EP1899021A1

EP1899021A1 - Liquid mist fire extinguisher and use thereof

Info

Publication number: EP1899021A1
Application number: EP06778938A
Authority: EP
Inventors: Bouaza Mesli; Michel Lahouati
Original assignee: Eurofeu SA
Current assignee: Eurofeu SA
Priority date: 2005-07-07
Filing date: 2006-06-14
Publication date: 2008-03-19
Also published as: FR2888124B1; FR2888124A1; WO2007006987A1

Abstract

The invention concerns a liquid mist (25) fire extinguisher (1) comprising a reservoir (2) containing liquid and gas under pressure to expel the liquid outside the reservoir. The extinguisher comprises an exit member (3) having at least one outlet for dispensing the liquid outside the reservoir and a plunger tube (6) extending into the reservoir. The reservoir comprises a lower portion (4) containing the liquid when the extinguisher is in a normal operating position. The plunger tube comprises a suction opening (8) arranged in the lower portion and an inside channel (7) connecting the suction opening to the exit member. The reservoir comprises an upper portion (5) containing the pressurized gas in said normal operating position. The extinguisher comprises gas intake means (10) connecting the upper portion of the reservoir to the inside channel of the plunger tube to allow said gas to penetrate into the inside channel to be expelled outside the reservoir with the liquid.

Description

LIQUID FOG EXTINGUISHER AND USE THEREOF

The present invention relates to a liquid mist extinguisher and its use. Portable fire extinguishers intended to expel an extinguishing agent under pressure have been known since the end of the 19th century.

One type of known fire extinguisher is called water spray extinguisher. A water spray extinguisher includes a tank containing an extinguishing agent, usually water or water containing an additive. In operation, pressurized gas pushes the liquid out of the reservoir in the form of relatively large droplets.

Extinguishers of this type have several disadvantages. They do not allow to extinguish all types of fire. In general, a fire extinguisher can extinguish a fire of solid, says class A fire, and, if an additive is added to the water, a fire of liquid, said class B fire. These fire extinguishers have a reduced efficiency of so that a significant amount of water is needed, for example 6 liters for a fire extinguisher with a life of 45 to 50 seconds. Water can cause additional damage in the building where the fire is taking place, for example on the lower floors of the building where the fire takes place.

Another type of known fire extinguisher is called a water mist extinguisher. A fog extinguisher includes a tank containing extinguishing liquid, usually water or water containing an additive. During operation, a pressurized gas pushes on the liquid to expel it from the reservoir in the form of mist of droplets. We speak of fog when the droplets have an average diameter of less than 400 .mu.m.

Water mist extinguishers have several advantages over traditional fire extinguishers such as water spray extinguishers. Because of the small size of the droplets, the fog provides a larger total exchange surface for a given quantity of water than a water spray extinguisher. A water mist extinguisher is therefore more efficient and it is possible to use a reduced amount of water, which reduces the damage caused by water. Moreover, as the water mist is a dispersed phase, it is non-conductive. A water mist extinguisher can be used to extinguish a fire in an electrical installation. DE-44 43 111-A1 discloses a fire extinguisher in which water is expelled at high speed from a tank. Because of the large velocity difference between the expelled water and the ambient air, the water jet is broken up into small droplets as it enters the ambient air, i.e. Exit level of the extinguisher. To expel the water at high speed, gas at very high pressure, greater than 50 bars, is necessary.

The document Bouaza MESLI, "Experimental studies on the extinction by water mists of turbulent flames of stabilized premixes between two opposing jets", Thesis presented at the University of Orleans and defended on December 20, 2000, describes an experimental installation in which water is expelled from a tank due to pressure exerted by a gas at a pressure of about 6 bar. A water pipe connects the tank to an injector. A gas duct connects a gas source at 6 bars to the injector. The injector, which consists of an inner nozzle and an outer nozzle, mixes the gas and the water and expels the mixture. A mist of small water droplets is formed due to the difference in speed between the gas and the water.

This experimental setup has several disadvantages. Two ducts are needed to bring water and gas to the injector. The injector must have a special structure to be able to mix the water and the gas and expel the mixture in the form of water mist.

The object of the invention is to provide a liquid mist extinguisher that does not present at least some of the aforementioned drawbacks of the prior art.

