Devices used to disperse liquids relevant from a standpoint of this innovation are equipped with a reservoir (a pressure vessel) containing some liquid, e.g. water or water-based solutions, and a motive gas ensuring a hydrofore-type mechanism of evacuating said liquid from the reservoir. Such devices, in the upper part, are equipped with a head assembly comprising a control valve and at least one egress channel capped with an exit nozzle, as well as a plunger tube, extending from the head assembly, at least partly into the reservoir. The plunger tube, in its lowermost part, where it almost touches bottom of the reservoir, has an ingress channel, often fitted with a filter, the latter sifting out undesired solid particles, which may damage the head or clog the exit nozzle. The head assembly has various kinds of body fittings; a seat to attach a hose or an exit nozzle, or a dispersion chamber; upstream the exit nozzle, a pressure gauge with an indicator, or a safety-valve; and it may have a variegated layout. In more evolved embodiments of the atomiser (so called "mobile fire-fighting plant") head assembly may be a part of the manifold conjoining two or more liquid phase reservoirs, a vessel holding gas under pressure, a fire hose manifold or an operator's gas mask etc. Devices of such type may be used in fields like, pharmaceuticals, cosmetics, e.g. for skin care; as components of crop-protection machinery; in disinfection or construction, to surface-protecting or impregnating materials or structures.

Fire extinguishers are a special case of the device under consideration. Extinguishers charged with water (or any different incombustible liquid) and filled with a motive gas, where a highly dispersed plume of mist, adequate for fire suppression applications is achieved, and meeting the regulatory requirements for portable or mobile fire extinguisherfire extinguishers are referred to as the water mist fire extinguishers. Usually in such fire extinguishers two-phase flow is not employed, and the dispersion level is realised due to a proper construction of an exit nozzle.

Electric conductivity of an extinguishing stream is a problem of all water fire extinguishers, complete with a high post-fire damage due to a fire suppression aftermath. Mist fire extinguishers (and especially water mist extinguishers employing pure water) are helpful in eliminating these inconveniences, while simultaneously advantages of water as an easily accessible, cheap and environmentally-friendly extinguishing agent are retained. Additional advantages of fire mist include a possibility of suppressing all classes of fires, apart from fires of combustible metals (class D); absence of corrosion in a vicinity of conflagration, sufficient amount of oxygen in an ambient air neighbouring the fire to permit breathing, removing smoke from the surroundings, creating a protective mist-shroud thermal screen protecting an operator and bystanders, non-cracking of hot cast-iron casings or similar elements (elimination of a thermal shock) subject to a fire suppression when water mist is used, low kinetic energy of fire-effective mist allowing for extinguishing live people.

However, existing designs of typical portable water fire extinguishers encounter a barrier of a limited quantity of motive gas indispensable to disperse water to a degree of a fire mist. Two venues of generating mist are practicable. First, is a dynamic breakup of the Iiquid stream, when a single-phase feed stream reaches the exit nozzle, more seldom - reaching a dispersion chamber, which requires ensuring relatively high pressure values. The second venue, and such was applied in the device according to invention, is taking advantage of a two-phase flow to disperse a Iiquid, where required pressures values at the supply side are lower.

In the international patent application WO2007006987A1 presented device is equipped with a syphon tube having one opening or several openings, located above a free surface of a liquid, on the same height; an influx of gas into a stream of liquid agent inside the tube generates a two-phase flow in a form of bubbles of gas carried by a torrent of the iiquid. The authors do not relate to the required parameters for the openings in syphon tube in any detail and propose no additional of improvements of the device. At motive gas (nitrogen) pressure of 15 bar, for a 10-litre capacity cylinder filled with 3 litres of water, the dispersion of water attained droplet size be!ow 400 micrometres, and the stream of mist reached 8 m, whereas the duration of device operation was 25 seconds. The authors hinted problems associated with calibration of the device, e. g. a possibility of excessive ramming the syphon tube with gas. For a case of an extinguisher use, represented in there, only less than 1/3 of a reservoir was filled with an extinguishing agent (water), an aftereffect of lack of any gas management and a subsequent necessity to assure a surplus of gas.

