Low-pressure, Medium-pressure and High-pressure

In water mist systems, the industry generally classifies systems into three categories—low-pressure, medium-pressure, and high-pressure—based on operating pressure (MPa).

Low-pressure water mist systems: Operating pressure ≤ 1.2 MPa

• Compliant with most international standards, such as NFPA 750, CEN/TS, and China’s Technical Specifications for Fine Water Mist Fire Extinguishing Systems.
• The system structure is relatively simple, allowing for the use of standard fire-fighting centrifugal pump sets, with piping typically made of austenitic stainless steel.
• Used in diesel generator rooms, oil-immersed transformers, cable tunnels, and similar locations; features larger droplet sizes, higher water consumption, and more noticeable water staining effects

Medium-pressure water mist systems: 1.21 MPa < operating pressure < 3.5 MPa (approx. 12.1–3.5 bar)

• The droplet size is finer than that of low-pressure systems, improving cooling and suppression effects, though it still falls short of high-pressure systems.
• Typically requires a plunger pump; operating and maintenance costs are higher than those of centrifugal pumps, resulting in poorer economic efficiency.
• Rarely installed as a standalone system in practical applications; some functions can be replaced by water spray or high-pressure fine water mist systems.

High-pressure water spray systems: Operating pressure ≥ 3.5 MPa

• Capable of producing micron-sized (Dv0.50 ≤ 65 μm) ultra-fine water mist, offering excellent cooling, suffocation, thermal radiation blocking, and electrical insulation properties.
• Widely used in high-value facilities sensitive to water damage, such as data centers, archives, cultural relic repositories, and ship engine rooms.
• The system imposes extremely high requirements on water quality, nozzle precision, and pipe pressure resistance, and often employs two-fluid atomization technology or precision ceramic/stainless steel nozzles.