For this, the invention provides a liquid mist extinguisher comprising a reservoir for containing liquid and pressurized gas able to exert pressure on said liquid so as to expel said liquid from said reservoir, said extinguisher comprising outlet having at least one outlet for dispensing said liquid outside the tank and a dip tube extending at least partially in said tank, said tank having a lower portion for containing said liquid when said extinguisher is in a normal position of use, said dip tube having a suction opening arranged in said lower portion of the tank and an inner channel connecting said suction opening to said outlet member, said tank having an upper portion for containing said pressurized gas in said normal position of use, characterized in that said extinguisher comprises gas inlet means connecting the upper portion of the reservoir with the inner channel of the dip tube to allow said gas to enter said inner channel to be expelled from said reservoir with said liquid.

Thanks to these characteristics, the fire extinguisher expels a mixture of liquid and gas so as to form a mist of small droplets. The exit velocity of the liquid does not have to be large. The pressure of the gas under pressure can therefore be limited. The structure of the extinguisher can be very simple because it is not necessary that the extinguisher includes two separate conduits, one for the gas and the other for the liquid. Similarly, an injector of particular shape to achieve a mixture between the liquid and the gas is not necessary. The extinguisher according to the invention can be easily manufactured by modifying a conventional water spray extinguisher. It has been found to be highly effective and capable of extinguishing many types of fire, including oil or animal or vegetable fires, known as Class F fire. In fact, because of the small size of droplets, the droplets evaporate before touching the oil or grease on fire, which avoids the dangerous oil spatter that is usually obtained when liquid phase water comes into contact with oil hot. Preferably, the gas inlet means comprise at least one hole formed in a wall of the plunger tube, at an upper portion of the plunger tube which extends in the upper portion of the reservoir.

In this case, the structure of the extinguisher is particularly simple. It can be designed for example by replacing the dip tube without the hole of a conventional water spray extinguisher with a dip tube having at least one hole, and filling the tank with liquid and gas in an appropriate amount.

Advantageously, the dip tube comprises a mixing portion between the gas inlet means and the outlet member, intended to achieve a mixture between the pressurized gas and the liquid.

According to a particular embodiment, the reservoir is substantially cylindrical, the dip tube being substantially rectilinear and extending in a direction parallel to the axis of the reservoir.

Preferably, in the manufacture of the fire extinguisher, the gas under pressure is introduced directly into said tank. In this case, no auxiliary gas tank is needed. The fire extinguisher is particularly lightweight and very simple structure.

Advantageously, the extinguisher contains pressurized gas and liquid in relative amounts adapted to be able to expel substantially all said liquid out of said tank.

Preferably, the suction opening, the gas inlet means and the at least one outlet orifice have passage cross sections adapted to produce a liquid mist.

Preferably, the fire extinguisher is capable of producing a liquid mist consisting of droplets with a mean diameter of less than 400 μm.

According to a particular embodiment, the output member comprises a fire extinguisher head fixed in an opening of the tank, the dip tube being fixed to the extinguisher head, the fire extinguisher head comprising an internal channel communicating with the channel. internal of the dip tube, so that the liquid and the gas pass into said internal channel of the head during the expulsion out of the tank. The extinguisher head can therefore have a very simple structure because only a single internal channel is sufficient in the head. Preferably, said output member comprises a valve adapted to close said internal channel of the extinguisher head and a control member of said valve.

According to a particular embodiment, said extinguisher head comprises a fixing sleeve for fixing a cartridge pressurized gas, and a pressurizing member adapted to open a communication between said cartridge and said reservoir. Thus, the life of the fire extinguisher is improved because the cartridge can have a very good seal before the actuation of the pressurizing member. Preferably, said fixing sleeve is arranged to fix said cartridge in said reservoir. Thus, the size of the fire extinguisher is reduced.

According to a particular embodiment, said output member comprises a diffuser provided with said at least one outlet orifice and connected to said extinguisher head so that said at least one outlet orifice communicates with said inner channel of the head of extinguisher.

Preferably, said output member comprises a lance connecting said diffuser to said extinguisher head.

