Eric - NFPA 13 is open for public comment, submit your proposal! On Tue, Mar 14, 2023 at 10:09 AM Eric Rieve <[email protected]> wrote:
> As always it comes down to specific situations and judgement. From an ITM > standpoint tie-in drains are incredibly valuable as they significantly > reduce the likelihood of one drain out of many getting missed and causing a > system break. Take a theoretical open warehouse dry system where the riser > and cross main happen to be on the high side of a shed roof, and you have > 20 branch-lines all pitched down to the low eave (don’t laugh, I’ve seen it > before). Tying them all together into a single low-point might cause water > delivery times to skew, but if you instead divided them into four or five > drain clusters then you will have significantly improved the > maintainability of the system while minimizing the “gridding” effect. > > > > The commentary can also be misleading if you only skim the first paragraph > and don’t take time to digest the whole context. The commentary leads with > a comment about how the *drain* should be *at least* 1” in size. This > could easily be misinterpreted as meaning that the tie-in piping should be > at least 1” in size since that is what this code section is about. This > reading would suggest a benefit in increasing the piping to a larger size > which would be in direct conflict with the code section. > > > > It’s not till the very last sentence that the commentary reiterates why 1” > is the max size permitted. The commentary it trying to provide some helpful > context about the hydraulic effects of tie-in drains, but the structure > does make it seem like the author is saying the code section shouldn’t be > followed. > > > > Here is my humble attempt to improve the clarity of the commentary. Based > on my personal opinion of the intent obviously. > > “When two or more adjacent branch lines are trapped in a dry pipe or > preaction system, the ends of the branch lines must be piped together > utilizing > 1” pipe and run to a single low point drain. at least 1 in. (25 mm) in > size, as stated in *16.10.5.3.5* > <https://link.nfpa.org/publications/13/2022/chapters/16#ID000130002180>. > The drain section after the tie-in piping should be sized per the > requirements of 16.10.5.3.5 needs to be equipped with a valve and a > nipple and cap or a valve with a plug to facilitate moisture removal from > the system. > > Properly pitching tie-in drains and removing condensate from drains prior > to freezing weather are extremely important measures. Typically, tie-in > drains consist of smaller-size piping connected to a rather large volume of > piping, and, with these smaller drains, freeze-ups are possible. > > Care should be taken when determining how many branch lines are tied > together to a single drain, Tie-in drains on multiple adjacent branch > lines should be avoided, if possible, because the use of tie-in drains, > in effect, creates a gridded system. Gridded dry pipe systems and gridded > double interlock preaction systems are prohibited by *8.3.2.7* > <https://link.nfpa.org/publications/13/2022/chapters/8#ID000130000804>. > In these types of systems, all the air in the piping must be evacuated > before a steady flow of water is discharged from the operated sprinklers. A > gridded pipe arrangement is likely to result in excessive time delays > before effective sprinkler discharge occurs. Tie-in drains are considered > necessary to allow rapid drainage of systems protecting cold environments. > While The restriction that tie-in drains be limited to 1 in. (25 mm) > should help minimize delays, dividing the branch lines into smaller > groups each with an individual drain manifold may be necessary when a > significant number of adjacent branch lines are present.” > > > > > > Hope this helps! > > Eric Rieve > > Rieve Fire Protection > > > > *From:* [email protected] <[email protected]> > *Sent:* Monday, March 13, 2023 7:53 PM > *To:* 'Discussion list on issues relating to automatic fire sprinklers' < > [email protected]> > *Subject:* [Sprinklerforum] Re: Combining dry system drains > > > > Now that is interesting… > > > > The wording of the code is that tie-in drains are required, but the > commentary says they should be avoided if possible. > > > > The 2022 edition (16.10.5.3.6) has the same wording in both the code and > the commentary. > > > > > > David L. Miller, P.E. > > *Engineered Fire Protection, **LLC* > > 11920 Richcroft Avenue > > Baton Rouge, Louisiana 70814 > > 225-273-5040 > > > > *From:* [email protected] <[email protected]> > *Sent:* Monday, March 13, 2023 6:41 PM > *To:* [email protected] > *Subject:* [Sprinklerforum] Re: Combining dry system drains > > > > 2016 edition NFPA 13 8.16.2.5.3.6 ….. commentary from handbook…..Tie-in > drains on multiple adjacent branch lines should be avoided, if possible, > because the use of tie-in drains, in effect, creates a gridded system > > > > > > *Jeff Normand* > > > > > > *From:* [email protected] <[email protected]> > *Sent:* Monday, March 13, 2023 6:37 PM > *To:* 'Discussion list on issues relating to automatic fire sprinklers' < > [email protected]> > *Subject:* [Sprinklerforum] Re: Combining dry system drains > > > > NFPA 13 (2016 edition) 8.16.2.5.3.6 Tie-in drains shall be provided for > multiple adjacent trapped branch pipes and shall be only 1 in. (25 mm). > Tie-in drain lines shall be pitched a minimum of 1⁄2 in. per 10 ft (4 mm/m). > > > > David L. Miller, P.E. > Engineered Fire Protection, LLC > 11920 Richcroft Avenue > Baton Rouge, Louisiana 70814 > 225-273-5040 > > -----Original Message----- > From: Sean Lockyer <[email protected]> > Sent: Monday, March 13, 2023 6:31 PM > To: [email protected] > Subject: [Sprinklerforum] Combining dry system drains > > Can dry system drains (I.E. - Drum drips) be combined or interconnected ? > > Sean Lockyer > Project Designer > AITLifeSafety > > > > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to > [email protected] > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to > [email protected] > > _________________________________________________________ > SprinklerForum mailing list: > https://lists.firesprinkler.org/list/sprinklerforum.lists.firesprinkler.org > To unsubscribe send an email to > [email protected] -- Kevin Hall, M.Eng., P.E., ET, CWBSP, PMSFPE Sr. Manager, Engineering and Technical Services American Fire Sprinkler Association
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