I do love a good can of worms! I fully expected differing opinions on this. Ultimately, it comes down to how much delay there will be getting water to any given open sprinkler and how much delay is deemed acceptable. If system volume is less than 750 gpm (yes, a QOD is required) and it's not protecting a dwelling unit, then there is no maximum water deliver time. So the 'no gridded dry systems' was added in the 1991 edition (as best I can tell) because gridded dry systems (the text-book type grids, not the want-a-be in my original post) exhibited excessive water deliver delays. The commentary in the older editions is a bit more robust then the 2019. Hybrid systems are a grey area.
Thanks to everyone for contributing. Good conversation! Ed K -----Original Message----- From: Sprinklerforum <[email protected]> On Behalf Of Skyler Bilbo via Sprinklerforum Sent: Wednesday, October 27, 2021 12:48 PM To: [email protected] Cc: Skyler Bilbo <[email protected]> Subject: Re: Gridded dry system IMHO, defining a grid as any system that can supply a sprinkler from more than one direction is a poor threshold. Just because you install sprinklers on a looped main or line, does not magically turn it into a gridded system. The location of the sprinklers should have nothing to do with it. May I suggest the following definition of gridded piping: "piping installed such that any loop in the system has more than one connection capable of providing water to the loop from the same supply; a loopty loop." Maybe leave the last part out. Up to you. -Skyler On Wed, Oct 27, 2021, 12:17 PM Chad Mitchell via Sprinklerforum < [email protected]> wrote: > Here is an Informal Interpretation of a similar layout from November > 13, 2009. > > https://www.dropbox.com/sh/8e4v0xvfri07c5i/AADbhtdz25iS_1Qkdbnh1lWqa?d > l=0 > > Regards, > > Chad Mitchell > Mid Atlantic Fire Protection, Inc. > > -----Original Message----- > From: Sprinklerforum <[email protected]> > On Behalf Of J H via Sprinklerforum > Sent: Wednesday, October 27, 2021 1:03 PM > Cc: J H <[email protected]>; > [email protected] > Subject: Re: Gridded dry system > > So, on any looped system, if you add sprinklers to the looped main > (adding flow from more than two directions) does that now constitute a > grid? I see both viewpoints but am posing as devil's advocate. As I > said I would steer clear from the original scenario unless necessity dictated otherwise. > > JH > > On Wed, Oct 27, 2021 at 9:58 AM J H <[email protected]> wrote: > > > I would call it a Tree/Loop hybrid. :-P > > > > The branchlines are not connecting two parallel cross mains per the > > definition of a grid. > > JH > > > > > > On Wed, Oct 27, 2021 at 9:50 AM Kevin Hall <[email protected]> > > wrote: > > > >> If the pipe marked in red is removed and capped off, it eliminates > >> any split flows/transfer lines on the branch lines. So with the red > >> pipe removed I would define it as a tree. With the red pipe > >> installed, I would define it as a grid. > >> > >> The above is my opinion and has not been processed as a formal > >> interpretation in accordance with the NFPA Regulations Governing > >> Committee Projects. This is provided with the understanding that > >> the AFSA assumes no liability for this opinion or actions taken on > >> it and they are not to be considered the official position of the > >> NFPA or its > technical committees. > >> AFSA cannot provide design or consulting engineering services, and > >> this opinion should therefore not be considered, nor relied upon, > >> as > such. > >> > >> > >> Kevin Hall, M.Eng., P.E., ET, CWBSP, PMSFPE > >> > >> Coordinator, Engineering and Technical Services > >> > >> American Fire Sprinkler Association > >> > >> [email protected] > >> > >> 214-349-5971 > >> > >> > >> On Wed, Oct 27, 2021 at 12:47 PM J H via Sprinklerforum < > >> [email protected]> wrote: > >> > >>> So, for discussions sake take a look at the image link - what > >>> would you all call this system? I have my opinion but I don't see > >>> how it's much different than Ed's original drawing: > >>> https://ibb.co/xSW04dj > >>> > >>> On Wed, Oct 27, 2021 at 9:46 AM J H <[email protected]> > wrote: > >>> > >>> > So, for discussions sake take a look at the image link - what > >>> > would you all call this system? I have my opinion but I don't > >>> > see how it's much different than Ed's original drawing: > >>> > https://ibb.co/xSW04dj > >>> > > >>> > On Wed, Oct 27, 2021 at 9:40 AM Kevin Hall > >>> > <[email protected]> > >>> > wrote: > >>> > > >>> >> Yes, I