US3602312A

US3602312A - Process for quenching flames and extinguishing fires and devices therefor

Info

Publication number: US3602312A
Application number: US841460A
Authority: US
Inventors: Nicolino Rainaldi; Pierluigi Fatutto
Original assignee: Montedison SpA
Current assignee: Montedison SpA
Priority date: 1968-07-15
Filing date: 1969-07-14
Publication date: 1971-08-31
Anticipated expiration: 1988-08-31
Also published as: SE364445B; GB1236909A; ES369495A1; NL6910479A; DE1935269A1; FR2014607A1; NO127846B; BE736110A; DE6927485U; CH501434A

Abstract

A process for quenching flames which involves directing thereat symmetrical dibromotetrafluoroethane (BrF2C-CF2Br, 1,1,2,2tetrafluoro-1,2-dibromoethane) through a nozzle having a chamber traversed by this compound prior to emission from the orifice thereof which frustoconically converges in the direction of the orifice with half angle (conicity angle) of the cone ranging from 4* to about 20*, preferably between 5* and 18*. Preferably the outlet orifice at the exit of the chamber is elliptical with a ratio between the major half axis and the minor half axis between 5 and 1, preferably between 2.5 and 1.25, while the inlet orifice is circular and the transition from inlet orifice to outlet orifice is continuous. The dibromotetrafluoroethane is projected as a jet from this chamber at a pressure between 4 and 20 atm.

Description

169-4-7. OR 396029312. SR

7 i I "M 3,602,312

[72] Inventors Nicolino Rainaldi 2,959,359 11/1960 Casaletto 239/601 X Mestre; 3,343,794 9/1967 Voitsekhovsky 239/601 X Pierluigi Fatutto, Venezia. both of, Italy FOREIGN P [21] Appl. No. 841,460 9 l [22] Filed July 14 1969 589,990 1/1960 Canada OTHER REFERENCES {45] Patented Aug.31,l971 v Herzka and Pickthall PRESSURIZED PACKAGING [73} Assignee MontecatiniEdisonS.p.A.

Milan, Italy (AEROSOLS). London, Butterworths Scientific Publica- [32] Priority July 15, 1968, Apr. 24, 1969 tions. 1958. Chapter 111. page 76. QD 549 H47. Copy in [33] Italy group 220. [3] l8982A/68 and MONA/69 Primary Examiner-M. Henson Wood, Jr.

Assistant Examiner-Edwin D. Grant A!!0rneyl(arl F. Ross [54] PROCESS FOR QUENCHING FLAMES AND EXTINGUISHING FIRES AND DEVICES ABSTRACT: A process for quenchlng flames whlch involves THEREFOR I 17Claims6Drawing Figs directing thereat symmetrical dlbromotetrafluoroethane (BrF c-CF Br, 1,1,2,2-tetrafluoro-1,2-dibromoethane) [52] U.S.Cl 169/1 through a nozzle having a Chamber traversed by i [511 A62c pound prior to emission from the orifice thereof which [50] Field of Search i 169M 1 frustoconically converges in the direction of the orifice with l Bing/601 half angle (conicity angle) of the cone ranging from 4 to about 20, preferably between 5 and 18. Preferably the out- [561 References cied let orifice at the exit of the chamber is elliptical with a ratio UNITED STATES PATENTS between the major half axis and the minor half axis between 5 587,532 8/1897 Morgan 169/31 and 1, preferably between 2.5 and 125, while the inlet orifice 1,768,700 7/1930 MacGregor 169/31 is circular and the transition from inlet orifice to outlet orifice 2,021,981 11/1935 Bichowsky 169/1 A is continuous. The dibromotetrafluoroethane is projected as a 2,653,130 9/1953 Eiseman 169/1 jet from this chamber at a pressure between 4 and 20 atm.

BrF C 0 E281 ATENTEU M1831 I97;

sum 1 or 2 INVIL'N'I'O/(S:

NICOLINO RAINALDI BY PIERLUIGI F UTTO ATTORNEY ATENTED AUBBI I971 SHEET 2 OF 2 FIG.3

BrF C-CE Br INVENTORS:

NICOLINO RAINALDI y PIERLUIGI FATUTTO FIG.4

ATTORNEY PROCESS FOR QUENCI-IING FLAMES AND EXTINGUISHING FIRES AND DEVICES THEREFOR SPECIFICATION Our present invention relates to a method of quenching fires and extinguishing flames using as the extinguishing compound dibromotetrafluoroethane and to a device for carrying out this method.

