Fixed water spray application rates and nozzle layout for tank shell cooling, pool fires, and adjacent structural steel (NFPA 15)
◉ NFPA 15-2022 §7.3–7.4 STYLE CHECK · NOT A REGULATORY SUBMISSION TOOL
⚠ Indicative tool only. Rates and spacing limits checked directly against the standard's page images (this source PDF's text layer extracted with heavy OCR-like corruption despite having embedded fonts, so numbers were verified visually rather than trusted from extracted text). This tool computes application rates, water demand, and minimum nozzle-level counts — it does NOT size individual nozzles (K-factor/pressure), since NFPA 15 treats that as listed-nozzle manufacturer data, not a formula this standard itself provides. This is a different tool from the existing Fire Water Demand calculator (OISD-116/API RP 2021) — the two use different source standards and may give different rates; they're not meant to be summed together.
Identification
Research entries stay private to you for practice/testing. Switch to Official once this is a real design your company should see.
Units
Tank / Vessel Shell Cooling (§7.4.2)
Default 0.25 gpm/ft² [10.2 L/min/m²] is the §7.4.2.1 minimum net rate — increase it if your engineering basis calls for more margin.
Horizontal nozzle spacing (§7.4.2.3) must ensure spray patterns meet or overlap around the full circumference — that depends on the specific nozzle's listed spray pattern diameter at the design pressure, which isn't computed here; get it from the nozzle manufacturer's listing. §7.4.2.5: add nozzles around any projections (manways, flanges, brackets, relief valves) that would otherwise block coverage.
Uninsulated Skirt / Saddle Protection (§7.4.2.6)
Result
Water demand (0.25 gpm/ft² / 10.2 L/min/m², one exposed side)—
Flammable/Combustible Liquid Pool Fire Protection (§7.3.3)
For the diked/bunded area around the tank — see the Dike Capacity calculator for the containment area itself.
Default 0.50 gpm/ft² [20.4 L/min/m²] is the §7.3.3 minimum net rate for protected area.