)
As an architect, you are probably not hydraulically calculating the fire sprinkler system to prove that the one head in a small can used.
Milton noted "Its up to the professional licensed sprinkler designer to finalize the design drawings and specifications."
Anthony gave you the correct code section.
Tom gave you some actual dimensions which are correct but most likely not give a center of tile or pleasing ceiling layout. But in any case the spacing per sprinkler can not exceed 225 Sq Ft. Which relates to a maximum distance along the 12'-0" wall of 6'-7"
Hydraulically double each dimension 17 x 13.25 = 225 Sq Ft for light hazard you will need to provide 22.5 gpm for each sprinkler that is in the small rooms. If the open office space out side these offices is a maximum of 14x14=196 Sq Ft or 19.6 gpm for each sprinkler. We find that the most common open office spacing using standard sprinkler is 12 x 14 = 168 Sq Ft or 16.8 GPM.
So there may be additional water required when using this small room clause.
You don't use SxL in small room. So you can be 7'-6" along the 12' wall. In small room, you take the area of the room divided by the number of heads.
There seems to be a couple different code sections.
The original question is about code section 13:8.6.3.2.4.1. and Appendix A13:8.6.3.2.4. This would allow a maximum room size of 247.5 Sq Ft.
I also refer to 13:8.6.3.2.4.2. This section states the maximum room size to 225 Sq Ft.
What I don't find in chapter 8 or 11, is where it states that you don't need to double the distance from the walls when hydraulically calculating the heads and that you only need to use the Sq Ft of the room.
Please direct us to that code section. This would be very helpful.
8.6.2.1 Determination of Protection Area of Coverage.
8.6.2.1.1 Except as permitted by 8.6.2.1.2, the protection
area of coverage per sprinkler (As) shall be determined in
accordance with 8.5.2.1.
8.6.2.1.2 The requirements of 8.6.2.1.1 shall not apply in a
small room as defined in 3.3.22.
8.6.2.1.2.1 The protection area of coverage for each sprinkler
in the small room shall be the area of the room divided by
the number of sprinklers in the room.
I agree on multiple heads in a room.
David Hague of NFPA wrote: "When using the small room rule, a single sprinkler can be installed in a room that is no longer than 16'-6" in length PROVIDED that the width of the room does not exceed 15'-0". In this instance, the sprinkler can be located as much as 9'-0" from one wall but not more than 7'-6" from the opposite wall and it must be centered in the 15'-0" direction. For rooms exceeding 16'-6" in length, multiple sprinklers must be used as shown in Figures A.8.6.3.2.4(b), (c) & (d)." and "In response to your follow up question, sprinklers are permitted to be located not more than 9'-0" off a wall provided that they do not exceed one half the maximum distance off the opposite wall and the average spacing of all sprinklers in the room does not exceed that specified in Table 8.6.2.2.1. In your example, a room with an area of 742.5 ft2 would require 4 sprinklers."
Thanks for your input. This is a good conversation.
yes it's ok for corners.