The highly efi'rcient flame-quenching and fire-extinguishing properties of symmetricaldibromotetrafluoroethane (BrF C- CF Br) have beendescribed in our copending application Ser. No. 827,959, filed May 26, 1969. It has been pointed out prior to our discoveries that various substances have greater capacity than others as flame-extinguishing materials and may be used to advantage in fire extinguishing of the canister or tank type. For the purposes of the present application, a fire extinguisher of the canister type will be one which has a self-contained pressure source, e.g.- a liquid propellant, a pressurized gas propellant or the like, from which the flame-extinguishing compound is driven in the form of a jet through a hose, pipe, tube or outlet orifice. Tank-type extinguishers within the meaning of the present application, are those which may be mounted on wheels or may constitute part of a vehicle structure and may be provided with a self-contained pressure source, but also may consist of a reservoir for the fire-extinguishing compound or composition which is driven through the outlet orifice, e.g. at the end of a hose more readily manipulatable by the user than an entire canister or as part of a permanent installation, by a pump or other driving means independent of the reservoir.

As indicated earlier, sym-dibormotetrafluoroethane has been found to have peculiarly advantageous properties as a flame extinguishing substance since it apparently is not readily dispelled from the combustion site, absorbs surprisingly large quantities of heat and also form an oxygen-excluding blanket about the combustion site. For the most part, prior attention to fire-extinguishing compounds have concentrated upon finding substances with optimum characteristics, either as a heatdissipating or cooling agent at the site of combustion or as an oxygen-blocking noncombustible material capable of reducing the availability of combustion-supporting air. Most surprisingly, both properties are combined in dibromotetrafluoroethane, which has even been found to have vastly superior flame-extinguishing properties by comparison with its homologues and members of the halogenatedhydrocarbon family.

Further investigations have, however, shown that the use of dibromotetrafluoroethane as a flame-quenching, fire-extinguishing substance has certain drawbacks and is less than fully satisfactory, because of the relatively large quantity of the material required to extinguish a fire and the time required for such extinction.

It is, therefore, the principal object of the present invention to provide an improved method of extinguishing fires and quenching the flames of fires wherein the aforementioned disadvantages are obviated.

Another object of this invention is to provide an improvedmethod of extinguishing fires with dibromotetrafluoroethane and thereby extending the principles set forth in our copending application Ser. No. 827,959, mentioned earlier.

It is further an object of this invention to provide a method of extinguishing fire in a combustible liquid, characterized by its spread over large surfaces, in an economical fashion, both with respect to the quantity of the extinguishing compound used per unit area of the combustion site and with respect to the time required for total quenching of the fire.

Another object of the instant invention is to provide an improved device or system for carrying out the method of the present invention and for extinguishing fires and quenching flames with sym-dibromotetrafluoroethane in much shorter times than has been possible heretofore and with a minimum quantity of this flame-quenching agent.

Still another object of the present invention is to eliminate or reduce the above-described drawbacks, thereby obtaining a quenching of the flame'in short order, even on burning surfaces of considerable spread and with a limited consumption of the fire-extinguishing product.

It is yet another object of our invention to provide a process for extinguishing fires which is applicable both to mobile fireextinguishing apparatus, such as portable fire extinguishers or wheel-mounted fire extinguishers, and to fixed fire-extinguishing equipment installed near tanks containing liquid combustibles or near machinery, in the fire-extinguishing installations of industrial, especially chemical, plants.

We have found, most surprisingly, that these objects and others which will become apparent hereinafter are attainable in a process for quenching flames and extinguishing fires which involves the step of directing at a combustion site a jet, stream or spray of symmetrical dibromotetrafluoroethane (BrF C-CF Br) through a nozzle which, immediately behind the discharge orifice and through' which the dibromotetrafluoroethane is ejected, is formed with a frustoconical chamber with a half angle a (conicity angle) of the corresponding cone ranging between 4 and about 20 and preferably between 5 and 18, the chamber converging toward the outlet orifice. I

The present discovery is indeed surprising in view of the fact that efforts in the art have heretofore concentrated upon the widespread dissemination of the fire-extinguishing substance in such manner as to obtain the broadest possible spread of the discharge from the nozzle through which the composition is ejected. Hence, efforts along these lines have concentrated on the use of aerosol sprays, divergent nozzles or nozzles having chambers diverging toward their mouth or discharge orifice.

