Automatic sprinkler system can extinguish Class A fires and a small Class B fires. However, for most Class B fire sprinkler systems can not do anything, so that the water spray system was born.

   Water spray fire extinguishing systems are water system category, the automatic sprinkler system is developed on the basis of the system using the spray nozzle under pressure at a certain flow down into tiny droplets of water for fire fighting or a protective cooling fixed fire extinguishing system. When a fire occurs if not fire or protective cooling will cause greater damage or serious consequences, so the water spray system must not only ensure adequate spray spray intensity and duration time, but also to ensure that the system can quickly start spray. Water spray system protection mainly for fire hazard, fire spread fast, fire fighting difficult special facilities or equipment. Not only solid fire fighting, can still be used for fighting liquid fires and electrical fires, and can be used for flammable gases and A, B, C liquid production, storage or handling facilities protective cooling.

1 water spray extinguishing mechanism:

  (A) surface cooling. The same volume of water to form water droplet ejection straight streams shape than when the surface to be discharged hundreds of times, when the water droplets injected into the combustion surface, due to large heat transfer area will absorb large amounts of heat rapidly vaporized , the combustion surface of the material temperature is quickly reduced to the required material temperature of thermal decomposition below the thermal decomposition of an interrupt, the combustion is suspended. Depends not only on the surface of the cooling effect of the surface area of ​​the spray droplets, but also depends on the temperature of extinguishing water temperature difference combustible flash, the flash point higher, the temperature difference between the spray water, the greater the cooling effect is better .

  (Two) suffocation. Water droplet formation heated vaporization 1680 times the original volume of water vapor, surrounding the combustion material reduced oxygen content in the air, the combustion will be lack of oxygen or the interruption, to achieve the effect of choking fire instantaneously generated depends sufficient water vapor and completely cover the fire surface.

  (Three) emulsified. Suitable water-insoluble flammable liquid, when the water droplets are injected into the combustion surface of the liquid water-insoluble, due to the impact of the water droplet, causing agitation of the liquid surface, the liquid surface resulting emulsion, emulsion layer as The non-flammable combustion interrupt.

  (Iv) dilution. Water-soluble liquid fire, can be used diluted spray liquid, the liquid is reduced and easier to extinguish burning rate. Extinguishing effect depends on the cooling mist, asphyxia, and the combined effect of dilution.

  Above four acts on the surface of water mist sprayed into the combustion products are usually several roles simultaneously and to achieve the fire. Possess the above-described water spray extinguishing mechanism, so that the water spray with a wide range of advantages, not only in the fight against the fire of solid combustibles fighting efficiency increase of water, and because it is in the form of tiny droplets of water, the fire will cause the fluid splash, can extinguish a flash point higher than 60 ℃ of liquid fire; Further, mist spray nozzle spray droplets are discontinuous discontinuous droplets having the characteristics of high electrical insulation, electrical fires can be extinguished. And protection of combustible gas is widely used in cooling. Commonly used in the protection of plant generating equipment, large transformers, liquefied petroleum fuel storage tanks as well as civil construction, gas boiler room, diesel generator room and diesel pumps and other places of the fire, fire control and protective cooling.

  In civil construction, water spray fire extinguishing system used to protect oil and gas boilers, diesel generators and fuel tanks and other parts of the household. China's "high regulation" provides fuel, gas and diesel generator room, boiler room and the water spray system should be used. Civilian buildings fuel boilers and diesel generators generally use diesel, light diesel oil is usually 0, 0, a small amount of light diesel oil, water spray system can be used. Boiler room fire source point of the tank, the oil pipeline, burner and boiler exhaust pipe explosion at the diaphragm. Generator room fire point of the tank, the oil pipeline and the generator body. Therefore, diesel fuel boiler room and generator room with water spray system to cool fire fighting and protection. Generally use the layout method and three-dimensional arrangement of France. Layout area of ​​law refers to the protection of the net usable area determined by the engine room, spray nozzle evenly arranged under the floor panel. Three-dimensional arrangement of Law for the Protection of area surface area determined by the protected object, mist spray nozzle should completely cover the surface to be protected, set around the spray nozzle around the body. Gas boiler room is usually natural gas, coal gas and liquefied petroleum gas. When the combustible gas leak ignited, only to shut off the gas pipeline valves fire, but can be cooled with water spray protection. Therefore, gas boiler room with water spray system, the purpose is to protect the cooling. Layout design method commonly used to protect the nozzle gas boiler room, its action should be shut off to protect the object of a fuel source.

  Water spray fire detection system in general by the automatic control system high-pressure water supply equipment, deluge valve, water spray nozzles and other components. Spray nozzle mist extinguishing system is an important component parts, the pressure of water in its interior, through the collision, turning, stirring, ejecting tiny droplets of the water spray system has good cooling, suffocation and electric insulation effect . Spray nozzle shall work under pressure in a certain order to form a spray water status. For the same spray nozzle, the working pressure of the higher its water droplet diameter of the smaller, the better atomization. Spray at the same intensity, the atomization effect helps to improve efficiency of fire. Generated mist spray nozzle, the mean droplet diameter of less than 1mm, in general between 100 ~ 700μm.

