With due respect I don't agree they have to stay in the room. If it's area density method I don't see where is says you can make them stay in the room if the length on the BL carries them out. Is it good design? I don't know that's not the question. But it's Code complaint.
Without an EOR establishing anything other than NFPA 13 we are stuck. It clearly says you don't have to calc 15' beyond when there is a partition "capable of preventing heat from a fire in one area from fusing sprinklers in the adjacent area". Note it doesn't say rated. I suppose to some capable could mean rated. Next is the annex section clarifying the restrictions on changing orifices. "The use of sprinklers with differing orifice sizes in situations where different protection areas are needed is not considered balancing." When I was in contracting we ran into this often in grocery stores back room. The wall wasn't usually rated. When the BL ran parallel to the long back room it was a higher demand than when they ran perpendicular and crossed into the sales space. Back room say a 16' class IV and the sales floor OHII. In these case the orientation of the steel drove the design. One more thought, usually adding heads to the BL is the most demanding situation pressure wise. Is anyone sure staying in the room is always more demanding. Guess it depends how many 5.6 heads are picked up along the BL. Sure the flow would be greater staying in the room but it may be at less a pressure because you are taking less of a hit on the BL which is usually where the pressure hurts the most being smaller pipe. Where are the two points on the curve. If it's a simple enough design I'd calc it myself before sending it back. I'd sure want to know the answer before I had the fight. 12.3* Adjacent Hazards or Design Methods. For buildings with two or more adjacent hazards or design methods, the following shall apply: (1) Where areas are not physically separated by a barrier or partition capable of delaying heat from a fire in one area from fusing sprinklers in the adjacent area, the required sprinkler protection for the more demanding design basis shall extend 15 ft (4.6 m) beyond its perimeter. (2) The requirements of 12.3(1) shall not apply where the areas are separated by a barrier partition that is capable of preventing heat from a fire in one area from fusing sprinklers in the adjacent area. Annex kinda gets into this. Although not exactly I'll admit. A.12.3 The situation frequently arises where a small area of a higher hazard is surrounded by a lesser hazard. ... If the storage is separated from the surrounding area by a floor-to-ceiling/roof partition that is capable of preventing heat from a fire on one side from fusing sprinklers on the other side, the size of the operating area is determined by the occupancy of the surrounding area. In this example, the design area is 1500 ft2 (139 m2). A 0.3 gpm/ft2 (12.2 mm/min)density is needed within the separated area with 0.2 gpm/ft2(8.1 mm/min) in the remainder of the remote area. I think you are thinking of the restriction: 22.4.4.8.2 Unless the requirements of 22.4.4.8.3 or 22.4.4.8.4 are met, mixing of sprinklers of different orifice sizes by reducing the orifice size of adjacent sprinklers on the same branchline leading back to the main for the purpose of minimizing sprinkler over discharge shall not be permitted. 22.4.4.8.3 Sprinklers with different orifice sizes shall be acceptable for special use such as exposure protection, small rooms or enclosures, or directional discharge. (See 3.3.17 fordefinition of small rooms.) A.22.4.4.8 The use of sprinklers with differing orifice sizes in situations where different protection areas are needed is not considered balancing. An example would be a room that could be protected with sprinklers having different orifice size in closet, foyer, and room areas. However, this procedure introduces difficulties when restoring a system to service after operation since it is not always clear which sprinklers go where. Chris Cahill, PE* Senior Fire Protection Engineer, Aviation & Facilities Group Burns & McDonnell 8201 Norman Center Drive Bloomington, MN 55437 Phone: 952.656.3652 Fax: 952.229.2923 [email protected] www.burnsmcd.com Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered in: MN -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Todd Williams Sent: Tuesday, April 03, 2012 11:01 AM To: [email protected] Subject: RE: mixing densities in same calculated area The calcs need to be redone to include a 3000 sqft remote area in the 0.40 space. Hydraulically more remote. Is it a rated wall between the 0.17 and 0.40? K factors can be mixed (think regular heads and XCOV sidewalls). Also, read A11.2.3.2.1.1 (2002) At 11:50 AM 4/3/2012, you wrote: >But I don't have a 3000 sf design area for the 0.40 density area. This is >palletized storage of group A plastic and Class IV commodities. Total square >footage for the room is almost 5,000 sq. ft. > >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 Cahill, >Christopher >Sent: Tuesday, April 03, 2012 11:44 AM >To: [email protected] >Subject: RE: mixing densities in same calculated area > >Sounds like the difference between the room design method and the area density >method. Stay within the room regardless of shape of RA or minimum length >along the BL? I don't think the standard tells us which to use. If they >crossed the wall sounds like area density and there are very specific rules on >the shape of the area. And if the walls aren't rated the only choice the >designer has is 1.2 * 3,000^0.5. If that takes them into the 0.17 area so be >it. > >Chris Cahill, PE* >Senior Fire Protection Engineer, Aviation & Facilities Group Burns & >McDonnell >8201 Norman Center Drive >Bloomington, MN 55437 >Phone: 952.656.3652 >Fax: 952.229.2923 >[email protected] >www.burnsmcd.com > >Proud to be one of FORTUNE's 100 Best Companies to Work For *Registered >in: MN > > > > > >-----Original Message----- >From: [email protected] >[mailto:[email protected]] On Behalf Of >[email protected] >Sent: Tuesday, April 03, 2012 10:18 AM >To: [email protected] >Subject: mixing densities in same calculated area > >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 >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] > >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum >_______________________________________________ >Sprinklerforum mailing list >[email protected] >http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum Todd G. Williams, PE Fire Protection Design/Consulting Stonington, CT 860.535.2080 www.fpdc.com _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum _______________________________________________ Sprinklerforum mailing list [email protected] http://fireball.firesprinkler.org/mailman/listinfo/sprinklerforum