According to a further feature of the invention the dibromotetrafluoroethane is discharged, ejected or sprayed from a nozzle whose discharge orifice, which has a cross-sectional area (flow across section) less than the cross-sectional area or flow cross section of the inlet orifice of the frustoconical converging chamber, is of somewhat elliptical configuration with a ratio of the major half axis to the minor half axis of the ellipse ranging between 5 and 1 (5:1 to 1:1) and preferably between 2.5 and 1.25 '(2.5:1 to 1.25:1). In this case, the surface of the frustocone converges smoothly and continuously toward the elliptical orifice from the circular orifice and provides a continuous frustoconical transition therebetween. Of course, the present invention also contemplates the use of chambers conforming to a frustum of a right circular cone.

Still another feature of this invention resides in the step of discharging the dibromotetrafluoroethane from the nozzle at a pressure between 4 and 20 atm., i.e. the driving pressure behind the dibromotetrafluoroethane is 4-20 atm. and preferably between 6 and 16 atm. As previously noted, the driving force may derive frompressurization of a reservoir containing the dibromotetrafluoroethane, e.g. a propellant having a high-vapor pressure and constituting a vapor at operating temperatures. The propellant may be a pressurizing gas which may have flame-quenching properties itself or may be inert with respect to the flame-quenching action, and preferably is not combustion sustaining, or gases designed to drive the dibromotetrafluoroethane through the nozzle without mixing or miscible therewith. Furthermore, propellants need not be used, but pumps or the like may be employed to displace the dibromotetrafluoroethane at the described pressure.

We have found that this method of extinguishing fires using dibromotetrafluoroethane is highly suitable for the quenching of flames rising from combustible liquids spread over relatively wide areas, e.g. flammable gasoline, oil, solvents and the like spread on water, ship and dock structures, areas surrounding tank farms, chemical plant equipment, etc. However, the extinguishing process may be used effectively also materials as well.

Still another aspect of 'the invention resides in the apparatus or device for carrying out the aforementioned method and, therefore, the means for combatting fires, extinguishing flames, etc. With dibromotetrafluoroethane, according to this aspect of the invention, a nozzle is provided ahead of a source of dibromotetrafluoroethane under pressure, the nozzle having a discharge orifice fed by a frustoconical chamber converging in the direction orifice fed by a frustoconical chamber converging in the direction of this orifice with a conicity angle a or half angle of the corresponding cone which lies between 4 and 20 but preferably is between and 18. This chamber, which has the circular inlet orifice mentioned earlier, may have a circular discharge orifice or an elliptical discharge orifice, also as mentioned above. The section of the outlet orifice conforms preferably to the minor base of the frustocone.

The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is an axial cross-sectional view, partly in diagrammatic form, of a nozzle for use in the present method;

FIG. 2 is an end view taken in the direction of the discharge.

orifice of FIG. 1;

FIG. 3 is a view similar to FIG. 1 of another embodiment of a nozzle according to the present invention with the section being taken in the plane of the minor axis of the elliptical discharge orifice;

FIG. 4 is an end view of the nozzle seen in the direction of the discharge orifice;

FIG. 5 is a cross-sectional view taken generally along the lines V+V of FIG. 3; and

FIG. 6 is a somewhat diagrammatic view, in elevation, of an apparatus using the nozzle of FIGS. 1 and 2 or FIGS. 3-5.

In FIGS. 1 and 2 I show a nozzle N to which symdibromotetrailuoroethane is fed as represented by arrow D for directing a jet of the dibromotetrafluoroethane onto the site of combustion as a fire-extinguishing and flame-quenching composition.

This nozzle has a circular base 2 at one end of his body which may be affixed to a nozzle of dibromotetrafluoroethane under pressure, e.g. by means of a threaded coupling, along the inner wall of'a cylinder bore 2' formed in this portion of the nozzle body.

The forward end of the nozzle body converges frustoconically in the direction of discharge of the dibromotetrafluoroethane and is provided with a chamber 3 axially extending within the body and terminating in a discharge orifice 4 of circular configuration at the front end of the nozzle body. The nozzle 4 is of smaller cross section than the inlet orifice 5 of the chamber 3 at which the dibromotetrafluoroethane is admitted into this chamber. The noule may be fitted onto a vessel, container or any conventional source of a pressurized liquid, such as a cylinder or bottle containing dibromotetrafiuoroethane and a propellant as described in the aforementioned copending application and described above, The chamber 3 has a frustoconical configuration conforming to a frustum of a right circular cone with an apex angle in the longitudinal section ABC between about 4 and about 20.