In the international patent application WO201101 1087383A1 (also Polish application P. 390 70) a device to regulate two-phase flow was introduced. The crux of this device concept is an incorporation of a bladed rotor having a special layout; and separate gas and liquid supply lines, organised in a counter current scheme. The feeding gas line is blinded on one end, has side openings to ensure a graded gas proportioning, however the process of creating of a two- phase flow takes place in a mixing chamber of the rotor only, whereas this outflow remains a plug-type throughout almost entire duration of a process, except at the end of the discharge the flow changes to a dispersive type, during the phase of a cylinder blowthrough.

Different types of dispersive exit nozzles, including effervescent nozzles introduced at the end of last century, are found in atomisers, nebulisers, injectors and burners.

In the particular patent applications US20 20241535A1 and US20140138 02A1 examples of improved, effervescent dispersive nozzles were introduced. Under condition that the feeding two-phase flow is adequate, for such nozzles rates of consumption of gas per liquid input are usually the smallest possible.

An example of a collision-type dispersive nozzle, where exiting streams are forced to collide, is presented in description of the utility design PL65131 Y1.

Because of important benefits all mist fire extinguishers entail there is a persistent demand for improvement of these devices. For a fire extinguisher working in a two-phase supply reg ^: me efficiency of the process of dispersal of liquid during the whole discharge process has a fundamental importance, however in the solutions present d herein this issue was not systematically related to any form of a gas management process.

A device ensuring a two-phase flow in a liquid atomiser, equipped in its upper part with a discharge control assembly, the device contains at least one egress channel, as well as a plunger tube, placed below this assembly and interconnected with this assembly, the plunger tube having in its lowermost section an ingress channel, optionally outfitted with a filter to keep away impurities, and interconnected with a discharge control assembly, and further downstream with an egress channel, according to the invention, is characterised in that the plunger tube is outfitted with a liquid flow restrictor and, above the latter, a row of side openings connecting external space of the tube with its inner channel, where the successive side openings are positioned longitudinally along the tube at different distances from the restrictor.

In a preferred embodiment the side openings are positioned on the tube so that the reciprocal perpendicular distance between the adjacent openings increases when approaching the upper part of the device, and such arrangement of the openings applies at least to a part of the tube.

It is preferred that the tube is set vertically.

It is preferred that the openings are positioned on the tube along at least one line skewed or helical with respect to the longitudinal axis of the tube.

It is preferred that the restrictor complete with a filter to keep away impurities is a separable unit placed on an inlet of an internal channel of the tube.

It is preferred that the restrictor has a form of a narrow gorge, or a form of an orifice or at minimum of a partial transverse barrier in the inner channel of the tube, or a cruciform stack of several such partial barriers, or a form of a bushing having diametersmaller than the diameter of the inlet of the tube.

A liquid atomiser equipped with a reservoir of a liquid phase and a source of gas under pressure, in a form of a void over the free surface or a cartridge, or an external container, as well as a device ensuring a two-phase flow in an atomiser of liquid, equipped in its upper part with a discharge control assembly, the device contains at least one egress channel; as well as a plunger tube, placed beiow this assembly and the tube interconnected with this assembly, the plunger tube having in its lowermost section an ingress channel, optionally outfitted with a filter to keep away impurities, and interconnected with a discharge control assembly, and further downstream the control assembly with an egress channel and the nozzle, according to the invention, is characterised in that the plunger tube is outfitted with a liquid flow restrictor and, above the 'after, a row of side openings connecting the external space of the tube with its inner channel, where the successive side openings are positioned longitudinally along the tube at different distances from the restrictor.

It is preferred that side openings are positioned on a tube so, that reciprocal vertical distance between the nearest two openings increases when approaching the upper part of the device, and such arrangement of the openings applies at least to a part of the tube.

It is preferred that the atomiser is a mist fire extinguisher, with a water charge.

It is preferred that the exit nozzle is a multichannel collision-type nozzle, and its exit channels have conical or ferrule outline, having diameters tapered towards the exit.

It is preferred that the nozzle is a composite-type comprising a chassis, onto which the front plate containing exit channels is attached, as well as, placed at some distance away from the front plate, a stator plate, having pass- through channels, and both plates limiting a packing chamber of the composite nozzle.

