Thank you so much for posting this, I’m a 2nd year apprentice in the union and our class is once a month but our instructor goes over stuff way too fast and I am a slow learner so this helps me a lot
I know this is a couple of years old, but I’m not understanding why there needs to be 4 sprinkler heads on each branch for the normal exposure example. I’m starting with the room 26.625’ left-to-right and 26.917’ top-to-bottom. It seems to me the way to enable the maximum sprinkler head spacing (S) is to minimize the branch spacing (L) since S = 130 / L (smaller L means larger S). The way to minimize L is to divide the room width by 2, which gives a branch spacing of 26.625’ / 2, so L = 13.3125’. Any smaller and the branch-to-wall distance times 2 would be larger and used instead for L. With an L of 13.3125’, the max sprinkler head spacing becomes 130 sq ft / 13.3125’, so max S = 9.765’. If I distribute 3 sprinkler heads along each branch, I can determine a good spacing by dividing that room dimension by 3. So 26.917’ / 3 means S = 8.972’, which is greater than the 6’ minimum spacing and less than the 9.765’ maximum spacing needed to stay within the 130 sq ft maximum area when the branch spacing is 13.3125’. Spacing from the first and last heads on a branch to their respective walls is 4.486’ (1/2 of S, so 8.972’ / 2). I’m not trying to pedantic, I’m really trying to understand and I’m not sure my math is correct or if there is something I’m not accounting for.
Thanks for the comment. And, no worries, I always assume people are genuinely trying to understand. A couple of notes: This is meant to be a simple introduction and there's many ways to lay out sprinklers (depending on several factors (out of the scope of this free video). There was also a harsh video cut at 15:11...which I realized several months after uploading the video =( I'm assuming, "normal exposure" you mean Ordinary Hazard (since you mention 130 - 130sf max per sprinkler). I think the confusion comes from your statement "minimize the branch spacing L". Actually, most of the time, you want to keep L (distance between branch lines) as large as possible so that you minimize the number of branches (fewer large fittings, etc.) (4:10 and 11:32). Hence the initial 14' separation (we want to keep 2 branches only). However, the distance between sprinklers cannot remain at 14' (like in the previous example for light hazard). So, I tried keeping that distance as 10'. However 130sf / 14ft = 9.286ft, so they cannot be spaced 10ft either, it has to be even smaller... Now, if you pause the video at 15:08, and remember the 9.286ft max distance... 9.286/2 = 4.643ft, and the distance from the wall is 4.578. So the top sprinkler would barely comply (again, assuming the video frame of time = 15:08). HOWEVER, if you move the south sprinklers up 2' (because remember, 10' between sprinklers is too much, so you have to shrink to 8'), then that distance of 4'-4 1/16" shown on frame 16:51 becomes 6'-4 1/16", which when multiplied by 2, exceeds the maximum distance along branch line. Just as a word of caution, even if the south sprinklers were at the same situation as the north sprinklers (barely making it), I, as a consulting engineer wouldn't keep it since the ceiling could shift 1 inch and then everything is out of compliance (not to mention any changes with lights, diffusers, detectors, etc.). (As a contractor you can push a little more, because by the time they get the project the project is a little more "solid"). I really hope this clarifies. Thanks for watching and good luck. Also, keep in mind that depending on workmanship, type of fittings and site conditions, it might be beneficial to "revert S and L", and remember, your layout has to be "balanced (symmetrical and pretty), so that Architects like you too =)
Should water temperature and room temperature be considered for efficiency...also should mix type of fire class like gas station out door fuel fire and foam ratio per area
Hi Eric. Water temperature and room temperature have no direct effect on the sprinkler spacing. Sprinkler spacing is a function of the "fire occupancy hazard". If you have a gas station you have a more demanding fire occupancy hazard than an office, so your sprinklers would have to be spaced closer together and you would be required to use a higher water discharge density (gpm/sf).
There are several factors that can affect that. The 1st one is Occupancy Hazard. If you are in a Light Hazard space, the maximum spacing is 15' and the maximum protection area allowed is 225sf. If you are in an Ordinary Hazard I, then max spacing is 15', but max area 130sf. There are also obstructions, etc. Check NFPA 13
Perfect mix of modern BIM approach and field experience. Thanks! Great job
Thank you Andrea
very clear, important and useful information, we are learning a lot with your videos Alex, Thanks
You are welcome Beatriz.
Great topic. Can't wait for #2. Thanks!
Well Daniel, stay tuned and buckle up =)
Amazing content as always!!!
Thanks for sharing.
Keep up the good work!
Thanks Stuard. I'm glad you liked it.
I understand now! the way you explained it and showed it was perfect
I'm glad it was useful and you liked it.
Great Alex!! thanks for your time
Hi Larry. I'm glad you enjoyed it.
Stay tuned for the pump room webinar, and sign up if you haven't =)
Great video! Very useful
Thank you Andreina. I'm glad you found it useful.