Many types of diffusers are suitable for producing such an extinguisher, for example with a single outlet or with several outlets. The shape of the outlet or openings may be circular, square, elongated or otherwise. Advantageously, said diffuser has a spherical cap-shaped wall and a plurality of outlet orifices distributed on said wall. According to a particular embodiment, the fire extinguisher is autonomous and portable. The fire extinguisher can also be realized in the form of a fixed installation. According to a particular embodiment, said output member comprises a fixed pipe extending between said tank and a room to be protected and a diffuser connected to said pipe and arranged in said room to be protected.

The invention also provides a use of a fire extinguisher according to the invention above for extinguishing a solid fire, a flammable liquid fire including vegetable or animal oil or fat or a gas fire. Preferably, said fire is a fire of oil or vegetable or animal fat.

The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent in the following description of several embodiments. particular of the invention, given solely for illustrative and non-limiting, with reference to the accompanying drawings. On these drawings:

- Figure 1 is a sectional view of a fire extinguisher according to a first embodiment of the invention;

FIG. 2 represents the plunger tube of the fire extinguisher of FIG. 1;

FIG. 3 is a sectional view of the extinguisher head of the extinguisher of FIG. 1; - Figure 4 is a front view of the head of Figure 3, in partial section;

FIG. 5 is a sectional view of a diffuser that can be used in the fire extinguisher of FIG. - Figure 6 is a left view of the diffuser of Figure 5;

- Figure 7 is a sectional view of a fire extinguisher according to a second embodiment of the invention; and FIG. 8 is a sectional view of the extinguisher of FIG. 7, along the section line VIII - VIII of FIG. 7.

The portable fire extinguisher 1 comprises a substantially cylindrical tank 2 of circular section. Figure 1 shows the fire extinguisher 1 arranged in its normal position of use, with the axis of the tank 2 extending vertically. A fire extinguisher head 3 is fixed in an opening in the wall of the tank 2, at the top of the tank 2.

The tank 2 contains water and gas under pressure. The gas may be, for example, air, nitrogen or carbon dioxide.

When the fire extinguisher is in its normal position of use, the water occupies, by gravity, a lower portion 4 of the tank 2, and the gas occupies an upper portion 5 of the tank 2.

A cylindrical dip tube 6, of circular section, extends into the tank 2. In the example shown, the dip tube is coaxial with the tank 2. The dip tube 6 comprises a channel 7 opening inside the reservoir 2 at a suction opening 8, located at the lower end of the plunger tube 6 arranged in the lower portion of the reservoir 2. Thus, when the fire extinguisher is in its normal position of use, the suction opening is immersed in water and allows the water to enter the channel 7.

The plunger tube 6 is fixed, by its upper end 9, to the extinguisher head 3, for example by screwing or fitting.

The plunger tube 6 has an upper portion which extends in the upper portion 5 of the reservoir 2. In the vicinity of the head 3, in the upper portion of the tube 6, the tube 6 has one or more lateral holes

10, for example four lateral holes 10 distributed on the periphery of the tube 6, and only one of which is shown in FIGS. 1 and 2. The holes 10 pass through the wall of the dip tube 6. When the fire extinguisher is in its normal position, the holes 10 are not immersed in the water. Thus, they allow the gas to enter the inner channel 7 of the dip tube 6. Of course, the dip tube 6 could have more or fewer than four lateral holes. For example, the dip tube could have a single side hole.

The extinguisher head 3 is shown in greater detail in FIGS. 3 and 4. The head 3 comprises a body 11 fixed to the reservoir 2. An internal channel 12 that is substantially L-shaped is formed in the body

11. The internal channel 12 has an inlet portion 13 in communication with the internal channel 7 of the plunger tube 6. The internal channel 12 also has an outlet portion 14 opening outwardly of the reservoir 2 transversely to the axis of the tank 2 and forming diffuser. The inner channel 12 has a reduced section portion 15 forming frustoconical valve seat. A valve 16 is movably arranged in the channel 12. A spring 17, bearing on a shoulder of the channel 12 and on the valve 16, biases the valve 16 in a closed position, shown in FIG. 3, in which the valve 16 cooperates with the valve seat to close the channel 12. A piston 18 is movably arranged in the body 11. The piston 18 is fixed to the valve 16 and is able to move the valve 16, against the spring 17, in an open position in which the valve 16 does not cooperate with the valve seat and does not close the channel 12. The displacement of the piston 18 is controlled by a control handle 19. For this, the Fire extinguisher head 3 carries a fixed handle 60 extending in the same transverse direction as the control handle 19 and against which the handle 19 can be folded down to open the valve. A pin 20 is provided to block the operation of the handle 19 and thereby prevent the valve 16 from being moved to its accidentally open position. The extinguisher head 3 also comprises a safety member 21, shown in section in FIG. 4 and which will not be described in more detail because it is a conventional pressure relief valve.

