Roland, thank you for posting on this. I was intending to calculate the in-racks regardless of the reason for their installation, but the current language can lead to creative reading.
Regarding substituting Group A for Class IV, I'm hesitant to use this approach for encapsulated Class IV since encapsulation appears to boost the protection up a notch. Maybe because encapsulated in-racks are 8 ft spacing and plastics in-racks are 4-5 ft spacing for a similar one-level in-rack configuration (each having 8 head flow @ 15 psi)? I see 16.1.2.2 and the associated Annex material but I wish the word "encapsulated" would have appeared in these sections. Bill Brooks William N. Brooks, P.E. Brooks Fire Protection Engineering Inc. 372 Wilett Drive Severna Park, MD 21146-1904 410-544-3620 410-544-3032 FAX 412-400-6528 Cell -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Roland Huggins Sent: Thursday, February 17, 2011 2:52 PM To: [email protected] Subject: Re: Rack Storage Sanity Check (13-2010) I disagree with your assumption that you only add the in-rack demand when the arrangement without excessive clearance would otherwise call for in-rack sprinklers. The supplemental in-racks are offsetting the clearance operating simultaneously with the ceiling sprinkler. Having said that 12.1.3.4 is SLIENT on this issue. Call that an OOPS. I will pursue it at the ROC stage. As for Class IV exceeding Group A plastic, it happens. The Class IV criteria is judgement driven with minimal testing behind it so a strong dose of conservatism was warranted. Group A plastics have had a ton of tests and when the same storage arrangement for Group A has a lower demand than Class IV, you can apply the Group A criteria (see 16.1.2.2) Roland On Feb 17, 2011, at 7:13 AM, Bill Brooks wrote: > Me too until the 2010 language. Now it appears a single row of in- > racks can > be used to make up for the excess ceiling clearance requirements for > Chapters 16 and 17. With this set of in-racks in place the racks > can be > calculated at the actual storage height rather than the theoretical > Ceiling > - 20 Chapter 16 (or Ceiling - 10 Chapter 17) height required by > 13-2007. > > The way I read this is the "ceiling clearance in-rack" flow does not > have to > be added to ceiling flow if the commodity class and "assumed > acceptable > clearance" would not otherwise require in-racks. When the actual > storage > height would necessitate the in-racks, then the in-racks could serve > double > duty as the required in-racks as well as the "ceiling clearance in- > racks". > In this case the in-rack flow is added. > > All this being stated, my concern is whether this approach is OK for > the > Chapter 17 plastics. > > Bill Brooks _______________________________________________ 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) _______________________________________________ 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)
