Because each floor is a separate fire area and not expected to be fully involved at the same time as each adjacent floor. See 2013 NFPA 13, 8.2.1.
The maximum allowable area on any ONE floor for LH or Oh is 52,000 sq. ft. So a single run-in with a single system riser can satisfy the design requirements of your building quite well. Craig L. Prahl Fire Protection Group Lead/SME CH2M 200 Verdae Blvd. Greenville, SC 29607 Direct - 864.920.7540 Fax - 864.920.7129 CH2MHILL Extension 77540 [email protected] From: Sprinklerforum [mailto:[email protected]] On Behalf Of Jeff Bridges Sent: Thursday, September 01, 2016 1:46 PM To: [email protected] Subject: RE: 5 year fire sprinkler Obstruction Assessment - What items in a system define it as a separate wet pipe system? [EXTERNAL] I would respectfully disagree with the below analogy. Example: (4) Story building consisting of 30K SF per floor Single lead-in supply- combo standpipe with floor controls. How can it be considered a single system when it exceeds the allowable floor space per riser? Just sayin’ Jeff Bridges JBFP Inc I have to disagree with this analysis that a floor control valve defines a system. A floor control valve is not even defined individually in 2013 whereas a sprinkler system is (no mention of floor control valves) as are control valves. As always, I would consider a system to be what it has always been and the addition of the required floor control valve and associated requirements on systems in multi-story buildings just nationally codifies a common practice hereabouts of building a system that has isolatable floors. This way an entire large building does not need to be drained to make a repair or for a T.I., leaves fore protection in service on floors not effected and also conserves water. I'm open to an argument that changes my mind but this one doesn't.
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