Classifications

• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62C—FIRE-FIGHTING
  • A62C99/00—Subject matter not provided for in other groups of this subclass
  • A62C99/0009—Methods of extinguishing or preventing the spread of fire by cooling down or suffocating the flames
  • A62C99/0072—Methods of extinguishing or preventing the spread of fire by cooling down or suffocating the flames using sprayed or atomised water
• • A—HUMAN NECESSITIES
  • A62—LIFE-SAVING; FIRE-FIGHTING
  • A62C—FIRE-FIGHTING
  • A62C31/00—Delivery of fire-extinguishing material
  • A62C31/02—Nozzles specially adapted for fire-extinguishing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
  • B05B1/34—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to influence the nature of flow of the liquid or other fluent material, e.g. to produce swirl
  • B05B1/3405—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to influence the nature of flow of the liquid or other fluent material, e.g. to produce swirl to produce swirl
  • B05B1/341—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to influence the nature of flow of the liquid or other fluent material, e.g. to produce swirl to produce swirl before discharging the liquid or other fluent material, e.g. in a swirl chamber upstream the spray outlet
  • B05B1/3415—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means designed to influence the nature of flow of the liquid or other fluent material, e.g. to produce swirl to produce swirl before discharging the liquid or other fluent material, e.g. in a swirl chamber upstream the spray outlet with swirl imparting inserts upstream of the swirl chamber

