Don't confuse automatic and manual water supplies. The intent of this section is that if you are going to use an existing standpipe to supply new sprinklers, by turning it into a combined system, then it must be a minimum of 4" diameter. It must be capable of delivering the sprinkler demand as calculated, and also the Class 1 demand via the FDC (we're presuming this isn't a high-rise, correct?). And if it's a Class III it is already presumably designed to supply the Class II demand, though if the building is to be fully sprinklered via the scope of the retrofit project then I'd say you can take the exception and go with the reducers.
That said, the second part of the question confuses me. The "water supply" is delivered by the responding FD if it's a manual system; what other water supply upgrades are you considering or referring to? The foregoing is my opinion only and does not necessarily represent the opinion or intent of the NFPA 14 Technical Committee on Standpipe and Hose Systems. Steve Leyton Protection Design & Consulting San Diego, CA -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Todd Williams Sent: Thursday, March 11, 2010 2:12 PM To: [email protected] Subject: Class I vs Class III standpipe Something I have been confused on for a while and I thought I would put out there. Here is a section of NFPA 14 section 5.4.1, Class I Standpipes: 5.4.1.3 Where an existing standpipe system having standpipes with a minimum diameter of 4 in. (100 mm) is to be utilized to supply a new retrofit sprinkler system, the water supply required by Section <http://codesonline.nfpa.org/a/c.ref/2010_ID02001400917/sec>7.10 shall not be required to be provided by automatic or semiautomatic means, provided that the water supply is adequate to supply the hydraulic demand of the sprinkler system in accordance with <http://codesonline.nfpa.org/a/c.ref/NFC13/book>NFPA 13, Standard for the Installation of Sprinkler Systems. So if the existing 4" standpipe does not have an adequate water supply, you can either increase the water supply or sprinkler the building to make it meet the standard, correct? Sort of makes sense. However, this applies only to Class I systems and not Class III. Many times the only difference I see between Class I and Class III is a 2-1/2 x 1-1/2 reducer. So if you have the reducer on you need to provide 100 psi at the top outlet, but if you take the reducer off you don't have to? To me this doesn't make a lot of sense. Also, if the standpipe and sprinklers are installed at the same time, you need to meet the 100 psi at the top outlet for the standpipe. True? If you have a 3 story apartment building with an NFPA 13R system, do you have to meet the 100 psi as well? (This is the real world example I have right now) Todd G. Williams, PE Fire Protection Design/Consulting Stonington, Connecticut 860-535-2080 www.fpdc.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field) __________ Information from ESET NOD32 Antivirus, version of virus signature database 4937 (20100311) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com __________ Information from ESET NOD32 Antivirus, version of virus signature database 4937 (20100311) __________ The message was checked by ESET NOD32 Antivirus. http://www.eset.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum For Technical Assistance, send an email to: [email protected] To Unsubscribe, send an email to:[email protected] (Put the word unsubscribe in the subject field)