A method of conversion of ε liquid atomiser equipped with a reservoir of a liquid phase and a source of gas under pressure, in a form of a void over the free surface or a cartridge, or an external container, as well as a device ensuring a two-phase flow in a liquid atomiser, equipped in its upper part with a discharge control assembly, the device contains at least one egress channel; as well as a plunger tube, placed below this assembly and interconnected with this assembly; the plunger tube having in its lowermost section an ingress channel, optionally outfitted with a filter to keep away impurities, and the tube interconnected with a discharge control assembly, and further downstream the control assembly with an egress channel and the nozzle according to the invention, is characterised in that, on the plunger tube the liquid flow restrictor is mounted by means of a tight glue, a welded or a threaded connection, and above said restrictor a row of side openings connecting the external space of the tube with its inner channel are made, where the successive side openings are executed longitudinally along the tube at different distances from the restrictor.

A particular embodiment of the subject of invention is represented in a drawing, wherein in Fig. 1 a general view of a liquid atomiser is presented, as a variant having motive gas stored in a reservoir containing liquid, above free surface of liquid, and a plunger tube having openings complete with a flow restrictor, in Fig. 2A a device generating a two-phase flow in a liquid atomiser is presented, wherein this device is conjoined directly with a discharge control assembly, the latter comprising a plunger tube complete with a flow restrictor in a form of a unit integrated with a filter, in Fig. 2B a similar device as in Fig. 2 A is presented, however the flow restrictor has form of a narrow gorge on tube, and the filter is arranged as a separate part, and in Fig. 3A the flow restrictor is presented as a unitary element containing a filter. Moreover, in Fig. 3B a plane A-A from Fig. 3A cross-section of this unit is presented, !n Fig. 3C flow restrictor downstream side, in Fig. 3D its upstream side is shown. In Fig. 4A a preferred example of a composite exit nozzle is shown, as a lateral section, where the stem is adapted to mount the nozzle on a hose. In Fig. 4B a chassis of the nozzle from Fig. 4A is show, but in a form adapted to mounting directly on a body of an actuation valve. In Fig 4C a view of an external (front) plate of the nozzle assembly is presented from the downstream side (the Sower drawing) and a view of a stator plate from the downstream side (the upper drawing), and in Fig. 4D a view of an external plate from the upstream side (lower drawing) and of a stator plate from the upstream side (upper drawing), in Fig. 4E a side view of an external plate (the lower drawing) and a side view of a stator plate (the upper drawing), in Fig. 5 different kinds of liquid atomisers, e.g. fire extinguishers are shown, consecutively: a stored pressure atomiser, where the gas is stored (held) in a common container (a pressure vessel) holding also a fluid, having an exit nozzle connected to the device via a hose; a homonymous atomiser having an exit nozzle connected directly to the body of the main valve; an atomiser having an internal cartridge holding gas and an exit nozzle connected to the device via a hose; an atomiser with an external reservoir of gas, equipped with a manifold assembly and equipped with an exit nozzle connected to the device via a hose; an atomiser being an aggregate of two containers holding a liquid conjoined via a manifold, and an exit nozzle connected to the device via a hose; an atomiser arrangement in a form of a fixed system, e.g. fire suppression installation, having a remotely controlled actuation mechanism and a system-type (rigid) conduit leading to the exit nozzle.

Well-known, typical liquid atomisers contain pressure reservoir 1 in which a liquid agent is stored 2, and gas under pressure 3 is held above it, in first example of embodiment, or in second proposed embodiment - part of gas under a moderate pressure and motive gas in internal cartridge, or in an external container, in the third example. The discharge control unit 4 comprises a valve placed topside of the pressure reservoir, whereas a plunger (aspiration) tube 5 is attached to the bottom part of that valve body, and the former extends downward the reservoir inner space. The lowermost part of the tube or the tube ingress channel is outfitted with a filter, e.g. a wire mesh type, to keep away solid particles. Discharge-control unit containing at least one egress outlet conjoined with an exit nozzle 8, which may be attached directly or via a flexible hose.