see that now... looks like I have another PI to add to > >>> >> the > >>> NFPA 13 > >>> >> list. Look for that line of sprinklers to be removed in the > >>> >> 2025 > >>> edition > >>> >> haha. > >>> >> > >>> >> The above is my opinion and has not been processed as a formal > >>> >> interpretation in accordance with the NFPA Regulations > >>> >> Governing > >>> Committee > >>> >> Projects. This is provided with the understanding that the AFSA > >>> assumes no > >>> >> liability for this opinion or actions taken on it and they are > >>> >> not to > >>> be > >>> >> considered the official position of the NFPA or its technical > >>> committees. > >>> >> AFSA cannot provide design or consulting engineering services, > >>> >> and > >>> this > >>> >> opinion should therefore not be considered, nor relied upon, as > such. > >>> >> > >>> >> > >>> >> Kevin Hall, M.Eng., P.E., ET, CWBSP, PMSFPE > >>> >> > >>> >> Coordinator, Engineering and Technical Services > >>> >> > >>> >> American Fire Sprinkler Association > >>> >> > >>> >> [email protected] > >>> >> > >>> >> 214-349-5971 > >>> >> > >>> >> > >>> >> On Wed, Oct 27, 2021 at 12:19 PM J H via Sprinklerforum < > >>> >> [email protected]> wrote: > >>> >> > >>> >>> Kevin, > >>> >>> That's true for most of the sprinklers in the diagram but look > >>> >>> at > >>> figure > >>> >>> A.3.3.206.6 (2019) - the farthest loop from the supply has > >>> sprinklers on > >>> >>> it > >>> >>> and it's connecting both loops - those sprinklers are > >>> >>> receiving water from two mains. Likewise, per the definition > >>> >>> of a main the only main in > >>> Ed's > >>> >>> example is the center line. Everything else are looped > >>> >>> branchlines > >>> per > >>> >>> the > >>> >>> definitions. > >>> >>> > >>> >>> JH > >>> >>> > >>> >>> > >>> >>> On Wed, Oct 27, 2021 at 9:09 AM Kevin Hall via Sprinklerforum > >>> >>> < [email protected]> wrote: > >>> >>> > >>> >>> > The annex shows the branch lines fed by the cross main from > >>> >>> > two > >>> >>> directions, > >>> >>> > the sprinkler can still only receive water from one > >>> >>> > direction from > >>> the > >>> >>> > branch line... that is the distinction in the definition. > >>> >>> > > >>> >>> > The above is my opinion and has not been processed as a > >>> >>> > formal interpretation in accordance with the NFPA > >>> >>> > Regulations Governing > >>> >>> Committee > >>> >>> > Projects. This is provided with the understanding that the > >>> >>> > AFSA > >>> >>> assumes no > >>> >>> > liability for this opinion or actions taken on it and they > >>> >>> > are not > >>> to > >>> >>> be > >>> >>> > considered the official position of the NFPA or its > >>> >>> > technical > >>> >>> committees. > >>> >>> > AFSA cannot provide design or consulting engineering > >>> >>> > services, and > >>> this > >>> >>> > opinion should therefore not be considered, nor relied upon, > >>> >>> > as > >>> such. > >>> >>> > > >>> >>> > > >>> >>> > Kevin Hall, M.Eng., P.E., ET, CWBSP, PMSFPE > >>> >>> > > >>> >>> > Coordinator, Engineering and Technical Services > >>> >>> > > >>> >>> > American Fire Sprinkler Association > >>> >>> > > >>> >>> > [email protected] > >>> >>> > > >>> >>> > 214-349-5971 > >>> >>> > > >>> >>> > > >>> >>> > On Wed, Oct 27, 2021 at 12:05 PM J H via Sprinklerforum < > >>> >>> > [email protected]> wrote: > >>> >>> > > >>> >>> > > I have a problem with the simplified definition floated > >>> >>> > > out here > >>> >>> that a > >>> >>> > > grid system is one that feeds a sprinkler from two > >>> >>> > > directions > >>> >>> because of > >>> >>> > > the illustration of a looped system in the annex of '13 > >>> >>> > > which > >>> shows > >>> >>> > > sprinklers attached to the end portion of the loop > >>> >>> > > resulting in > >>> those > >>> >>> > > sprinklers receiving water from two directions. > >>> >>> > > Technically the > >>> only > >>> >>> > cross > >>> >>> > > main is the center piping - everything else are looped > >>> branchlines. I > >>> >>> > would > >>> >>> > > be prepared for kickback from a knowledgeable AHJ. I would > >>> personally > >>> >>> > avoid > >>> >>> > > a design like this if at all possible to avoid the > >>> >>> > > headache of > >>> >>> hashing it > >>> >>> > > out w/ an AHJ. But if it's the difference between a system > >>> >>> > > like > >>> this > >>> >>> and > >>> >>> > a > >>> >>> > > fire pump it might be worth the fight. > >>> >>> > > > >>> >>> > > JH > >>> >>> > > > >>> >>> > > On Wed, Oct 27, 2021 at 6:04 AM Sean Conlin via > >>> >>> > > Sprinklerforum < [email protected]> > wrote: > >>> >>> > > > >>> >>> > > > If you were to put caps on the left and right lines > >>> >>> > > > going > >>> north and > >>> >>> > > south, > >>> >>> > > > it resembles a compound gridded system and a sprinkler > >>> >>> > > > can > >>> receive > >>> >>> > water > >>> >>> > > > from both sides. > >>> >>> > > > > >>> >>> > > > The east and west lines are essentially the mains and so > >>> >>> > > > is > >>> the 4" > >>> >>> in > >>> >>> > the > >>> >>> > > > middle. > >>> >>> > > > > >>> >>> > > > Yes is has a looped piping arrangement and is > >>> >>> > > > symmetrical but > >>> it > >>> >>> is a > >>> >>> > > > gridded system by NFPA-13 definition. If you were to > >>> >>> > > > not tie > >>> the > >>> >>> lines > >>> >>> > > > together, it would be a loop. > >>> >>> > > > > >>> >>> > > > Regards, > >>> >>> > > > > >>> >>> > > > Sean W. Conlin > >>> >>> > > > E:[email protected] > >>> >>> > > > > >>> >>> > > > This message, including any attachments is considered > >>> confidential > >>> >>> and > >>> >>> > > for > >>> >>> > > > use only by the intended recipient(s). > >>> >>> > > > Any other distribution, copying or disclosure is > >>> >>> > > > strictly > >>> >>> prohibited. > >>> >>> > > > Please delete this communication and notify Demand > >>> >>> > > > Sprinkler Design Inc. if you are not the intended > >>> recipient > >>> >>> or > >>> >>> > > have > >>> >>> > > > received this message in error. Demand Sprinkler Design > >>> >>> > > > Inc. accepts no responsibility or liability > >>> for > >>> >>> any > >>> >>> > loss > >>> >>> > > > or damage from use, including damage from viruses. > >>> >>> > > > > >>> >>> > > > -----Original Message----- > >>> >>> > > > From: Ed Kramer <[email protected]> > >>> >>> > > > Sent: October 26, 2021 1:31 PM > >>> >>> > > > To: [email protected] > >>> >>> > > > Subject: Gridded dry system > >>> >>> > > > > >>> >>> > > > Is this sprinkler system a gridded system? I've avoided > this > >>> >>> type of > >>> >>> > > > design in the past for dry systems because it 'kinda' a > >>> >>> > > > grid, > >>> but > >>> >>> not > >>> >>> > > > really. Now I'm questioning my questioning. What are > >>> >>> > > > your > >>> >>> thoughts? > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > Reference NFPA 13 (2019) sections 8.2.3.10 and 3.3.206.5. > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > >>> >>> > >>> https://www.dropbox.com/s/u2hw3cbvlga4fcq/Dry%20Attic%20System.pdf > >>> ?d > >>> l=0 > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > Ed Kramer > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > _______________________________________________ > >>> >>> > > > Sprinklerforum mailing list > >>> >>> > > > [email protected] > >>> >>> > > > > >>> >>> > > > > >>> >>> > > > >>> >>> > > >>> >>> > >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firespr > >>> in > >>> kler.org > >>> >>> > > > > >>> >>> > > _______________________________________________ > >>> >>> > > Sprinklerforum mailing list > >>> >>> > > [email protected] > >>> >>> > > > >>> >>> > > > >>> >>> > > >>> >>> > >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firespr > >>> in > >>> kler.org > >>> >>> > > > >>> >>> > _______________________________________________ > >>> >>> > Sprinklerforum mailing list > >>> >>> > [email protected] > >>> >>> > > >>> >>> > > >>> >>> > >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firespr > >>> in > >>> kler.org > >>> >>> > > >>> >>> _______________________________________________ > >>> >>> Sprinklerforum mailing list > >>> >>> [email protected] > >>> >>> > >>> >>> > >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firespr > >>> in > >>> kler.org > >>> >>> > >>> >> > >>> _______________________________________________ > >>> Sprinklerforum mailing list > >>> [email protected] > >>> > >>> http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firespr > >>> in > >>> kler.org > >>> > >> > _______________________________________________ > Sprinklerforum mailing list > [email protected] > > http://lists.firesprinkler.org/listinfo.cgi/sprinklerforum-firesprinkl > er.org This email and any files transmitted with it are confidential > and intended solely for the use of the individual or entity to whom > they are addressed. > If you have received this email in error please notify the system manager. > This message contains confidential information and is intended only > for the individual named. 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