How should I properly be sizing a vertical branch line that feeds only a five-story trash chute?
Would a hydraulic calculation be a line calculation, so I would calculate as many as five sprinklers?
I typically feed sprinklers from the adjacent floor level, so I've never ran a separate calculation just for a trash chute. My gut says a 1-inch threaded line isn't enough for a trash chute, but I'm not 100% positive how a hydraulic calculation should be done here.
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10/13/2021 07:26:10 am
10/13/2021 08:17:55 am
Are you not able to run a 1" line to the trash chute off the lines on each floor? I think that would be more cost effective then running a new line up the entire chute.
10/13/2021 11:59:52 am
I depends on the AHJ-preferred configuration.
10/13/2021 08:20:15 am
2021 IBC 903.2.11.2 Rubbish and linen chutes requires sprinkler heads at the top of the chute, in the termination room, and at alternate floors (begining w/the second level below the last intake and ending with the floor above the discharge) and at the lowest intake.
10/13/2021 08:22:24 am
Trash and linen chutes are covered in NFPA 13 22.15. Usually a sprinkler every other floor is needed. There is no specific requirement to calc the chute as the sprinkler head is usually fed of each floors system. I don't think I have ever seen an independent system just for a trash chute.
10/13/2021 08:22:35 am
I have never been required to submit a separate calculation for the trash chute.
10/13/2021 08:34:13 am
I have sized a trash chute riser in a 42-story high rise to be 2" pipe (although this building had fire pumps & PRVs). We used a hydraulic calculation as outlined in NFPA 13 (2016): 188.8.131.52.1, which requires only three sprinklers to be calculated (at a minimum of 15 GPM).
10/13/2021 08:57:16 am
I don't think I have ever calc'd a chute. Chapter 22 in NFPA deals with trash / linen chutes along the auspices of sprinkler placement and such, but typically those sprinklers are fed from floor level systems. I think I'd want to avoid a separate system if I could.
Yes, calc 3 heads.
10/13/2021 01:28:22 pm
I have been placing heads in trash chutes sincince I can nopt remember when. Although NFPA 13 only requires every other floor , Trash chutes are generally manufactured now with a factory installed sprinkler head at the door to the chute. Genrally I have placed an 1 1/4" control assembly and risert to feed this type of assembly at every floor. I have never been asked to calculate it. Lets face it most heads are high rises with 100 plus psi avalable at the highest floor. A single head would discharge 56 gpm. So reasoning rules. Whatever you do don't let this out as it will start a reaction and then the "what if" reviewers will take over. I can remeber years a go (early 1990's) when a Fire Marshall was inspecting a job I was doing and a duct passes through the corener of a closet that was 6 ' by 2'. The bulkheads lowered the cieling in the oine end of the closets by 12" and was about 18" wide. Rather than argue with him I said I'll tell you what, I'll give you a torch and stand you in the corner under the bulkhead and I'll set the head off. Let me know if you get wet.." That was it he pulled off the idea of requitring a second head. Why because common sense prevailed. There are those however where therre is no common sense. So leave dead dogs lie. Technicall y as pointed out it is 3 heads, but then you cna go everyother floor. Pick your poision.
10/13/2021 01:32:12 pm
I agree David, I will also add that you are costing your customer to do things that are not necessary or needed. running a separate line just for the heads in the chute on a 5 story building is a waste of money and time for your fitters that are probably going to cuss you out for running it.
10/14/2021 12:27:18 pm
Yes but here AHJ's generally require a control valve and flow swtich at every floor. So cost are not necessarialy appples to aples and added cost of addtional Fire Alarm Monitor Modules general out weigh the single feed riser system.
10/23/2021 10:00:19 am
I 100% agree that doing things above and beyond code is not a path to go down often. In this case, there is a potential "what if" situation that may be more probable than some that are often proposed. More often than not this points me to a separate line design. With a separate line and one control valve at the base of the chute water flow can be shut down in a case of accidental discharge of a sprinkler due to physical damage. I know there is protection designed into these chutes and they do there job for the most part. With feeds off each floor, if someone at the bottom of the chute encounters water, they need to close feeds at ever floor until they find the correct floor. By then there could be significant water damage.
10/14/2021 11:34:23 am
184.108.40.206 Special Design Areas.
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