A device ensuring a two-phase flow in a liquid atomiser, according to invention is distinctive in terms of the fact that the plunger tube 5 in its bottom part, or in the end is outfitted with a flow restrictor 6 and, above it, with a row of pass-through openings, connecting external space of the tube 5 with its inner channel. Positioning of openings with respect to the location of free surface inside the atomiser ready for discharge is very specific - most or ail openings are placed below this height, and access of gas to consecutive openings is effected by the fall of free surface during the discharge of the device. Openings are orientated perpendicularly to the tube wall surface and have diameter sizes between 0.5 to 3mm. It is preferred that the openings are not positioned (situated, placed) along one vertical line, one above another, so that the gas bubbles entering the inner channel of the tube, where the flow is either liquid or the two-phase type, do not coalesce extensively. It is possible, as an option, to install in this device a filter to keep away solid particles, in one example of embodiment it can be distinct bushing 6a (as shown in Fig 2B) on a plunger tube 5, or be integrated with the restrictor 6 to make up one demountable element (as shown in Fig. 2A). Such restrictor may encompass a shell 10 inside whbh a filter 1 1 is placed, where an outside threaded connection 12 is used to connect this shell to the plunger tube 5. Reduced passage 13 is created by way of crossing barriers 14 of a restrictor. Such an example of the restrictor layout is shown in Figs. 3A, 3B, 3C and 3D.

A special configuration of an exit nozzle is proposed for the purpose of this invention - this is a composite nozzle, where a multistage process of preparation of two-phase medium and a dispersal of liquid to the stratum of an effective fire mist during the entire discharge process of the device takes place. The composite exit nozzle, embodiments as shown in Figs. 4A, 4B, 4C, 4D and 4E comprises a chassis 15, an exterior element - a front plate 16 furnished with exit channels, as well as interior element - a stator plate 17 having pass- through channels. In the void in-between the said two plates (16, 17), a free space is created, this is a preparatory chamber 18, a notion somewhat similar to a remixer concept, where a process of a partial re-homogenization of the two-phase ^f eed flow takes place, by way of elimination of larger bubbles of the gas phase, when this flow attains the state of a heavy foam, prior to the two- phase flow reaching the inlets of the exit channels in the front plate. The front plate and the stator plate are placed parallel to each other, in a certain distance and may be conjoined with the chassis by a threaded connection.

The side openings in a plunger tube may have an arbitrary distribution, however the preferred setting (positioning) of them on the tube is along a slanting, broken or a helical line in relation to the longitudinal axis of the tube. The tube is set vertically, for the sake of this invention understood as plumb in relation to the ground, so that the bubbles of gas exiting from the openings, under action of buoyant force accelerate one with respect to the next, towards the top of the tube. The plunger tube is usually rigid and made of some artificial raisin, but realisations of the tube using different materials, e.g. metal or pliant materials are also practicable. The side openings, majority of which at the moment of activation of the device is under the level of free surface of a liquid, are positioned at different heights with regards to the upper end of the tube, because the process of discharge of the device causes the free surface to fall together with the pressure of the motive gas. This arrangement follows from a fact that the tube has to ensure a controllable and altering volumetric ratio of inflowing gas and liquid phases for the duration the entire discharge process, such proportioning is necessary for a correct operation of the effervescent dispersive nozzle. The distribution of openings in tube is degressive in the direction of the restrictor that is they became more compressed towards tube's bottom end, however excluding certain section at its tip {near the low extremity of a reservoir). Along the section where this interspace grading applies, distance between and adjacent openings, measured in plumb, increases in the direction away from the restrictor. Increase of said distances should be understood as a magnification of at least 5 or 10%. This trend applies along ¾ to as much as 4/5 or 5/6 the length of the tube, calculated from the topside that is where the tube is set in a discharge control unit. Close to the upper part of the device, in a vicinity of the of a discharge control unit, the tube is void of openings. Good results for this device are achieved when the openings are set (positioned) along a helical line and especially, two helical lines in a "boxer" arrangement, meaning placed along opposite lines, where each of them sweeps the same 180 degree angle to prevent collisions of bubbles. Nevertheless, quite positive results e.g. for devices not under rules covering fire suppression equipment, are achieved using different allocation of these openings. A liquid flow restrictor is attached at the upstream side of the plunger tube. The liquid flow restrictor is calibrated, that is its configuration, to the effect of reducing the cross-surface area of a liquid stream in relation to the diameter of tube above it, is tailored to many other features of the device, e.g. the initial pressure inside the liquid reservoir, the quantity and the diameter of openings, density of the liquid agent etc. For example when a restrictor is in a shape of a simple orifice set inside some plunger tube, then the pass-through surface area of the tube is reduced by at least 8%, in relation to internal diameter of the tube. The restrictor can have any configuration locally reducing diameter of a plunger tube, !t may have a form of a narrow gorge, or a form of a partial barrier e.g. an orifice or a stack of several barriers. It is possible to realise an embodiment of this invention where both, the restrictor and the filter to keep solid particles away become two distinct and separable elements affixed using a thread connection on a tube.

