Extinguishing mechanism
Water mist suppresses fire by three combined mechanisms: heat absorption (vaporisation), oxygen displacement (steam expansion 1:1700), and radiant heat blocking. Droplets Dv99 ≤ 1000 µm (per NFPA 750 Class 3) or ≤ 200 µm (Class 1).
Pressure classes
Low pressure < 12 bar: simple piping, large droplets, similar to fine-spray sprinklers. Intermediate 12–34 bar: improved penetration. High pressure ≥ 35 bar (often 70–140 bar): small droplets, deepest penetration; needs stainless tubing.
Best applications
Marine machinery spaces (IMO MSC.1/Circ.1387), historic buildings (low water damage), turbines and combustion engines, road tunnels, kitchen hoods (UL 300A).
Limitations
Water-mist systems are typically zone-specific and require full-scale fire test data per the enclosure. Not a drop-in replacement for sprinklers in storage occupancies.
Quellen
- NFPA 750 (2023)
- EN 14972-1 (2020)
- IMO MSC/Circ.1165
- APA
- FireTwin AI (2026). Water mist systems (low / intermediate / high pressure). FireTwin AI. https://firetwin.eu/de/learn/water-mist
- IEEE
- FireTwin AI, "Water mist systems (low / intermediate / high pressure)," FireTwin AI, 2026. [Online]. Available: https://firetwin.eu/de/learn/water-mist