Design density & area of operation
| Standard | EN 12845 |
| Hazard class | Light Hazard (LH) |
| Density | 2.25 mm/min |
| Area of operation | 84 m² |
Typical occupancies
- Schools
- Prisons
- Religious buildings
What this means for a real project
EN 12845 Light Hazard (LH) 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.