Product Overview of High-Pressure Fine Water Mist Fire Suppression Systems

1 , Introduction

Fine-water‑mist fire‑extinguishing systems use water as the extinguishing medium. They employ specialized atomizing nozzles that, under a specified operating pressure—typically 10 MPa—break the water flow into fine droplets to suppress fires. As a fixed‑type fire‑suppression system, it offers high efficiency, cost-effectiveness, and broad applicability, making it an important alternative to halon‑based systems and promising extensive future applications.

2 Definition of Fine Water Mist

• Fine water mist: Under the minimum operating pressure of the nozzle, measured on a plane 1 meter below the nozzle (or spray gun) axis, the droplet size Dv0.99 is less than 400 μm, and Dv0.50 is less than 200 μm.
• Fine-water‑mist fire‑extinguishing system: A fire‑extinguishing system comprising one or more fine‑water‑mist nozzles, a water‑supply piping network, pressurized water‑supply equipment, and associated control devices, which can discharge fine water mist onto the protected object or space during a fire to extinguish, suppress, or control the fire.

3 Composition, operating principle, technical performance, and installation of fine-water-mist fire-extinguishing systems

3.1 Schematic Diagram of a Fine Water Mist Fire Suppression System

The fine-water‑mist fire‑extinguishing system comprises a dedicated high‑pressure water storage tank, a fine‑water‑mist pump unit (including a high‑pressure main pump, a high‑pressure standby pump, a pressure‑stabilizing pump, a pump‑unit control cabinet, an inlet solenoid valve, an inlet water filter, and an adjustment tank), a make‑up water system, a water supply network, a zone‑control valve assembly for the fine‑water‑mist system, fine‑water‑mist nozzles, high‑pressure fine‑water‑mist piping, and a fire detection and alarm system.

Water mist fire suppression systems are classified into open‑type and closed‑type systems, as shown in Figure 1.

Figure 1: Schematic Diagram of the Fine Water Mist Fire Suppression System

• Operating principle and control mode of the open‑type system: The open‑type system employs open‑type sprinklers. In the standby condition, the high‑pressure water mist fire suppression system maintains a specified pressure—between 0.8 MPa and 1.2 MPa—in the piping network from the pump unit outlet to the inlet of the zone control valve assembly. When the pipeline pressure drops below the pressure‑maintaining pump’s set start‑up threshold of 0.8 MPa, the pressure‑maintaining pump activates, ensuring that the system’s piping remains at a stable pressure within the 0.8–1.2 MPa range. In the event of a fire, the fire detection and alarm system sends an interlock signal to the high‑pressure water mist pump unit control center. Upon receiving this signal, the control center shuts down the pressure‑maintaining pump, starts the high‑pressure water pump, and, after confirming proper operation of the pump, opens the zone control valve assembly. High‑pressure water then passes through the fine‑mist nozzles, where it is atomized and discharged to extinguish the fire. Open-loop systems are simple, highly reliable, and the most commonly used control method. They are primarily employed in applications with a high fire risk, protecting equipment and personnel within the designated area, such as telecommunications equipment rooms, power stations, and oil-immersed transformer installations.
• Closed‑type operating principle and control method: The closed‑type system employs closed‑type sprinklers and typically does not incorporate zone valve assemblies. In the standby condition, the high‑pressure water mist fire suppression system maintains a specified pressure—between 0.8 MPa and 1.2 MPa—throughout the piping network from the pump unit outlet to the water mist nozzles. When the system pressure drops below the pressure‑maintaining pump’s set start‑up threshold of 0.8 MPa, the pressure‑maintaining pump activates, keeping the system pressure within the stable range of 0.8–1.2 MPa. Upon fire occurrence, when the temperature reaches the preset activation threshold, the glass bulb of the closed‑type sprinkler ruptures. Typically, the water‑flow indicator of the alarm system sends a start signal to the pump unit, initiating the high‑pressure main pump while simultaneously stopping the pressure‑maintaining pump. High‑pressure water is then atomized by the water mist nozzles and discharged to extinguish the fire. Closed‑type wet systems are primarily used in areas where fires spread horizontally at a slow rate and can be promptly controlled and extinguished, with personnel as the main protected occupants—such as public spaces and corridors. 