2 nozzle selection:

  The use of high pressure water spray nozzle atomization nozzle through a variety of forms, ejecting atomized flow can be directly sprayed into the fire area or protected area, used to put out electrical equipment, flammable liquid fires. Nozzle mounted in the horizontal direction according to need, can be mounted vertically. Special specifications spray nozzle, mist as oval, rectangular, mist, etc., can be used to isolate the water curtain. Common spray nozzle into high-speed and low-speed spray nozzle spray nozzle two kinds.

  In a high pressure spray nozzle under the action of the water will flow down into fine mist of water droplets, to a certain speed, according to a certain uniform jet spray angle within range of the corresponding, covering the outer surface of the protected object space on, in order to achieve cooling and suffocation, fire suppression and fire-fighting role. High-speed centrifugal nozzle spray nozzle, droplet smaller, mainly used for fire fighting and fire control. Fire, require spray momentum larger droplet size is small, so the need to provide high pressure spray nozzle, inlet pressure is 0.25 ~ 0.80Mpa, (fog firefighting regulatory requirements, the minimum working pressure nozzle not less than 0.35Mpa), droplet sizes of 0.3 ~ 0.4mm, for extinguishing flammable liquid above 60 ℃. Because of its water droplets are ejected intermittently discontinuous droplets, has good electrical insulation properties, electrical fire fighting can effectively and non-conductive, for the protection of electrical installations using water spray fire extinguishing system. Fuel boiler room and room to set their own generators water spray fire extinguishing system is intended to be the use of such jets.

  Medium impact sprinkler spray nozzle system, coarse droplets. Used to protect the flash point above 66 ℃ flammable liquids, gases and solids hazards, water flow through the spray injection nozzle quickly improve the fire performance. Medium-speed main limiting burning velocity spray nozzle, reduce fire damage and reduce risk of explosion, prompting steam dilution and distribution. During a fire near the nozzle on the fire exposed various buildings located endothermic surface continuous spray mist and prevent the spread of the exposed surface of the heat and fire to protect the safety of various buildings. It is mainly used for cooling protection. Protective cooling spray momentum requires smaller droplet size is large, so need to provide a low pressure spray nozzle, inlet pressure is 0.15 ~ 0.50Mpa, (fog regulatory requirements nozzle working pressure not less than the minimum 0.20Mpa), drop diameter of 0.4 ~ 0.8mm, gas boiler room of water spray system should be used in speed spray nozzle. Impact-type spray nozzle for atomization is poor, can not guarantee water spray electrical insulation properties, it does not apply to fighting electrical fires. Each spray nozzle spray angle and flow coefficient varies, design should be based on the performance parameters of the nozzle or curve use the appropriate nozzle.

3 spray nozzle is calculated:

  Spray nozzle flow rate calculated by the following formula

  q = K (10P) 0.5

  q - spray nozzle flow rate (L / min)

  P - spray nozzle working pressure (Mpa)

  K - spray nozzle flow coefficient, the value provided by the manufacturer (Mpa) spray nozzle quantity calculated by the following formula

  N = S * W / q

  N - protected object calculated mist nozzle

  S - protected object protected area (m2)

  W - protected object design spray intensity (L / min? M2)

4 spray nozzle arrangement:

  Spray nozzle and the number of mounting height and angle of the direct impact extinguishing effect. Reasonable layout of spray nozzles, spray evenly can make the object completely covered and protected to ensure that the spray intensity. Nozzle arrangement and design should be based on the number of spray strength, protecting the area and spray nozzle flow characteristics to determine; spray nozzle according to the position of the nozzle spray angle, spray directly impact the effective range to meet the protected surface and completely covered the surface to be protected . The design principle of the water spray area method.

  When you press the rectangular arrangement, the distance between the spray nozzle should not exceed 1.4 times the mist spray nozzle conical bottom radius; when a diamond arrangement, the distance between the spray nozzle should not exceed 1.7 times the spray nozzle mist conical bottom radius; spray cone bottom radius:

  R = B? Tg (θ / 2)

  R - spray cone bottom radius (m)

  B - spray nozzle orifice and the distance between the object of protection (m)

  θ - angle spray nozzle atomization

5. System design parameters:

  Spray angle: spray nozzle spray mist formed around the axis of the nozzle expansion cone whose apex angle spray nozzle spray angle. θ ranges 30,45,60,90,120. Effective range: spray nozzle is the effective range of the level of injection nozzle, the spray reaches the highest point and the horizontal distance between the nozzle. System design parameters also include the design spray intensity, continuous spray time, spray nozzle operating pressure and system response time, and under the water spray system protection purpose and object of protection class selection.

6 Summary

  There are four water spray fire extinguishing function. Wherein the cooling, emulsification and dilution effect only local fire, asphyxiation due to the limited amount of steam produced, it can only be considered from the local fire-fighting role. So the water spray is a topical extinguishing systems, sprinkler heads must be sprayed into the protected object. But the water itself does not have automatic water spray activated feature, you must come with attached boot the system. Commonly used in automatic fire alarm system, the first catheter system. In addition, compared with the sprinkler system, water spray system caused by water droplets smaller than the large surface area per unit time absorb more heat, so as to achieve the purpose of fighting as soon as possible. Therefore, the system is not only safe, reliable, economical and practical, but also has wide application, fire, high efficiency advantages.