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Module 12 · Hazard Classification

Hazard Classification

NFPA 13 occupancy hazard classification (Light, Ordinary Group 1/2, Extra Hazard Group 1/2), storage commodity classification (Class I-IV, plastics, high-piled storage), and how classification drives density/area design criteria.

Every NFPA 13 sprinkler design starts with a classification decision that every downstream hydraulic calculation depends on entirely. This module works through Light Hazard, Ordinary Hazard Group 1 and 2, and Extra Hazard Group 1 and 2 occupancy classifications and the density/area curve each one maps to, then the separate commodity classification system — Class I through IV, Group A/B/C plastics, and high-piled storage — that storage occupancies use instead, and why the two systems exist side by side.

By the end of this module you should be able to explain why a classification error isn't a minor correction but a change to the fundamental input every pipe size and pump selection downstream was calculated from.

Free related reading in this studio
→ Article: NFPA 13 Automatic Sprinkler System Design→ Concept Explainer: Design Density vs. Design Area→ Sprinkler Hydraulics Calculator (NFPA 13)

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