The flame-quenching, fire-extinguishing composition is ejected through the nozzle 1 in the direction represented by arrow D and flows from the orifice 4, the cross section of which coincides with the minor base of the frustocone 3 and with a truncating plane through the imaginary cone of apex angle 2a or conicity angle (half angle) a and the axis CE, with a generatrix AC.

As noted earlier, the shape of the orifice 4 may vary depending upon the specific requirements. Thus the discharge orifice 4 may be of circular configuration (FIGS. 1 and 2) or, preferably, of elliptical configuration (FIGS. 3-5) as shown for the orifice 4' of the nozzle N. Other configurations of discharge orifice have also been found to be satisfactory, although the elliptical shape has proved to be the most effechydrocarbons tive inasmuch as it permits coverage of wider areas by comparison with circular discharge orifices for equal quantities of product discharged. As a practical manner, the elliptical orifice has been shown to be more efficient in disseminating the product emerging from the nozzle.

In the embodiment illustrated in FIGS. 3-5, the frustoconicaI chamber 3' has a minor base corresponding to the orifice 4' of elliptical configuration while the major base 5 is represented by the inlet orifice to the chamber 3' is a continuous transition between the circular cross section of the inlet orifice 5' to the elliptical configuration of the discharge orifice 4' so that the immediate cross sections gradually and progressively transform from the one geometrical shape to the other.

The conicity of such a chamber can be defined by two values of the half angle a of the cone. Thus one may define a half angle a corresponding to half the apex angle of the cone in the plane ABC (FIG. 5) and an angle a" corresponding to the half angle of the cone in the plane ABC orthogonal to the plane ABC. The two planes ABC and ABC correspond to planes through the minor axis a-a and the major axis bb of the nozzle as shown in FIG. 4. The angles a and a, for a system having an elliptical discharge orifice will be hereinafter referred to as the angles of major conicity (a) and minor conicity (a") whereas the half angle a for systems constituting frustums of right circular cones will be referred to simply as the conicity angle. In all cases the conicity angle is to range between 4 and 20 and preferably between 5 and 18. The ratio between the major half axis and the minor half axis of the ellipse is comprised between 5 and 1 and preferably between 2.5 and 1.25. It is evident, ofcourse, that a ratio of 1 (1:1 corresponds to a right circular cone frustum.

The actual cross-sectional area of the discharge orifice, the dimensions of the

chamber

3 or 3 and the area of inlet orifice 5, 5' will be selected in accordance with the flow rate of the dibromotetrafluoroethane desired. The extinguishing compound is used at the ambient temperature required for the extinction of the fire and may depend upon the season and location of use. In general, temperatures ofl0 C. to +40 C. will prevail at the discharge orifice. While the dibromotetrafluoroethane may be sprayed under a pressure that will vary according to the requirements, e.g. as determined by the desired flow rate and nozzle temperature, it has been found that best results are obtained in terms of fire extinguishing action, with a pressure between 4 and 20 atm. and preferably 6 and 16 atm.

As noted earlier, this pressure may be obtained by means of a mechanical device, for example, a pump, or by a propellant which may be soluble or insoluble in dibromotetrafiuoroethane. Suitable insoluble propellants include nitrogen, helium, air or other pressurized inert gas, also the use of air is possible only when the air lies above the body of the liquid in the container and the latter is driven to the nozzle via a duct leading below the compressed air. Partially soluble propellant gases, such as carbon dioxide may be used. As described in the aforementioned copending application, the propellant may even be soluble in the dibromotetrafluoroethane and, for this purpose, halogenated and preferably fluorinated and/or chlorofluorinated or bromofluorinated methanes are used. Best results are obtained with difluorodichloromethane, difluoromonochloromethane, trifluorobromomethane and tetrafluoromethane individually or in mixtures of two or more; preference is, however, given to insoluble propellants for the purposes of the present invention.