A device or an atomiser according to the invention are equipped with an exit nozzle. Any exit nozzle may be applied in this device, as long as it generates mist. This may be a single-channel exit nozzle, a Stanley nozzle, or an array of Stanley nozzles. Due to an effect of a rapid growth of the gas phase part (intensity) accompanied by a falling pressure, as in the aspiration plunger tube such a two-phase flow is generated, every such nozzle will generate mist as if it was a purpose-made effervescent nozzle. Taking into account configuration of an atomiser and the preferred parameters of the mist plume, the recommended arrangement is a multichannel nozzle, having cone-formed (exit) channels laid in a collision pattern (a collision nozzle).

The composite exit nozzle has a specific, improved arrangement and performs as an effervescent-type nozzle, but keeps on generating mist in a regime, even though as a result of much augmented gas fraction (gas intensity, concentration) in the two-phase flow, practically this feed flow is inappropriate. In order to ensure correct working parameters of the nozzle for the entire duration of the atomiser discharge cycle, two additional improvements were introduced: a) a packing chamber as well as b) crash point location for exiting streams downstream of the front plate. Introduction of the stator plate improves the mist dispersion rate during the entire discharge process. This way the dispersion process of a liquid phase is effected at several stages - inside the nozzle, but also by way of collision mechanism outside the nozzle, whereas the process of reformulation of the two-phase flow taking place in the packing chamber improves the efficiency of dispersion and the range of an effective nozzle performance.

Exit holes in the front plate are set in pairs directed towards each other to effect collision of streams. Moreover, the openings in the stator plate and exit channels in the front are shifted somewhat or at least part of openings is shifted one versus the other, which improves effectiveness of the packing chamber.

The flow restrictor built into the filter unit (or as a distinct part) creates resistance to the liquid flow, which in turn produces a desired small pressure difference across a wail of the tube. This pressure difference causes gas phase emanating from the openings actually above the free surface of liquid permeation into the inside channel (inside cavity) of the aspiration tube. So- generated two-phase flow, under a considerable pressure is brought to a nozzle where it undergoes atomisation. A stable plume of mist is produced for almost entire duration of a discharge cycle of a liquid charge, only at the end of this cycle a very fine mist appears accompanied by an intense blowdown of a whole system. This is a consequence of a dispersive character a medium (aerosol) reaching the nozzle. This feature is intentional; a result of a modified distribution of the lowermost openings on an aspiration tube, the purpose is a removal of remainders of liquid charge from the pressure vessel.

A device according to invention may be used in various types of fire extinguishers, e.g. stored pressure fire extinguisher or a cartridge-type one, a case where a motive gas is actuated by way of striking a knob just before putting an extinguisher into action. Motive gas can be held inside or outside an extinguisher in a cartridge, in a pressure vessel connected to a reservoir holding liquid via a manifold. In Fig. 5 basic types of embodiment of invention are represented, specifically different types fire extinguishers, which may comprise a device according to invention or as a whole may be an atomiser according to invention.

A method according to invention leads to changing operating modes of well-known atomisers, to advance an improved atomiser by way of adding a liquid flow restrictor and side openings in a plunger tube.