3.2 Model and Technical Specifications

Main technical parameters:

Rated flow rate: (varies depending on the specific model) L/min

Rated pressure: 10 MPa–16 MPa

System power: 30 kW per pump

Operating temperature range: 4°C–50°C

Water storage capacity: 1000 L

Implementation Standard: GA1149-2014

Technical specifications of major components:

High-pressure nine-plunger pump unit: stainless steel, model AP8016A, rated working pressure 14MPa , The rated flow rate of a single pump is shown in the table below.

Partition control valve: stainless steel, maximum working pressure 16MPa，DV24V

Safety valve: stainless steel, pressure adjustment range 8 MPa~14 MPa , maximum allowable flow rate 120L/min。

Fine Water Mist Performance Parameters Table ( Open type, closed type )：

Detailed Diagram of Fine Water Mist Equipment Assembly

1 , high-pressure pump motor, 2 , pressure-stabilizing pump motor, 3 , high-pressure pump, 4 Pressure stabilizing pump, 5 , electrical control cabinet, 6 , water tank, 7 , emergency water supply pipe, 8 , high-pressure discharge pipe, 9 , bracket, 10 , pressure relief and pressure regulating valve, 11 , pressure gauge, 12 , inlet water solenoid valve, 13 , water inlet filter, 14 , pressure transmitter, 15 , high-pressure check valve, 16 , drain pipe, 17 , Float-type level gauge ,18 , pump suction pipe.

Fine water mist nozzle: Model: XSW-FZ 15/16 QX1, XSW-FZ 20/16 QX1, XSW-FZ 25/16 QX1, XSW-FZ 32/16 QX1, XSW-FZ 40/16 QX1, XSW-FZ 50/16 QX1, XSW-FZ 65/16 QX1 The open‑type fine‑mist sprinkler heads are primarily manufactured from austenitic stainless steel. The closed‑type sprinkler heads consist of a series of atomizing nozzles combined with temperature‑sensitive glass bulbs; they produce uniform droplets (DV0.9 < 200 μm) and provide broad spray coverage, effectively reaching the fire’s ignition points and delivering excellent fire‑extinguishing performance. 

High-Pressure Water Mist Fire Suppression System – Frequently Asked Questions

Q: What types of facilities are suitable for high-pressure fine-water-mist fire suppression systems?

A: Suitable for use in distribution rooms, data centers, archives, diesel generator rooms, and similar facilities; capable of extinguishing electrical fires as well as solid- and liquid‑fuel fires.

Q: What is the fire-extinguishing principle of high-pressure water mist?

A: High-pressure atomization breaks water into fine droplets, rapidly absorbing heat to lower the temperature, isolating oxygen, and diluting flammable vapors—multiple mechanisms working in concert to extinguish fires.

Q: What are the activation methods for high-pressure water mist fire suppression systems?

A: Supports automatic activation via fire detector linkage, as well as manual activation on-site; some systems also feature emergency mechanical start-up functionality.

Q: Will high-pressure water mist fire suppression cause short-circuit damage to electrical equipment?

A: The droplet size is extremely small, providing excellent insulating properties; when used in accordance with regulations, it is unlikely to cause a short circuit when extinguishing fires involving energized equipment.

Q: What are the installation requirements for high-pressure water mist systems?

A: Piping and nozzles shall be installed in accordance with the layout of each protected zone to ensure uniform mist coverage; adequate space must be provided for the water source and pump unit, and the piping must meet the required pressure‑rating standards.

Q: What items need to be inspected daily in a high-pressure water mist system?

A: Inspect the pump unit, valves, and piping for leaks; verify that the water tank level is normal; and check the operating status of the detectors and the control panel.

Q: Is the cleanup after high-pressure water mist fire suppression labor-intensive?

A: It consumes extremely low amounts of water and leaves minimal water residue, making post‑fire cleanup much easier compared to conventional sprinkler systems.

Q: Can high-pressure water mist be used for fire suppression in outdoor, open spaces?

A: Not recommended for use in windy conditions or in open, unenclosed areas, as air currents can disperse the mist droplets and reduce fire‑extinguishing effectiveness. It is best suited for relatively enclosed protected spaces.

Q: Does a high-pressure water mist system require continuous water supply?

A: The system is equipped with a dedicated water storage tank, which supplies water during a fire; for long-term operation, it is essential to ensure a stable and reliable make-up water source.

Q: Is the long-term maintenance cost of a high-pressure water mist system high?

A: Regular inspections of the filters, nozzles, and pump units are sufficient; there are no costs associated with chemical reagent replacement, and overall maintenance is relatively straightforward.