The surprisingly high efficiency of the flame-quenching activity of dibrometetrafluoroethane, used in accordance with the present invention, can be seen from the time required to extinguish a particular fire and the consumption of this compound to completely quenching of the flame. It cannot be explained by any known theory, to our knowledge, but we believe, without intending to be limited by this hypothesis that it is a consequence of the fact that, with a nozzle constructed as described and at the indicated pressures, the

dibromotetrafluoroethane is not nebulized or atomized into particles in the size range of microns as is the case with aerosol sprays, nor does the dibromotetrafluoroethane form excessively large particles. e.g. upwards of5 mm. It appears that the nozzle results in the formation of a particle size between 0.5 and 3 mm. and that this particle size range has-the surprising effect of increasing the fire-extinguishing capabilities of this particular compound. In extending these hypotheses further, we may visualize the nebulization or dispersion in a particle size range of the order of microns to promote mechanical dispelling from the site of combustion and permitting rapid evaporation prior to entry of the particles into the combustion zone in which the particles may function to absorb. Furthermore it appears that nebulization may induce air toward the combustion site and promote combustion at least to a certain extent. Particles of a larger size than those produced in accordance with the present invention appear to pass through the flame and again remain out of the flame site so as to be incapable of withdrawing heat therefrom by evaporation.

ln FIG. 6 we show an installation wherein the nozzle N or N is mounted on a valve structure V connected by a hose H to a tank T containing the BrF C-CF Br and charged with a propellant gas at G. A gauge G indicates the pressure. When no propellant gas is employed, a pump P serves to drive the flameextinguishing substance.

EXAMPLE 1 A portable fire extinguisher of 6 l. holding capacity was loaded with 6.5 kg. of symmetrical dibromotetrafluoroethane and was then pressurized at room temperature (about C.) with nitrogen, the extinguisher being equipped to ensure the constant operating pressure required during the spraying of the extinguishing product (i.e. 8 atm.).

The extinguishing test was carried out in a 1.5 m? (flame area) tank containing about 100 liters of water and 20 liters of a gasoline/gas-oil mixture in a weight ratio of 1:1.

The extinguisher was introduced after 30 seconds of combustion (this time will hereinafter be always indicated as precombustion time). The fire was extinguished within a second with a consumption in extinguishing compound 0 about l kg.

The nozzle used with the fire extinguisher was of the type represented at FIG. 1 with an orifice of circular shape and a conicity 0r=8; the orifice area was of 16 mm EXAMPLE 2 Into the 100-liter tank of a wheeled extinguisher was charged 180 kg. of C F Br and it was then pressurized as in Example 1.

The test was carried out in a 1.5 m. tank containing about 100 liters of water and 20 liters ofa gasoline/gas-oil mixture in a weight ratio of 1:1. The extinguisher was introduced after a precombustion time of 30 sec. and the fire was extinguished within 1 sec. with a consumption of extinguishing compound of about 1 kg.

The nozzle used with the fire extinguisher was of the type represented in FIG. 3 having an orifice of elliptical shape and with a conicity a'=8, a"=6. the orifice flow cross section amounting to 20 mm. and the ratio of the major half axis (d) to the minor halfaxis (d") was 3:2.

EXAMPLE 3' The same test as that of Example 2 was repeated following i EXAMPLE 4 The test of Example 3 was repeated following the same procedures and using the same equipment.

With a precombustion time of 60 seconds the extinguishing time amounted to 3 seconds with a consumption in extinguishing compound of 2.8 kg.

EXAMPLE 5 A portable fire extinguisher of 6-1iter capacity was loaded with 6.5 kg. of C F Br and was then pressurized at room temperature (about 20 C.) with nitrogen to a pressure of. l 6 atm.

Thereupon three successive tests were carried out as follows: suring the spraying of the extinguishing product the pressure decreased, owing to the discharge to a pressure of (a) 13 atm. at the end of the first test; (b) of 10 atm. at the end of the second test; and (c) of 7 atm. at the end of the third test. The extinguishing tests were carried out in a tank of 1.5 m? combustion area containing about liters of water and 20 liters of a gasoline/gas-oil mixture in a ratio of 1:1.

With a precombustion time of 30 see. the extinguishing time obtained was between 1 and 2 sec. for each test. The total consumption of extinguishing product amounted to 5 kg.

The nozzle used on the fire extinguisher was of the type represented in FIG. 3 and had an elliptical shaped orifice'and the conicity a=8 and a"=6; the orifice surface was 20 mm. while the major half axis; minor half axis ratio was equal to 3:2.

