Design density & area of operation
| Standard | NFPA 13 |
| Hazard class | Extra Hazard Group 2 |
| Density | 0.40 gpm/ft² over 2500 ft² |
| Area of operation | 232 m² |
Typical occupancies
- Solvent cleaning
- Flammable liquids
- Plastics manufacturing
What this means for a real project
NFPA 13 Extra Hazard Group 2 fixes the pair of numbers — design density and area of operation — that drive the most-remote hydraulic calculation. The pump duty point, riser diameter and pipe schedule all flow from this classification. Pick the wrong class and the entire system is mis-sized.
In FireTwin AI you set the hazard class once per zone; layout, hydraulics and BOM recalculate inline and flag any rule that fails before the design leaves the screen.