Increasing the pipe sizes upstream of the remote sprinkler can cause a situation called "over spray" or "excess discharge". This increased discharge increases the total water demand on the supply which in turn lowers the available pressure which will decrease the safety margin. Just from my experiences.
Russell Rewis Brown Automatic Sprinklers, Inc. 107C Hemlock Street Valdosta, Georgia 31601 229-244-8130 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, May 12, 2010 8:28 AM To: [email protected] Subject: RE: Pipe Size Charles , The AHJ can require new calculations if you are reducing pipe size . In your case you are increasing the end piece which always tends to balance the head flows more efficiently.This should actually make the system better.JMHO BTW , make sure you are using the same type of pipe. ---- John Drucker <[email protected]> wrote: > 2002 NFPA-13 > > 14.1.2 Deviation from approved plans shall require permission of the > authority having jurisdiction. > > 14.4.4.5 Friction Loss. Pipe friction loss shall be calculated in accordance > with the Hazen-Williams formula with C values from Table 14.4.4.5, as > follows: > (1) Include pipe, fittings, and devices such as valves, meters, flow > switches in pipes 2 in. or less in size, and strainers, and calculate > elevation changes that affect the sprinkler discharge. > > John Drucker, CET > Fire Protection Subcode Official > Fire/Building/Electrical Inspector > Fire Marshals Office > Borough of Red Bank, NJ > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Tuesday, May 11, 2010 5:09 PM > To: [email protected]; [email protected] > Subject: RE: Pipe Size > > If you change pipe sizes, then yes you'd have to recalc. That's pretty much > a given since your system hydraulics can change and you'll have no idea of > the overall affect on the system performance. > > Craig L. Prahl, CET > Fire Protection Specialist > Mechanical Department > CH2MHILL > Lockwood Greene > 1500 International Drive > Spartanburg, SC 29304-0491 > Direct - 864.599.4102 > Fax - 864.599.8439 > [email protected] > http://www.ch2m.com > > > -----Original Message----- > From: [email protected] > [mailto:[email protected]] On Behalf Of Charles > Thurston > Sent: Tuesday, May 11, 2010 4:32 PM > To: sprinklerforum > Subject: Pipe Size > > Hello All you Fine folks of the Sprinklerforum, > > I am looking at replacing all the pipe in a 2 story parking deck due to > external corrosion (The fitters will love to be to look at the beach while > they "work"). 3" main fed from a 500 GMP ??PSI pump. The building the pump > feeds is 16 stories of condos. > > > Each branch line feeds 5 heads now. > 1 1/4" from main feeds heads 1-4 and 1" to the 5th head. It will be cheaper > to run the branch line all the way out in 1 1/4 fitting and machine > adjustment wise. The AHJ "ask" if it was allowable to change the pipe size > without re-calcing the entire system. It is planned to measure out the pipe > lengths and out the heads back in the same locations. I have not found > anything in NFPA 13 2007 addressing this. Does anybody know a reason not to > run 1 1/4" all the way out other than to "balance the flow" in the last > head. > > -- > Best regards, > Charles Thurston mailto:[email protected] > Coastal Fire Protection/ Myrtle Beach Fire & Safety Group. > AFAA Guest > > Electronic Privacy Notice: > This e-mail, and any attachments, contains information that is, or may > be, covered by electronic communications privacy laws, and is also > confidential and proprietary in nature. If you are not the intended > recipient, please be advised that you are legally prohibited from > retaining, using, copying, distributing, or otherwise disclosing this > information in any manner. 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