Density/area design criteria and K-factor sprinkler discharge calculation for terminal ancillary buildings (NFPA 13-2022, §19.2, §7.2.2)
◉ NFPA 13-2022 §19.2, §7.2.2 STYLE CHECK · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. Covers the density/area design method for occupancy hazard fire control (§19.2.3) and sprinkler discharge characteristics (§7.2.2) — the foundational sizing basis for a hydraulically calculated sprinkler system. Full hydraulic calculation (pipe friction loss via Hazen-Williams, remote-area node analysis, water supply curve matching) is not covered here; this gives you the design density/area target and per-sprinkler discharge, which feed into that fuller calculation. Verified directly against this edition's page images. Relevant to terminal ancillary buildings (warehouses, workshops, control buildings) rather than the tanks themselves.
Identification
Research entries stay private to you for practice/testing. Switch to Official once this is a real design your company should see.
Density/Area Design Criteria (Table 19.2.3.1.1)
Each hazard classification has two density/area points on its design curve; the standard's own footnote ties the alternate point to §19.2.3.1.5 conditions.
Q = K√P. CMSA/ESFR sprinklers require a minimum K-11.2 (§7.2.2.5). K-factors above K-28.0 increase flow in 100% increments relative to K-5.6 (§7.2.2.3).
Result
Discharge per sprinkler Q—
Total discharge, all sprinklers in area—
Pipe Schedule Water Supply Reference (Table 19.2.2.1)
For light/ordinary hazard occupancies protected by pipe-schedule-sized systems (not hydraulically calculated) — a simpler, more restrictive design basis than the density/area method above.
Result
Light hazard15 psi (1 bar), 500–750 gpm (1900–2850 L/min), 30 or 60 min duration
Ordinary hazard20 psi (1.4 bar), 850–1500 gpm (3200–5700 L/min), 60 or 90 min duration