We also carried out extinguishing tests on fires from combustible substances as for instance of hydrocarbons, alcohols,

ketones, carbon sulfide, etc. in the absence of water in the EXAMPLE 6 The equipment used was the same as that described in Example 2 and the same procedure was followed, carrying out the test in a 1.5 m? (combustion area) tank containing about 10 liters of carbon sulfide With a precombustion time of 30 seconds the fire was extinguished in 1 sec. with a consumption of extinguishing compound of 0.5 kg. Further extinguishing tests were carried out whose results, for illustrative purpose, are recorded in the Tables on the following page.

"iiif e Tables: n I I Time of precombustion time interval between the beginning of the fire and the use of the extinguisher;

A gasoline/gas-oil mixture (ratio by weight 2:1) 40 liters of mixture on a base of water;

A gasoline/gas-oil mixture (ratio by weight 1:1) 20 liters of mixture on a base of water;

A, gasoline/gas-oil mixture (ratio by weight 1:1) 60 liters of mixture on a base of water;

A, 'gasoline/gas-oil mixture (ratio by weight 1:1) 50 liters of mixture on a base of water;

A transformer oil, 10 liters:

A gasoline/gas-oil mixture (ratio by weight 1:1) 230 liters of mixture on a base of water;

A gasoline/gas-oil mixture (ratio by weight l-l) 350 liters of mixture on a base of water;

A,, gasoline/gas-oil mixture (ratio by weight 1:1) 400 liters of mixture on a base of water;

A gasoline/gas-oil mixture (ratio by weight 2:1) 900 liters of mixture on a base of water;

A gasoline/gas-oil mixture (ratio by weight 2:1) 600 liters of mixture on a base of water.

All the tests reported on Tables 1 and 3 were carried out by one operator who was at a distance of about 3 meters from the fire tank;

The tests reported on Table. 2 were carried out by one operator (with the exception of tests Nos. 5, 6, 7, 8 and 9 which were carried out by two operators) who was at a distance greater than 3 meters from the fire tank (from about 3 to 5 meters).

The test No. I (Table 2) was carried out in a fire tank of 6 m.'-' (combustion area) provided with a dividing wall located in the middle ofthe tank.

The test No. 5 (Table 2 l was carried out by two operators.

The test No. 6 (Table 2) was carried out by two operators on afire area of 50 m? constituted of a deck house (engine room ofa ship) with all its structures (pipes. grates, etc.

The tests Nos. 7. 8 and 9 (Table 2) were carried out by two operators in a fire tank having St. Andrea's cross shape (X- shape). the arms of the cross being 10 m. X 4 m.; test No. 10 was carried out on the same tank by one operator.

From the preceding Examples and Tables it willbe clearly seen how surprisingly high the efficacy of the extinguishing activity is when the nozzle according to this invention is used.

The advantages of this invention will be evident when it is understood that with the process of the present invention fires of considerable extent (of the order of several tens of m?) may be quenched in a very short time (of the order of a few seconds). with low consumption of extinguishing product (as low as the order of 0.5 kgJmF) andfrom a distance more than sufficient to ensure the safety of the personnel charged with the fire-extinguishing activity (of the order of from 3 to 5 meters). It was also found that for fire areas of large dimensions the elliptical shape of the nozzles orifice is more efficient than the circular shape. 1

The method of this invention extinguishes various kinds of fires including those whose combustible material is a solid (such as paper, wood, fabrics, plastic materials, etc.) those caused by a liquid, a fat or ofelectrical origin and so forth.

We claim:

1. A method of extinguishing fires and quenching flames comprising the step of directing symmetricaldibromotetrafluoroethane thereagainst through a nozzle having a discharge orifice trained on a fire and its flame; and conducting said dibromotetrafluoroethane to said orifice through a chamber of substantially forced conical configuration converging toward and terminating at said orifice while having a conicity angle between about 4 and about 20.

2. The method defined in claim 1 wherein said chamber has a conicity angle ofsubstantially 5 to 18.

3. The method defined in claim 1 wherein said orifice is of circular configuration and said chamber has the configuration ofa frustum ofa right circular cone.

4. The method defined in claim 1 wherein said discharge orifice is of elliptical configuration, said chamber having an inlet orifice of circular configuration spaced from said outlet orifice and forming a smooth transition between the circular inlet orifice and the elliptical discharge orifice.

5. The method defined in claim 4 wherein said discharge orifice has a major half axis and a minor half axis in a ratio of substantially 5:l to lzl.

6. The method defined in claim 5 wherein said ratio ranges between 25:1 to L251].

7. The method defined in claim 5 wherein said chamber has an angle of major conicity and an angle of minor conicity different from one another and each ranging between 4 and 20.