The operation of extinguisher 1 according to Figure 1 is as follows. Fire extinguisher 1 is kept near a place to be protected. The pin 20 blocks the operation of the handle 19. The valve 16 closes the channel 12. Thus, the pressurized gas and the water are held in the tank 2.

In case of fire, for example in the case where the oil of a restaurant fryer ignites, a user enters the fire extinguisher 1 and removes the pin 20. He orients the fire extinguisher 1 so as to direct the portion of the fire extinguisher. exit 14 from the head 3 towards the fire. Then it actuates the handle 19. The piston 18 slides in the body 11 and the valve 16 is found in its open position. In this case, the channel 7 of the dip tube 6 and the channel 12 of the head 3 form a passage between the inside and the outside of the tank 2, allowing the flow of water and gas. The pressurized gas exerts pressure on the water. This pressure causes the water to enter the internal channel 7, at the suction opening 8, as represented by the arrows 22, and to flow the water in the channel 7, as represented by the arrows 23, to the outside of the tank 2. The gas also enters the internal channel 7, through the holes 10, as shown by the arrows 24. In the inner channel 7 of the dip tube 6, downstream of the holes 10, the gas and the water mix and flow out of the tank 2, through the inner channel 12 of the head 3 while forming a mist of small water droplets, due to the difference in speed between the water and the gas. At the outlet of the internal channel 12, the mixture of water and gas is expelled from the tank 2 in the form of a mist jet 25. The mist jet 25 has for example a range of 8 to 10 m. By dimensioning the extinguisher 1 appropriately, it is possible to obtain a water mist 25 whose droplets have a desired average diameter less than 400 microns. Different parameters influence the size of the droplets, such as the diameter d1 of the outlet portion 14 of the channel 12, the number and the diameter d2 of the lateral holes 10, the net volume V of the tank 2, the pressure Ps of the gas under pressure, the amount of water Q, and the diameter d3 of the suction opening 8 of the dip tube 6. Example

For example, with a portion 14 of diameter d1 = 4mm, four holes 10 of diameter d2 = 2.1mm, nitrogen at pressure Ps = 15 bar (at a temperature of about 20 ⁰ C), a reservoir 2 of volume V = 10 liters, 3 liters of water and an opening 8 of diameter d3 = 12 mm, extinguisher 1 provides a water mist whose droplets have an average diameter of less than 400 microns. A mist of water with a range of 8 m is obtained for 25 seconds. When sizing the fire extinguisher 1, it is necessary to provide that the diameter d2 of the lateral hole or holes 10 must be small enough to avoid defusing the flow of water. In other words, in absolute value, the pressure drop generated by the lateral hole during the flow of gas in the lateral hole must be greater than the pressure drop due to the weight of the water column between the level of the liquid surface and the level of the lateral hole.

Because of the small size of the droplets, the fire extinguisher 1 therefore has a high efficiency. In the case where the pressurized gas is nitrogen or carbon dioxide, the efficiency of extinguisher 1 is further improved by the "choking" effect of these gases.

Of course, the outlet portion 14, the lateral holes 10 and the opening 8 are not necessarily of circular section and in this case, instead of their respective diameters, the dimensioning parameters to be taken into account are their cross sections. respective passage.

In a variant, the fog is not formed directly at the outlet of the head 3, but at a diffuser connected to the head 3 by a lance. This allows the fog to be easily directed to the fire by placing the diffuser appropriately. In this case, the diameter of the outlet orifice of the diffuser must also be dimensioned appropriately. In another variant, the fire extinguisher 1 is not portable, on the contrary it is fixed. It comprises one (or more) diffuser fixed in a room to be protected so as to be able to direct the water mist towards a device to be protected, for example an electrical cabinet, a boiler room, etc. The diffuser is connected to the extinguisher head 3 by a fixed pipe. For example, several diffusers can be connected to the same channel.