Definitions

• the present invention relates to a nozzle, of the type called "open", for fire extinguishing systems employing water mist at low pressure.
• low pressure is intended a pressure not greater than 12.5 bar.
• water mist is intended a cone jet of water having at least 90% of the droplets at 1 m distance from the nozzle characterized by a diameter smaller than 1 mm.
• Water mist nozzles for firefighfing systems are known and are called “sprinkler".
• a jet of water is conveyed into nozzles within which, after hitting a deflector, is divided into a spray of droplets.
• a problem of "sprinkler" firefighting systems is that the water is distributed in droplet of enough large size and, consequently, the sprinkler systems require large reserves of water.
• Another disadvantage of such systems is that the deflector makes the nozzle sensitive to physical shock and possible tampering by spiteful person.
• An alternative solution is represented by systems having nebulized water at high pressure, which operate with water input pressures greater than 35 bar and typically between 00 and 120 bar.
• nozzles have small orifices, to create droplets of suitable size.
• the small holes of the nozzle make it very sensitive to dogging by impurities, which are present in water and pipes. Therefore, it is necessary to make sure that components of the supply system are internally free of solid particles and ensure that the used materials have a high corrosion resistance, since said corrosion could generate solid particles that can dog the nozzle orifices.
• the small size of the drops generated by high pressure systems and, accordingly, the small mass that characterizes them make this technology unsuitable to extinguish fires at high power thermal emissions, in fact, the droplets tend to be easily taken away from flames by air upward movements around the fire. Thus the droplets cannot reach and cool the fuel.
• Aim of the present invention is to realize a so called “open” nozzle for firefighting low pressure water mist systems, which is free from the above described drawbacks.
• the nozzle is characterized in that it comprises an effective "swirl” generator device. Swirl means those vortex and rotational motions that allow the water jet to increase the available kinetic energy, making effective the atomization of the jet in small size droplets.
• an open nozzle is described, the nozzle being suitable for low pressure firefighting systems and having the features as defined in the enclosed independent claim.
• FIG. 1 is a cross section of a nozzle according to a preferred embodiment of the present invention.
• Figure 2 is a detail of the nozzle body of Fig. 1 ;
• Figure 3 is a front view of the guiding insert of the nozzle of Fig. 1 ;
• Figure 4 is a top view of the guiding insert of Fig. 3;
• FIG. 5 is a side view of the guiding insert of Fig. 3.
• a nozzle for firefighting low-pressure water mist systems is indicated as a whole by 10.
• the nozzle is able to create a full cone water mist with opening angle between
• the nozzle can be used for fire protection of confined (e.g., tunnels) and open spaces, in maritime and terrestrial applications, for facilities cooling and for individual machines protection.
• the nozzle 10 comprises a nozzle body 20, made of stainless steel or brass, axisymmetric shaped with respect to an axis X, in fluid communication with the water supply pipes, which are of known type and therefore not shown in the attached drawings.
• the nozzle comprises an inlet opening 21 , for water supplying, an inner cavity 22 substantially cylindrical shaped with a spherical bottom wall 22' having a radius equal to the overall diameter of the inner cylindrical cavity 22 and an outlet opening 23 with rounded edges 23', for evacuation of the water mist.
• the rounded radius of the edges is such as to create an angle ranging between 100° and 120° among the external tangents.
• a groove 24 having a triangular section, with a vertex angle of 90°.
• Such groove creates a sharp corner 24 'on the outer edge of the outlet opening 23, able to favor breakage of the liquid lamina and, therefore, the formation of small size droplets. In this way the size distribution of the droplets through the cone is more uniform.
• the nozzle body 20 is provided with coupling means, in the example in the figure a thread 25, to be steadily fixed to the water supply pipe or to a coupling with said pipe.
• the mounting of a filter consisting of stainless steel mesh can be provided, the filter acting to prevent the impurities passage.
• the nozzle 10 also comprises a guiding insert 30, which is also made of stainless steel or brass, steadily allocated inside the inner cylindrical cavity 22 , having the function to split the water flow into two streams. Said streams assume a composed rotational (“swirl") and axial motion within the cavity 22 before to leak out from the nozzle through the outlet opening 23.
• the insert 30 is locked inside the hollow body by means of an interference with the inner surfaces of the body, which prevents the rotation.
• the insert is realized by means of mechanical working or by a sintering process. As known, one of the mechanisms for extinguishing fires by means of water mist is the temperature reduction.
• the extent of the removed heat depends, obviously, by the volume of water and the diameter of the water droplets: with same amount of water, smaller droplets are able to extract more heat, thanks to the effect of a more favorable surface/volume ratio.
• the droplets of water mist in order to penetrate into the flames, must possess speed and mass such as to overcome the turbulence of the combustion gases emitted by the flames.
• the main nozzle design target according to the present invention is to minimize the operating pressure and the needed water flow-rate, obtaining at the same time a sufficient amount of water droplets with adequate speed and mass.
• the small water droplets can be generated from a suitable atomization, which can be defined as liquid breaking into a light mist that is hanging in the air.
• the atomization is obtained by forming within it an appropriate rotational motion of the liquid.
• the guiding insert 30 is designed to create a full cone atomized jet, providing the flowing through water with a turbulent and swirling motion.
• the insert is configured such as to optimize the fluid dynamics of the water flow, reducing losses and, at the same time, limiting the possibility of passages obstruction.
• the insert comprises a vertical support 31 , with curved surfaces, preferably 1 mm thick and having a width equal to the diameter of the inner cavity 22 of the nozzle body.
• the insert can be locked to translations and rotations within the nozzle body 20 by interference (for example, by means of press-fit operation) or mechanically in any other way.
• the insert 30 also includes two inclined wings 32, having an inclination comprised between 35° and 60° with respect to the vertical axis X of the nozzle body 20 and preferably equal to 54°.
• Each wing 32 has a distal portion 33, which extends beyond the surface of the support 31 and, adjacent to the respective distal portions 33, corresponding openings 34 are located, said openings substantially square or rectangular shaped capable to generate an axial flow, which interacts with the swirling motion of the water generated by the wings, allowing as a final result to have a full cone jet.
• the openings 34 have similar depth and width and, in any case, comprised between 1/7 and 1/5 of the diameter of the guiding insert. Said dimensions guarantee the presence of two passages 35 through which two liquid veins having a purely axial flow are generated. Such configuration allows to reduce the probability of nozzle clogging, preserving its fluid-dynamic efficiency.
• the inner surfaces 36 of the openings 34 are parallel to the wings surfaces 32 and are coplanar with the wing lower surfaces 37. Finally, each of the end surfaces 38 of the wings 32 is coplanar with the surface 39 of the vertical support 31 to which each wing 32 is connected.
• Equipped with this composition of motions (rotational and axial inside the inner cavity 22), the water is then guided through the outlet opening 23 with rounded edges 23' and gives rise to a conical and full jet having half of amplitude, with respect to the axis X, ranging between 40° - 60°.
• nozzles allow to acquire to the firefighting low-pressure water mist systems both the benefits of firefighting sprinkler systems and high pressure water systems.
• low pressure systems present components which are normally used in common sprinklers, and, at the same time, ensure fire protection performances and benefits comparable to those of high pressure water mist systems.
• the present nozzle creates a small dispersion of droplets that quickly evaporating due to the high surface/volume ratio, is able to absorb heat quickly; in addition, the homogeneous atomization generated by the nozzle contains the flame thermal radiance and contributes to fire chocking, by means of a partial process of replacement of oxygen with water in the area surrounding the fire.
• said nozzles 10 are made of steel AISI 303 or AISI 316 or brass, work at operating pressures typically between 3.5 and 6 bar and ensure, against fire, the same performances of traditional sprinkler systems, using a water flow from 30 to 50% lower. This means the possibility of allocating to fire systems a lower reserve of water and, in case of fire, to limit damages to objects and structures reached by the water.
• the nozzle according to the invention with the corresponding low pressure water mist system is indicated, and however not limited, for the protection of industrial and civil, warehouses, conveyor belts, machinery and small paper archives.

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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• 2015
  • 2015-07-31 WO PCT/IB2015/055813 patent/WO2016020811A1/en active Application Filing
  • 2015-07-31 EP EP15770969.2A patent/EP3177368A1/de not_active Withdrawn

Patent Citations (1)

Non-Patent Citations (1)

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