You seem to be stating that the pendant sprinklers at the lower ceiling are spaced to cover the entire floor area; the sprinklers in the ceiling pockets are essentially in place ONLY because the pocket doesn't meet any of the criteria in NFPA 13 for omitting sprinklers within. Their coverage of the floor below over-laps the coverage from the pendants.
Under that scenario, I would argue that the sprinklers in the lower ceiling should adequately protect the hazard. The sidewalls in the ceiling pockets with reduce any delay in sprinkler operation due to the pockets and essentially provide "extra water" to the floor area below. If your calculations can support full flow of the design area, plus the sprinklers in the ceiling pockets, it seems that you should be fine. But this will require buy-in from the AHJ. The sidewall sprinklers are still not listed for Extra Hazard. This could result in a ruling against using the sidewalls for the sole reason that "the standard says so" - and so it may not matter if the arrangement will work. Mark A. Sornsin, PE Fire Protection Engineer Ulteig Engineers, Inc. Fargo, ND 701.280.8591 [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Thursday, April 17, 2008 8:09 AM To: [email protected] Subject: Extra Hazard Ceiling Pockets Forum, Let me know what you guys think about this situation. I have a college lab building where the AHJ bumped us up to Extra Hazard Occupancy in the Basement due to storage of flamabile liquids. The labs in the basement have a 3 foot deep ceiling pocket above the experiment table in the center of the room. We spaced pendents at extra hazard spacing throughout the room at the lower ceiling level. We then added two sidewall sprinklers in the ceiling pocket itself. The question as arisen whether we can use sidewalls because the room is to be designed at extra hazard. My therory was that the floor level is protected to extra hazard from the pendents and the sidewalls are only protecting the ceiling pock itself and not the room below. Does anyone agree/disagree with my reasoning. This email is intended for named recipients only. _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field) _______________________________________________ Sprinklerforum mailing list [email protected] http://lists.firesprinkler.org/mailman/listinfo/sprinklerforum To Unsubscribe, send an email to:[EMAIL PROTECTED] (Put the word unsubscribe in the subject field)
