I would have maintained the hydraulic area within the room and added additional heads on the next branch line as described in A.22.4.4.1, not gone to an adjacent, separate room. There are several sprinklers flowing less than their required flow based on their coverage area so there are other issues with the layout and design. Overall the total gpm flow in the calc appears to be within the expected flow rate based on rough numbers of a .40 over 3000 requiring at least 1200 gpm. The calc shows a flow rate of approximately 1300 gpm.
However I cannot readily accept sprinklers 2-5 ft from the system main being more hydraulically remote than those which are 40-50 ft from the main. Based on the layout there are only 6 heads on the branchlines within the room, based on 1.4*sq rt of 3000 / 9 ft spacing (underwriter requires 1.4 factor be applied) you should calc 8 heads per branchline so they just included the next two heads on the other side of the wall and system main. Craig L. Prahl, CET Fire Protection CH2MHILL Lockwood Greene 1500 International Drive Spartanburg, SC 29304-0491 Direct - 864.599.4102 Fax - 864.599.8439 CH2MHILL Extension 74102 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Roland Huggins Sent: Tuesday, April 03, 2012 12:35 PM To: [email protected] Subject: Re: mixing densities in same calculated area bottom line is you are required to drop a rectangle over the area that creates the greatest hydraulic demand. Excluding a 0.4 density area to include a 0.17 area (with smaller K-factors) can be safely assumed to present less of a demand. Show me the numbers if you want to do something that appears wrong to prove it is acceptable. If the area of the higher density is smaller than the minimum size, then you pick up sprinklers from an adjacent area with a lower density. The TC has gone to great pains to address this in A.11.1.2 (as well as in 12.1). Even expanded it this cycle to address areas smaller than the size for the higher hazard but larger than the surrounding classification (ie a 1600 sf EH in an OH building which the current text would imply to do a 1500 sf remote area). As someone already said, seems this is a closed case of just not following the procedure of ch 22.4.4.1 (or lack of understanding what is meant by HYDRAULICALLY most demanding). Roland On Apr 3, 2012, at 8:50 AM, <[email protected]> <[email protected]> wrote: > > Got a submittal package where the contractor has two divided rooms. > One is 0.40/3000 and adjacent room is .17/2000. He is calculating > the .40 area and has extended his hyd remote area beyond the wall of > the room into the adjacent .17 area and calced about 8 heads. > The .40 room is plenty large enough to allow the additional > sprinklers to be calced from within the room. > > Off the top of your head does anyone know where this type of thing > is addressed within NFPA 13? > > Craig L. Prahl, CET -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://fireball.firesprinkler.org/mailman/private/sprinklerforum/attachments/20120403/f3c37377/attachment.html> _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
