Does NFPA 13 address the ability to size sprinkler pipe simply by being "sized by similarity"?
For instance, I have a small room that has (4) 1/2" pendent sprinklers to be located in it. I cannot determine any pipe routing from above due to an old ceiling but can verify the lines are 1-1/2" schedule 40. I've heard of this method being used but do not find it in NFPA 13 so I'm hesitant to use this method. Thanks in advance. Sent in anonymously for discussion. Click Title to View | Submit Your Question | Subscribe
7 Comments
Dan Wilder
12/15/2023 07:58:22 am
Are you trying to not provide calculations for a project? Typically, when we provide TI services, the existing piping schedule, piping method, and sprinkler K-Factor gets followed or we provide calc's to prove something new (like adding flex hoses vs hard pipe).
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Glenn Berger
12/15/2023 08:12:36 am
In small applications, the replace in kind method tends to be acceptable as long as the contents/room being protected is "Light Hazard."
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Jesse
12/15/2023 08:50:14 am
I feel ya. Seems this is Light Hazard and I'm guessing by the age and Sch 40 pipe, this may be a Light Hazard Pipe Schedule. In that event, yep.
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Casey Milhorn
12/15/2023 08:56:45 am
There are millions of different scenarios that NFPA 13 just cannot cover, especially when it comes to remodels, upfits, etc... Not that 13 does a bad job, it just isn't practical for it to cover everything. Many AHJs have their own rules on this. One of my favorites is not needing drawings for 10 heads or less being relocated, and not needed calculations for 10 or less new sprinklers (when matching existing pipe schedule). Of course even this can be abused, but it's a good starting point. But to answer your question, it's going to be AHJ specific. I've found most AHJs just want some type of common sense reasoning on why you are doing what you are doing, and if they trust you and know you are ethical and knowledgeable, they will typically show a lot of grace.
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Alex
12/15/2023 09:29:55 am
If the system is designed as pipe schedule, I can see it working but if its a hydraulically calculated deign, I don't see how you can justify simply matching pipe sizes since you will be adding fittings and additional sections of pipe.
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Jack G
12/15/2023 12:02:41 pm
When we calculate a system it is “the hydraulically most remote area “.
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sean
12/31/2023 06:01:48 pm
I am a reviewer so i take these factors into account.
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