Minimum distance from walls
Minimum distance from walls
(OP)
The 2007 NFPA 13.8.6.3.3 says that sprinklers shall be located a minimum of 4" (102mm) from a wall.
My state's architect responsible for Life Safety has said that his interpretation of this is that the deflector must be at least 4" from the wall. Based upon the width of different sprinkler deflectors that can move the center point of your sprinklers some distance one way or the other.
I've discussed the same issue with one of the "ask the expert" folks who disagrees with this interpretation. His take on it was that based upon figure 8.6.4.1.1.3 the distance is to be measured from the wall to the center of the sprinkler.
I tend to agree with the architect's interpretation as the code says "sprinklers" must be a minimum of 4" from a wall, not the "center of a sprinkler" or "a sprinkler's element."
What say you?
My state's architect responsible for Life Safety has said that his interpretation of this is that the deflector must be at least 4" from the wall. Based upon the width of different sprinkler deflectors that can move the center point of your sprinklers some distance one way or the other.
I've discussed the same issue with one of the "ask the expert" folks who disagrees with this interpretation. His take on it was that based upon figure 8.6.4.1.1.3 the distance is to be measured from the wall to the center of the sprinkler.
I tend to agree with the architect's interpretation as the code says "sprinklers" must be a minimum of 4" from a wall, not the "center of a sprinkler" or "a sprinkler's element."
What say you?





RE: Minimum distance from walls
However, I've never really questioned as to how the dimension is measured so I look forward to other opinions.
RE: Minimum distance from walls
RE: Minimum distance from walls
The purpose of this requirement is to allow for a proper development of a spray pattern and not so that it can respond to fire gases captured at the ceiling.
NFPA 13 indicates that the distance from the wall to the sprinkler shall be measured perpendicular to the wall.
It does not says anything about being measure from the side, front, top, etc of the sprinklers.
However it only makes sense to measure from the center to avoid writing multiple codes based on the many different sizes of deflectors in the industry.
Also, if the distance between sprinklers shall be based on the centerline between sprinklers then it also makes sense to apply same rule to distance from walls.
RE: Minimum distance from walls
I would say the 4" is to the center of the head. Even with an extended coverage head the deflector isn't going to be more than 2". If you are designing / installing them with that tight of a tolerance to a wall you are just asking for trouble.
RE: Minimum distance from walls
RE: Minimum distance from walls
Huh.. I also thought the minimum 4" was there so that it wouldn't affect the spray, due to 'backsplash effect' (for lack of a better term) screwing up that heads spray pattern and throw distance in the direction away from the wall.
I thought Ron Cote's advisory notes in the 13 handbook stated as such, but it also makes absolute perfect sense about the heat plume..
That is very analogous to the passages from NFPA 72 that prohibit heat detectors from being located in the same "corner" of thermal dead space.
RE: Minimum distance from walls
Think about dust, hair-balls and even spider webs......these accumulations are commonly found in the corners at the ceiling level and on floors due to limited air flow in the transition between a vertical wall and a horizontal ceiling. There is some law or effect named after the man who identified and documented this phenomenon; however, I do not remember hs name (Darcy maybe??).
Stookey is correct (based on my opinion and limited knowledge in this matter).......the primmary reason behind the 4 in. requirement is to prevent delayed aprinkler activation.
After the sprinkler operates, why would it matter if the water hits a vertical wall just 1-2 in. away from the sprinkler?? Everything within the protected circle or sprinkler umbrella pattern will still get wet (as long as there are no other obstruction issues of course!).
Most sidewall sprinklers also must be installed between 4-6 in. below the ceiling due to this corner issue (this requirement also allows the spray pattern of the sidewall sprinkler to develop properly; water throws slightly upward prior to the effects of gravity causing the downward fall).
Now back to the original question.......install all sprinkler deflectors >4in. from the wall and/or measure from the deflector to the wall and the point is mute. The more conservative approach is usually better when dealing with NFPA requirements; this way individual opinions (i.e. lawyers or professional witnesses in court) do not matter.
RE: Minimum distance from walls
NFPA 13-2002
Chapter 8-Installations Requirements
Section 8.5-Position, Location, Spacing and use of Sprinklers
8.5.1.2
Sprinklers shall be positioned to provide protection of the area consistent with the overall objectives of this standard by controlling the position and allowable area of coverage for each sprinklers.(it only speaks about the proper coverage)
8.6.3.2.2
The distance from the wall to the sprinkler shall be measure perpendicular to the wall.
8.6.3.3
Sprinklers shall be located a minimum of 4" from a wall
I believe stookey's comment could refer to sprinklers located too close to ceilings rather than walls.
RE: Minimum distance from walls
I don't think I've ever seen a sprinkler that close to a wall. I think it would only happen if someone were to build a wall next to an existing sprinkler.
RE: Minimum distance from walls
RE: Minimum distance from walls
This made me laugh out loud. If stookey posted that NFPA called for sprinklers to be installed in cars I'd be designing car sprinkler systems later that day.
RE: Minimum distance from walls
I would consider the bulb/link to be the detector, and not the frame of the sprinkler.
RE: Minimum distance from walls
RE: Minimum distance from walls