In a device according to invention three principle improvements, which co-validate one another, were harmonised. A dispersive, effervescent type exit nozzie was introduced, to cooperate with an OIG (outside in gas) plunger tube, the tube fulfilling simultaneously a task of changing the dosage (proportioning) of gas and liquid phases, by way of a progressive distribution side-wall openings consecutively exposed during the fall of free surface. Moreover a liquid flow restrictor on the tube was introduced.

It follows from the fact of introduction of a restrictor that after a control valve is opened a relatively small difference of pressure across the wall of the tube is created, this pressure difference causing permeating of gas phase from the opening above the free surface into the inner channel of the tube. The buoyant force acting on bubbles causes them to ascend with a slight acceleration with respect to the followers. Consequently, volumetric intensity of gas inside the aspiration tube gradually increases. Introduction of a helical line and graded addition of gas in part reduces coalescence (merging) of bubbles, when as a result of growth of volumetric intensity of gas the flow becomes a foam type.

Analysing energy balances connected with a dispersal of a liquid stream and relating this to fire-extinguisher principles of operation, specifically to the water mist extinguisher in question, where a typical working pressure is 15 bar (abs.), and which during the discharge process falls to some 1 - 1.5 bar, where the initial water fill rate of a cylinder is 65% authors came to fundamental conclusion, principal from a point of view of the presented solution. An eightfold drop of pressure in a cylinder is mirrored by a drop of water level by over a half of cylinder's height (as related to the entire cylinder height L), but this has to be reflected by a 32 times increase of i volumetric ratio of gas to liquid fractions.

What follows from the above, is that the provision of gas into the stream of liquid must unavoidably be adaptable to a falling pressure inside the cylinder, as effected by the aspiration tube fitted with a liquid flow restrictor, and that the exit nozzle must be tailored to a ferociously growing content (concentration) of the gas phase, but to remain in an effervescent regime of supply as long as possible. The nozzle is placed behind the control valve; therefore the pressure drop across the exit channels of the nozzle should be significantly higher than the one across this valve. Introduction of multichannel nozzle having cone-form channels tapered in in the downstream direction meets this condition.

Additionally, it is preferred to arrange for collisions of the exiting streams (collision-type nozzle), where an surplus of kinetic energy, especially of the gas phase, generated when the volumetric ratio of gas to liquid fractions (concentration) swells with consecutive stages of discharge process, is converted into additional dispersion of a liquid phase.

The mechanism of liquid dispersion employed in a device according to invention is entirely mechanical, therefore any use of surfactants is not necessary and use of any motive gas covered in relevant regulations is allowed. Universal character of the mechanical method of dispersion tolerates use of a wide range of chemical additions soluble in liquid. Introduction of surfactants is acceptable, however this would cause that without any further modifications the presented mist fire extinguisher would be transformed into a high-performance compressed-foam fire extinguisher.

Very satisfactory results were observed during trial performance tests of an atomiser according to invention, a mist fire extinguisher filled with pressurised gas (nitrogen) and a water charge inside the reservoir was used. The reservoir volume (capacity) was 10.7 I; the charge was 6 I of water as an extinguishing agent, initial pressure in the reservoir was 5 bar. A stable mist plume having a throw distance of 11 metres falling to 8 metres was observed. Water droplet break-up was very effective; diameter sizes were below 80 micrometres on average, and for carefully executed nozzle droplet diameters did not exceed 120 micrometres. Throughput of the liquid agent attained a range of 11 l/minute. Duration of fire extinguisher full discharge was 29 seconds. For the same stored pressure, for a reservoir of 3.7 I capacity and water charge of 2 I, corresponding values were 10.5 falling to 7.5 metres, for the reach, and 12 seconds, for a full discharge. Observed performance parameters were very good, taking into account the displacement volume of accessories causing the water fill rate to reach 60%, but a high fire suppression effectiveness could be obtained even when this rate reaches 70%.

Key to drawings:

1 reservoir

2 liquid charge

3 gas under pressure

4 discharge control assembly

5 plunger tube

6 restrictor filter bushing

exit nozzle

side openings in plunger tube restrictor body

filter

threaded connection

gorge of tube

criss-crossed barriers of restrictor composite nozzle chassis front plate of composite nozzle stator plate of composite nozzle packing chamber

tip to connect hose