An example of a diffuser that can be used, for example in the case of the fixed extinguisher 1, is shown in FIGS. 5 and 6. The spherical diffuser 30 has a liquid inlet channel 31, and a diffusion wall 32 spherical cap shape defining an interior space 34 in communication with the inlet channel 31. The diffusion wall 32 has a plurality of outlet orifices 33. Thus, if a mixture of water and pressurized gas is brought into space 34 through the channel 31, this mixture will be expelled in different directions corresponding to the different orientations of the orifices 33. The diffuser 30 thus makes it possible to create a jet of water mist very open and occupying a large volume around the diffuser 30.

Other liquids than water may be used in extinguisher 1. For example, the liquid may be water comprising an additive known by the acronym AFFF (Floating Film Forming Agent). It has been found that through the use of an AFFF type additive, the effectiveness of extinguisher 1 is improved even by using a smaller additive concentration compared to a water spray extinguisher.

Figures 7 and 8 show a portable fire extinguisher 1 according to a second embodiment of the invention. Elements identical or similar to elements of the first embodiment bear the same references and will not be described in detail. The extinguisher 1 according to the second embodiment is called auxiliary pressure extinguisher.

The extinguisher head 3 comprises a fixing sleeve 45 for fixing a cartridge 46 of gas under pressure in the tank 2. The cartridge 46 has a head 47 fixed to the sleeve 45, for example by screwing or fitting. The cartridge 46 is made of a relatively solid material, except at a lid (not shown) arranged at the head 47. The extinguisher head 3 comprises a striker 48 movably arranged and controlled by a handle 53 which acts as a percussion and portage. A pin 49 makes it possible to fix the striker 48 at a distance from the lid of the cartridge 46. The head 3 has a communication channel 52, starting from the sleeve 45 and opening into the tank 2.

The fire extinguisher head comprises an outlet tube 50 defining a substantially L-shaped channel 42. A stop valve 51 shown schematically makes it possible to close the channel 42. The channel 42 has an input portion in communication with the channel 42. internal channel 7 of the plunger tube 6, and an outlet potion 44 opening out of the tank 2.

The operation of the fire extinguisher 1 with auxiliary pressure is as follows. Fire extinguisher 1 is kept near a place to be protected. The pin 49 holds the firing pin 48 in position and the cartridge 46 is closed and contains gas under pressure. The gas in the upper portion 5 of the tank 2 is substantially at atmospheric pressure. The stopcock 51 closes the channel 42. Thus, the water is maintained in the reservoir 2.

In the event of a fire, a user grasps the extinguisher 1 and removes the pin 49. He hits the cartridge 46 by raising the handle 53. The striker 48 resting on the handle 53 moves towards the lid of the cartridge 46 and the piercing. Another mode of operation of the known percussion handle is the percussion by lowering the handle. The pressurized gas exits the cartridge 48, passes through the channel 52 and fills the upper portion 5 of the tank 2. The user orients the fire extinguisher 1 so as to direct the output portion 44 of the head 3 towards the fire. Then it operates the stopcock 51 to open the channel 42.

In this case, the channel 7 of the dip tube 6 and the channel 42 of the head 3 form a passage between the inside and the outside of the tank 2, allowing the flow of water and gas. The following operation is similar to that of the extinguisher according to the first embodiment. At the outlet of the internal channel 42, a mixture of water and gas is expelled from the tank 2 and forms a mist of small water droplets, due to the difference in speed between the water and the gas. With respect to the fire extinguisher 1 according to the first embodiment, wherein the valve formed by the valve 16 and the valve seat may have a low leakage rate limiting the passive life of the fire extinguisher, the extinguisher according to the second embodiment has the advantage that the pressurized gas is contained in a perfectly sealed cartridge. Thus, the passive life of the extinguisher according to the second embodiment is greater.

Although the invention has been described in connection with several particular embodiments, it is obvious that it is not limited thereto and that it comprises all the technical equivalents of the means described and their combinations if they are within the scope of the invention.

