Is the water mist nozzle open or closed?

Water mist nozzles can be divided into open and closed types according to the nozzle type. There is a difference between open water mist nozzles and closed water mist nozzles. Open nozzles are mainly used in open water mist systems, while closed nozzles are used in closed water mist systems. In addition, the structural composition, working principle, market price, etc. of open and closed water mist nozzles are also different.

1. Classification of fine water mist nozzles

1. According to the action mode, it is divided into open water mist nozzles and closed water mist nozzles;

2. According to the principle of fine water mist generation, it can be divided into impact type water mist nozzles and centrifugal fine water mist nozzles;

3. According to the number of openings, the nozzles of the water mist fire extinguishing system can be divided into single-hole fine water mist nozzles and multi-hole fine water mist nozzles according to the number of openings;

4. According to material classification, the nozzle material of the water mist fire extinguishing system can be divided into stainless steel water mist nozzles and brass water mist nozzles;

5. According to the applicability classification, the applicability of fine water mist nozzles can be divided into general nozzles and special nozzles;

6. Classified by function, fine water mist nozzles can be divided into special fire extinguishing nozzles, cooling protection nozzles and water mist blocking nozzles.

2. Open type water mist nozzle

An open water mist nozzle is a nozzle that is in an open state (no water inside). It only turns on the water spray when a fire occurs. It consists of nozzle body, nozzle, nozzle core, filter and other parts.

When water is sprayed through an open water mist nozzle and formed on a plane 1m downward from the nozzle axis, the droplet diameter Dv0.50 is less than 200μm, and the Dv0.99 is less than 400μm. In other words, 99% of the droplets on this plane have a diameter of less than 400 μm, and 50% of the droplets have a diameter of less than 200 μm.

3. Closed water mist nozzle

The closed water mist nozzle includes a nozzle shell, a temperature-sensitive glass ball, a piston rod, a spring, a number of nozzle bodies, joints and a filter frame. It is an important component of a high-pressure water mist closed fire extinguishing system. It can cool the fire plume through fine droplets, isolate water vapor from oxygen, and weaken radiant heat to control and extinguish fires.

The fine water mist sprayed by the closed water mist nozzle belongs to Class I water mist, Dv0.9 ≤ 100μ, with high pressure and good diffusion effect. The residence time of the water mist after spraying is long. Compared with other nozzles, it can reduce the spray intensity of fire extinguishing and fire control and consume less water.

4. The difference between open and closed water mist nozzles

1. The closed automatic sprinkler fire extinguishing system uses a closed sprinkler head, which is a normally closed sprinkler head. The temperature sensing and locking device of the sprinkler head will only fall off and open the sprinkler head under a predetermined temperature environment. Therefore, when a fire occurs, this sprinkler system will only turn on the nozzles that are in the flame or near the fire source to extinguish the fire.

2. The open automatic sprinkler fire extinguishing system uses an open sprinkler head. The open sprinkler head does not have a temperature sensing or locking device and is in a normally open state. When a fire occurs, all open sprinklers in the system protection area where the fire is located will emit water to extinguish the fire.

3. The valve part and the nozzle part of the open sprinkler system are different. The valve part is electric or manual. When a fire occurs, the fire alarm system will alarm and link the control device to electrically start the valve, or manually start the valve, so that the valve opens, and the water from the main pipe reaches the nozzle through the valve and is sprayed out to extinguish the fire.

4. The closed valve is usually closed, but there is water in front and behind the valve. When a fire occurs, the high temperature causes the glass bubble of the closed sprinkler to rupture. When the water spurts out, the valve detects a decrease in water pressure at the rear, thus sending a warning signal to the alarm system, which then activates the fire pump to supply water.

5. The similarity is that they all belong to automatic sprinkler systems, and both fire pumps must be started in conjunction. The difference is that the action steps of water spraying are different, and the application places are also different. Because the stability of the closed type is not high, the nozzle may be broken by external force, causing mis-spraying, so it is set in some parts that are not sensitive to water.

Water mist nozzles are widely used in spray equipment and are usually installed in production sites, warehouses, shopping malls, hotels, hospitals, theaters, office buildings, high-rise buildings, garages and other places with fire risks. There are two types of water mist nozzles: open nozzles and closed nozzles, each with its own advantages. Customers can choose a suitable water mist nozzle according to their own needs.