Would appreciate if you guys would weigh in on this disagreement I'm having.
The project is subject to military code UFC 3-600-01 for Sprinkler Design Area and Design Density. Otherwise, NFPA 13-2016 applies to all other aspects of the system fire sprinkler design.
Description of System:
The system consists of a 1,000 sqft Ordinary Hazard Design area, surrounded by a larger (remainder of building) Light Hazard design area (these adjacent hazards are separated by full height walls that are capable of preventing a fire on one side from fusing sprinklers on the other side). Per UFC, the corresponding discharge densities should be 0.20 gpm/sqft over 2,500 sqft for the Ordinary Hazard design area, and 0.10 gpm/sqft over 1,500 sqft for the Light Hazard Design Area.
In accordance with the example provided in NFPA 13 Section A11.1.2, the size of the operating area for hydraulic calculations is determined by the Occupancy of the larger surrounding area. In this case, the hydraulic calculation design area is 1,500 sqft based on the larger surrounding light hazard area. A 0.20 gpm/sqft density would be provided for the 1,000 ft2 Ordinary Hazard design area, with a 0.10 gpm/sqft density for the remaining area.
The difference in opinions for this situation is about how to apply NFPA 13-2016 section 184.108.40.206.5 to this situation.
NFPA 13-2016 220.127.116.11.5 Where the total design discharge from these operating sprinklers is less than the minimum required discharge determined by multiplying the required design density times the required minimum design area, an additional flow shall be added at the point of connection of the branch line to the cross main furthest from the source to increase the overall demand, not including hose stream allowance, to the minimum required discharge.
The required minimum design area as referenced in 18.104.22.168.5 should be the SAME design area that was utilized for the hydraulic calculations as determined by NFPA 13 Section 11.2.1. In this case the minimum design area would be 1,500 sqft.
Even though the remote area size was determined to be 1,500 sqft per section 11.2.1, the required minimum design area as referenced in 22.214.171.124.5 should be the minimum design area for the smaller, higher hazard area. In this case, the minimum design area should be 2,500 sqft based on the Ordinary Hazard design requirements. So if the flow from the 1,500 sqft hydraulic calculation is less than 500 gpm (2,500 sqft x 0.20 gpm/sqft), then an additional flow will need to be added to the remote area to bring the flow up to 500 gpm.
Which of the opinions do you feel is appropriate for this scenario?
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