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, SCĀ  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

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