8. The method defined in claim 1 wherein the dibromotetrafluoroethane is forced through said chamber at a pressure of substantially 4 to 20 atm.

9. The method defined in claim 8 wherein said pressure is 6 to l6 atm.

10. The method defined in claim 1, further comprising the step of driving said dibromotetrafluoroethane through said chamber with a propellant insoluble in said dibromotetrafluoroethane and selected from the group which consists of nitrogen helium, another inert gas and air under pressure.

11. The method defined in claim 1 further comprising the step of displacing sald said dibromotetrafluoroethane through said chamber with a propellant partially soluble in the dibromotetrafluoroethane.

12. The method defined in claim 11 wherein said propellant is carbon dioxide.

13. The method defined in claim 1 wherein said dibromotetrafluoroethane is driven through said chamber in said with at least one propellant soluble dibromotetrafluoroethane and selected from the glroup conststing of fluormated, chlorofluormated and bromo uorinated methanes.

14. An apparatus for quenching flames and extinguishing fires comprising a reservoir if dibromotetrafluoroethane and a nozzle for dispensing dibromotetrafluoroethane connected to said reservoir, said nozzle having a nozzle body formed with a discharge orifice and a chamber leading to said discharge orifice and frustoconically converging in the direction thereof with a conicity angle of about 4 to about 20.

15. The apparatus defined in claim 14 wherein said discharge orifice is of circular configuration and said chamber has the configuration of a frustum of a right circular cone.

16. The apparatus defined in claim 14 wherein said discharge orifice is of elliptical configuration with a ratio of its major halfaxis to its minor halfaxis between 5:1 and 1:1.

17. The apparatus defined in claim 14, further comprising pump means for displacing said dibromotetrafluoroethane through said nozzle.

Claims

2. The method defined in claim 1 wherein said chamber has a conicity angle of substantially 5* to 18*.
3. The method defined in claim 1 wherein said orifice is of circular configuration and said chamber has the configuration of a frustum of a right circular cone.
4. The method defined in claim 1 wherein said discharge orifice is of elliptical configuration, said chamber having an inlet orifice of circular configuration spaced from said outlet orifice and forming a smooth transition between the circular inlet orifice and the elliptical discharge orifice.
5. The method defined in claim 4 wherein said discharge orifice has a major half axis and a minor half axis in a ratio of substantially 5:1 to 1:1.
6. The method defined in claim 5 wherein said ratio ranges between 2.5:1 to 1.25:1.
7. The method defined in claim 5 wherein said chamber has an angle of major conicity and an angle of minor conicity different from one another and each ranging between 4* and 20*.
8. The method defined in claim 1 wherein the dibromotetrafluoroethane is forced through said chamber at a pressure of substantially 4 to 20 atm.
9. The method defined in claim 8 wherein said pressure is 6 to 16 atm.
10. The method defined in claim 1, further comprising the step of driving said dibromotetrafluoroethane through said chamber with a propellant insoluble in said dibromotetrafluoroethane and selected from the group which consists of nitrogen helium, another inert gas and air under pressure.
11. The method defined in claim 1 further comprising the step of displacing saId said dibromotetrafluoroethane through said chamber with a propellant partially soluble in the dibromotetrafluoroethane.
12. The method defined in claim 11 wherein said propellant is carbon dioxide.
13. The method defined in claim 1 wherein said dibromotetrafluoroethane is driven through said chamber with at least one propellant soluble in said dibromotetrafluoroethane and selected from the group consisting of fluorinated, chlorofluorinated and bromofluorinated methanes.
14. An apparatus for quenching flames and extinguishing fires comprising a reservoir if dibromotetrafluoroethane and a nozzle for dispensing dibromotetrafluoroethane connected to said reservoir, said nozzle having a nozzle body formed with a discharge orifice and a chamber leading to said discharge orifice and frustoconically converging in the direction thereof with a conicity angle of about 4* to about 20*.
15. The apparatus defined in claim 14 wherein said discharge orifice is of circular Configuration and said chamber has the configuration of a frustum of a right circular cone.
16. The apparatus defined in claim 14 wherein said discharge orifice is of elliptical configuration with a ratio of its major half axis to its minor half axis between 5:1 and 1:1.
17. The apparatus defined in claim 14, further comprising pump means for displacing said dibromotetrafluoroethane through said nozzle.