ESFR Warehouse Plan Review: Clearance and Supply
A 100,000 ft² single-story warehouse has a 36 ft ceiling and is proposed for 34 ft high-piled storage of Group A plastics in cartons. The design uses ESFR K-25.2 sprinklers at 52 psi and 12 sprinklers in the remote area. The submitted hydraulic calculation shows a demand of 2,180 gpm at 55 psi at the riser, plus 250 gpm hose. The water supply flow test shows 2,400 gpm at 20 psi. The plans show 18-inch flue spaces and no in-rack sprinklers. The building official is reviewing the permit application. The owner wants to increase storage to 34 ft immediately; the ceiling has 36 ft clear height and the ESFR deflectors are at 35 ft 6 in. The plan reviewer notices the storage height and asks for a code review.
1. Identify two plan review deficiencies in the submitted design.
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Two deficiencies. (1) ESFR clearance: the deflectors at 35 ft 6 in leave only 18 in above 34 ft storage. ESFR requires a minimum 36-in clearance between the deflector and the top of storage; the design is at half the required clearance. (2) Water supply: the ESFR demand is about 12 × 25.2 × sqrt(52) = 2,180 gpm, plus 250 gpm hose = 2,430 gpm, but the flow test shows 2,400 gpm at 20 psi. The demand is higher than the available flow at 20 psi and at 55 psi, so the supply is inadequate.
2. Calculate the ESFR demand and compare it with the reported supply.
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K = 25.2, P = 52 psi, Q per head = 25.2 × sqrt(52) = 25.2 × 7.211 = 181.7 gpm. 12 heads = 2,180 gpm. Add 250 gpm hose = 2,430 gpm. The submitted demand of 2,180 gpm at 55 psi appears to omit the hose allowance in the comparison. The flow test available at 20 psi is 2,400 gpm, which is less than the 2,430 gpm demand, and the pressure at 2,430 gpm would be below 20 psi. Therefore the supply cannot support the design. The reviewer should reject the hydraulic calculation and require a fire pump, larger main, or revised design that still meets ESFR criteria.
3. What corrections and approvals are needed before the permit can be issued?
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Before approval: reduce storage height or raise the ceiling/deflectors to provide at least 36 in clearance; provide a revised hydraulic calculation including hose allowance and the actual supply curve; verify the commodity classification and ESFR acceptability for Group A plastics; confirm high-piled storage permit requirements; and require a licensed contractor and approved plans. The owner cannot simply increase storage to 34 ft; the plan reviewer should issue a denial or conditional approval with these corrections.