IT SEEM TO ME VERY INTERESTING
Stay tuned for more videos on this
Thanks Alex . Good presentation
Glad you liked it!
Nice video! I would be interested in the small room exceptions! Great job!
Hi Orlando. It's on the list. Stay tuned =)
Love it!
So glad!
Thank you so much for posting this, I’m a 2nd year apprentice in the union and our class is once a month but our instructor goes over stuff way too fast and I am a slow learner so this helps me a lot
Glad it was helpful!
Nice video!
Glad you enjoyed it
This Is great idea
Thanks Adel
Aha! I will use it to plan my RCPs
Great! Make sure to leave some work for MEP consultants...hope you don't know hydraulics lol =P
Thanks a lot!!!
You're welcome!
I know this is a couple of years old, but I’m not understanding why there needs to be 4 sprinkler heads on each branch for the normal exposure example. I’m starting with the room 26.625’ left-to-right and 26.917’ top-to-bottom.
It seems to me the way to enable the maximum sprinkler head spacing (S) is to minimize the branch spacing (L) since S = 130 / L (smaller L means larger S). The way to minimize L is to divide the room width by 2, which gives a branch spacing of 26.625’ / 2, so L = 13.3125’. Any smaller and the branch-to-wall distance times 2 would be larger and used instead for L.
With an L of 13.3125’, the max sprinkler head spacing becomes 130 sq ft / 13.3125’, so max S = 9.765’.
If I distribute 3 sprinkler heads along each branch, I can determine a good spacing by dividing that room dimension by 3. So 26.917’ / 3 means S = 8.972’, which is greater than the 6’ minimum spacing and less than the 9.765’ maximum spacing needed to stay within the 130 sq ft maximum area when the branch spacing is 13.3125’. Spacing from the first and last heads on a branch to their respective walls is 4.486’ (1/2 of S, so 8.972’ / 2).
I’m not trying to pedantic, I’m really trying to understand and I’m not sure my math is correct or if there is something I’m not accounting for.
Thanks for the comment.
And, no worries, I always assume people are genuinely trying to understand.
A couple of notes: This is meant to be a simple introduction and there's many ways to lay out sprinklers (depending on several factors (out of the scope of this free video). There was also a harsh video cut at 15:11...which I realized several months after uploading the video =(
I'm assuming, "normal exposure" you mean Ordinary Hazard (since you mention 130 - 130sf max per sprinkler).
I think the confusion comes from your statement "minimize the branch spacing L".
Actually, most of the time, you want to keep L (distance between branch lines) as large as possible so that you minimize the number of branches (fewer large fittings, etc.) (4:10 and 11:32). Hence the initial 14' separation (we want to keep 2 branches only). However, the distance between sprinklers cannot remain at 14' (like in the previous example for light hazard). So, I tried keeping that distance as 10'. However 130sf / 14ft = 9.286ft, so they cannot be spaced 10ft either, it has to be even smaller...
Now, if you pause the video at 15:08, and remember the 9.286ft max distance... 9.286/2 = 4.643ft, and the distance from the wall is 4.578. So the top sprinkler would barely comply (again, assuming the video frame of time = 15:08).
HOWEVER, if you move the south sprinklers up 2' (because remember, 10' between sprinklers is too much, so you have to shrink to 8'), then that distance of 4'-4 1/16" shown on frame 16:51 becomes 6'-4 1/16", which when multiplied by 2, exceeds the maximum distance along branch line.
Just as a word of caution, even if the south sprinklers were at the same situation as the north sprinklers (barely making it), I, as a consulting engineer wouldn't keep it since the ceiling could shift 1 inch and then everything is out of compliance (not to mention any changes with lights, diffusers, detectors, etc.).
(As a contractor you can push a little more, because by the time they get the project the project is a little more "solid").
I really hope this clarifies. Thanks for watching and good luck.
Also, keep in mind that depending on workmanship, type of fittings and site conditions, it might be beneficial to "revert S and L", and remember, your layout has to be "balanced (symmetrical and pretty), so that Architects like you too =)
thank you
You are welcome Pat!
Should water temperature and room temperature be considered for efficiency...also should mix type of fire class like gas station out door fuel fire and foam ratio per area
Hi Eric.
Water temperature and room temperature have no direct effect on the sprinkler spacing. Sprinkler spacing is a function of the "fire occupancy hazard". If you have a gas station you have a more demanding fire occupancy hazard than an office, so your sprinklers would have to be spaced closer together and you would be required to use a higher water discharge density (gpm/sf).
What is the standard distances if the sprinkler heads upright position under the beam?
There are several factors that can affect that.
The 1st one is Occupancy Hazard. If you are in a Light Hazard space, the maximum spacing is 15' and the maximum protection area allowed is 225sf. If you are in an Ordinary Hazard I, then max spacing is 15', but max area 130sf. There are also obstructions, etc. Check NFPA 13
what in the world happened at 15:15?
I had to make a harsh cut and paste two different videos together, but the point remains valid. Thanks for watching =)