Fire Flow Requirement Calculator

Calculate required fire flow per ISO/PPC methodology based on building construction, area, and occupancy.

Input Parameters

Results

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Needed Fire Flow (NFF)
gpm
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Required Duration
hours
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Total Water Required
gallons
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Min Residual Pressure
psi
Note: The ISO/PPC fire flow methodology is used by insurance rating organizations to evaluate community fire protection. The Needed Fire Flow (NFF) determines water supply requirements and affects insurance premiums. Credits are given for sprinkler systems and other fire protection features.

Reference

ISO Needed Fire Flow (NFF) = Ci x Oi x (Xi + Pi) Ci = Construction Factor = 18 x F x sqrt(Ae) F: Class 1=1.5, Class 2=1.0, Class 3-4=0.8, Class 5-6=0.6 Ae = Effective Area = Floor Area x Stories Oi = Occupancy Factor (0.75 to 1.25) NFF rounded to nearest 250 gpm (min 500, max 12,000) Duration: 2 hrs (<=2500 gpm), 3 hrs (<=3500), 4 hrs (>3500) Minimum residual pressure: 20 psi