High pressure water mist system introduction and composition

First, the concept of high-pressure water mist

Backpack type high pressure pulse pressure spray gun

"Water mist" refers to the concept of "spout mist". The so-called fine water mist is a type of water fine particles generated by using a special nozzle and high-pressure water jet. In NFPA 750 ( United States Fire Protection Federation), the definition of water fog is: at the minimum design work pressure. At a distance of 1 meter from the nozzle , the diameter of the coarsest part of the water spray measured Dv0.99 ≤ 1000 μm

Second, the classification of fine mist

"Water mist" is divided into three levels according to the size of water mist particles

Grade 1 : Dv ≤ 200 μm

Grade 2 : 200 microns > Dv ≤ 400 microns

Grade 3 : 400 μm> Dv ≤ 1000 μm

Third, the water mist fire extinguishing mechanism

"Water mist" mainly controls the fire, suppresses the fire, and extinguishes the fire through the triple action of cooling, suffocation and heat radiation.

The water mist quickly absorbs heat and is vaporized, causing the volume to expand rapidly, usually reaching more than 1,700 times, thereby reducing the concentration of oxygen in the air.

IV. Classification of fine water mist

1 , according to the work pressure:

Low-level system: working pressure < 12.1MP

Intermediate System: 12.1 >Working Pressure < 34.5MP

Advanced System: Working Pressure < 34.5MP

2 , according to the application:

Completely submerged water mist system

Top application of water mist system

Regional Application of Water Mist System

3 , according to the working medium:

One-way flow water mist system

Bidirectional flow water mist system

4 , according to the water supply method:

Pump type water mist system

Bottle type water mist system

V. Water mist application site

Six, high-pressure water mist system composition

Nozzle

1. The high-pressure water mist nozzle is the core component of the high-pressure water mist fire extinguishing system. Separate nozzles, closed nozzles, separate nozzles, special nozzles for high space, ultra-fine water mist nozzles, etc. Each head contains one or more nozzles from the nozzle body, a nozzle holder, a nozzle, deflector and screen composition, under high pressure, centrifugal, impact, or other mechanical means mist jets into micron-level Mist

2 , layout principles

The water mist nozzle shall be selected reasonably according to the type of protection object and the space height, combined with relevant water mist specifications, and in accordance with the requirements of the corresponding spray strength and spacing.

The maximum arrangement spacing of open type water mist nozzles should not exceed 4m . When the area of ​​the protection area exceeds 500m2 , partitioned application mode should be adopted. For the local application of the water mist system, the water mist should be sprayed directly to the protected object, and the protection area should be determined according to the area of ​​its outer surface. When used outdoors, the influence of wind speed on water mist should be evaluated and the nozzle should be properly encrypted.

When a closed system is used, the number of nozzles controlled by one zone control valve should not exceed 800 , and the area of ​​action should be determined according to 140m2 . The installation spacing of the nozzle should not be more than 3.5m and should not be less than 2.0m . The distance between the temperature sensor of the closed nozzle and the top plate or beam bottom shall not be less than 75mm , and should not be greater than 150mm .

Partition application method When the common nozzle is set at the adjacent part of the partition, the spacing between the nozzles should not exceed 3m , and the row spacing should be 1.5 to 2.5m.

In addition to the specific application of the water mist nozzles, the nozzles shall be arranged in a rectangular and balanced manner. The distance between the nozzles and the wall or horizontal obstacles shall not be greater than half the maximum distance between the nozzles.

Pump group

The high pressure pump unit is one of the core components of the entire system and is the key equipment for generating high pressure water. Usually the main components of the high-pressure pump are made of stainless steel. The moving parts of the pump are lubricated with water or oil. According to different requirements in engineering applications, they are configured as one-for-one, one-for-one or multi-use, and the system is based on the actual situation and the pump group is used. Can achieve a variety of traffic output.

Zone control valve

Partition control valve is divided into open, closed, pre-action several control methods.

The open zone control valve box includes a DC24V normally-closed zone valve (which can be a solenoid valve or an electric valve), a pressure switch, connecting pipes, etc., installed at the inlet pipe of each fire zone. The partition valve is controlled by the fire control center and has two automatic and manual control methods. It can send feedback signals to the fire control center. The zone control valve can manually open the valve when automatic operation fails.

The closed zone control valve box contains a zoned control valve, pressure switch, flow sensing, electrical control box and so on. After the closed nozzle bursts, there is water flowing in the pipeline. The water flow sensor will send the signal to the electrical control box in the valve box, automatically open the control valve, send an alarm signal to the control center and start the high pressure pump set. High-pressure water mist sprays fire from the bursting nozzle.

Water booster

The function of the replenishing pressurizing device is to supply positive pressure to the high pressure pump set (the static pressure water in the tank is pressurized to 0.2 to 0.6 MPa and then supplied to the high pressure plunger pump to ensure high efficiency of the plunger pump).

Pump group control cabinet

The function of the high-pressure water mist fire pump control cabinet is used to control the high-pressure water mist pump unit, the replenishing booster pump, and the regulated pump, and the control cabinet comes with a dual power automatic conversion device. Normally set in the pump room. The control cabinet has automatic and manual switching functions. And can be linked with fire automatic alarm system control. It receives the start and stop commands of the fire control center, controls the start and stop of the water mist fire pump set, and feeds back the pump set operation information to the fire control center.

filter

The filter is used to filter the fire-fighting water provided by the water tank or pipe network to ensure the normal operation of the high-pressure pump, water mist nozzles and various control valves in the system. According to different parts of use can be divided into: water source filter, pipe filter and nozzle filter. Into the tank of the filter accuracy, not more than 200 μ m; the high-pressure pump intake filtration accuracy of not greater than 100 μ m; filtration accuracy of not greater than 10 μ m the intake nozzle.

Stainless steel water tank

Pipe network and accessories

Water mist fire extinguishing system Pipes and fittings are made of Stainless Steel Tubes that meet the system working pressure requirements.

06Cr19Ni10 (S30408) . The Stainless Steel Pipes with a carbon content below 0.80% are to be produced by cold drawing . The stainless steel pipes shall also comply with the requirements of GB/T 14976 for Stainless Steel Seamless Pipes for Fluid Conveying .

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.