Claims

A liquid mist extinguisher (1) (25) comprising a reservoir (2) for containing liquid and pressurized gas adapted to exert pressure on said liquid so as to expel said liquid from said reservoir, said extinguisher comprising an outlet member (3, 30) having at least one outlet (14, 33, 44) for dispensing said liquid to the outside of the tank and a dip tube (6) extending at least partially into said tank, said tank having a lower portion (4) for containing said liquid when said fire extinguisher is in a normal use position, said dip tube having a suction opening (8) arranged in said lower portion of the tank and an inner channel ( 7) connecting said suction opening to said outlet member, said tank having a top portion (5) for containing said pressurized gas in said normal position of use, characterized characterized in that said extinguisher comprises gas inlet means (10) connecting the upper portion of the reservoir with the inner channel of the dip tube to allow said gas to enter said inner channel to be expelled from said reservoir with said liquid, said suction opening, said gas inlet means and said at least one outlet having passage cross sections adapted to produce a liquid mist.

2. Fire extinguisher according to claim 1, characterized in that said gas inlet means comprise at least one hole (10) formed in a wall of the plunger tube, at an upper portion of the plunger tube which extends in said upper portion of the tank.

3. Fire extinguisher according to claim 1 or claim 2, characterized in that said dip tube comprises a mixing portion between said gas inlet means and said outlet member, intended to achieve a mixture between said gas under pressure and said liquid.

4. Fire extinguisher according to one of claims 1 to 3, characterized in that said reservoir is substantially cylindrical, said dip tube being substantially rectilinear and extending in a direction parallel to the axis of said reservoir.

5. Fire extinguisher according to one of claims 1 to 4, characterized in that in its manufacture, said pressurized gas is introduced directly into said tank.

6. Fire extinguisher according to one of claims 1 to 5, characterized in that it contains pressurized gas and liquid in relative amounts adapted to be able to expel substantially all said liquid out of said tank.

7. Fire extinguisher according to one of claims 1 to 6, characterized in that it is capable of producing a liquid mist consisting of droplets with an average diameter of less than 400 microns.

8. Fire extinguisher according to one of claims 1 to 7, characterized in that said output member comprises a fire extinguisher head (3) fixed in an opening of said reservoir, said dip tube being fixed to said extinguisher head, said extinguisher head comprising an inner channel (12, 42) communicating with said inner channel of said dip tube, whereby said liquid and said gas pass into said inner channel of the head upon expulsion from said reservoir.

9. Fire extinguisher according to claim 8, characterized in that said output member comprises a valve (15, 16; 51) adapted to close said internal channel of the extinguisher head and a control member (19; said valve.

10. Fire extinguisher according to claim 8 or claim 9, characterized in that said extinguisher head comprises a fixing sleeve (45) for fixing a cartridge (46) of gas under pressure, and a pressurizing member ( 48, 49, 53) adapted to open a communication between said cartridge and said reservoir.

11. Fire extinguisher according to claim 10, characterized in that said fixing sleeve is arranged to fix said cartridge in said reservoir.

12. Fire extinguisher according to one of claims 8 to 11, characterized in that said output member comprises a diffuser provided with said at least one outlet orifice and connected to said extinguisher head so that said at least one orifice of outlet communicates with said inner channel of the extinguisher head.

13. Fire extinguisher according to claim 12, characterized in that said output member comprises a lance connecting said diffuser to said extinguisher head.

14. Fire extinguisher according to claim 12 or claim 13, characterized in that said diffuser (30) has a wall (32) shaped spherical cap and a plurality of outlet orifices (33) distributed on said wall.

15. Fire extinguisher according to one of claims 1 to 14, characterized in that it is autonomous and portable.

16. Fire extinguisher according to one of claims 1 to 14, characterized in that said output member comprises a fixed pipe extending between said tank and a room to be protected and a diffuser connected to said pipe and arranged in said room to protect.

17. Use of a fire extinguisher according to one of claims 1 to 16 to extinguish a solid fire, a fire of flammable liquid including oil or vegetable or animal fat or gas fire.

18. Use according to claim 17, characterized in that said fire is a fire of oil or vegetable or animal fat.