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)
