ISO Needed Fire Flow
NFF = Ci × Oi × (1 + X + P) per the ISO Public Protection Classification; Ci = 18 × F × sqrt(A) by construction class. Rounded to 250 gpm; capped at 12 000 gpm.
Formula and source
NFF = Ci × Oi × (1 + X + P) where Ci = 18 × F × sqrt(A_eff). F per construction class (Frame 1.5 / Joisted masonry 1.0 / Noncombustible and Masonry-noncombustible 0.8 / Modified-FR and Fire-resistive 0.6). A_eff = footprint × min(stories, 3) for non-fire-resistive; footprint × 1 for fire-resistive. X = exposure factor by distance band (0.05-0.25). P = communication factor. Output rounded to 250 gpm; floor 500, cap 12 000 gpm.
ISO Public Protection Classification (PPC) Schedule by name. Cited by name only; the schedule's commentary is not reproduced.
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