US2742094A

US2742094A - Appliance for suppression of explosions and prevention of fires

Info

Publication number: US2742094A
Application number: US377203A
Authority: US
Inventors: Mathisen Anders
Original assignee: Graviner Manufacturing Co Ltd
Current assignee: Graviner Manufacturing Co Ltd
Priority date: 1952-09-01
Filing date: 1953-08-28
Publication date: 1956-04-17
Anticipated expiration: 1973-04-17

Description

April 17, 1956 MATHlSEN 2,742,094

APPLIANCE: FOR SUPPRESSION OF EXPLOSIONS AND PREVENTION OF FIRES Filed Aug. 28, 1955 3 Sheets-Sheet l INVENTOR A 7A TV/u-w April 17, 1956 A. MATHISEN 2,742,094

APPLIANCE FOR SUPPRESSION OF EXPLOSIONS AND PREVENTION OF FIRES Filed Aug. 28, 1953 5 Sheets-Sheet 2 INVEN7OR vpf/n 7/9 7/05 April 17, 1956 A. MATHISEN 2,742,094

APPLIANCE FOR SUPPRESSION OF EXPLOSION-S AND PREVENTION OF FIRES Filed Aug. 28, 1953 5 Sheets-Sheet 3 INVENTOR M fl/I fl /raw APPLIANCE FOR SUPPRESSION F EXPLOSIONS AND PREVENTION OF FIRES.

Wilkinson Sword Company Limited, London, England,

a British company Application August 28, 1953, Serial No. 377,203

Claims priority, application Great Britain September 1, 1952 20 Claims. (CL 169-28) The present invention relates to appliances of the kind adapted to contain suppressant for extinguishing fires or suppressing explosions.

In thespecification accompanying patent Serial No. 73,716 there is described an appliance of the above kind which consists of a hemisphere adapted to contain liquid suppressant which may be scattered at a rate of up to 300 ft. per see. when an explosive charge immersed in the liquid is ignited.

One object of the present invention is to provide an improved appliance particularly adapted for use in the suppression of explosions and extinguishing of fires.

According to the present invention there is provided an appliance adapted to contain suppressant for extinguishing fires or suppressing explosions, wherein means are provided for eifecting an initial rapid discharge of a portion of the contents which is followed by arslower butmore prolonged discharge of the remainder of said contents.

1 The invention also provides an appliance adapted to contain suppressant for extinguishing fires or suppressing explosions, comprising a frangible suppressant container, means for fracturing said container to effect rapid dispersal of the suppressant contained therein, and a'fu'rther suppressant container having a discharge orifice normally sealed by said frangible suppressant container, whereby the dispersal of suppressant from said frangible container is followed by ejection of the suppressant from said further container.

.In a preferred form the appliance is provided with a wide-bore discharge orificewwhich. is sealed by an outwardly projecting hollow member containing a proportion of the suppressant and comprises an explosive charge mounted in the discharge-orifice, and means for directing the force of the explosion resulting from ignition of the explosive chargetowards the hollow member to fracture the hollow memberuand to disperse at a rapid rate'the suppressant contained therein, the remainder of the suppressant being discharged at a slower rate determined by the pressure withinrthe appliance.

The member sealing :the discharge orifice may be a hemisphere or othercap of a sphere and may be of frangible material which, according to the material used, may be fractured or "shattered into fragmentsby the ignition of the explosive charge. Thelatter may be of 'the exceptionally fast operating kind generally known as detonators.

Several embodimentsof the presentinvention will -now bedescribed, by way .of example only, withcreference :to the accompanying drawings .in.which:

, EEigure .lshows a sectionalsideelevationtof a preferred construction of the appliance; I

Figure 2 shows diagrammatically one ,possible pattern of discharge of *thezsuppressant from the appliance;

, Figure 3 .:shows ta:sectional:sideelevation :of .a modified fdrrntofrconstructiontofitheiappliance, aWhilSt United States Patent 0 Figure 4 is a similar view of a third possible construction, and

Figure 5 shows a sectional side elevation of yet another possible form of construction,

Referring 'firstly to Figure 1 the appliance shown in this drawing comprises a metal bottle 10 and an elbow fitting 11 which is secured by means of bolts 12 to a flange 13. provided on the neck of the bottle, a sealing gasket 14 ensuring a liquid-tight seal. The other end of the elbow fitting 11 is flanged at 11a to provide means for securing the appliance to a wall 18 of a vessel to be protected adjacent an aperture in the wall 18. An annular sealing gasket 15 for sealing between the flange 11a and the wall 18 is secured to the flange 11a by means of a clamping ring 16 which is bolted to the flange 11a, this clamping ring 16 also serving to secure a thin metal hemisphere, 17 which seals the mouth of the elbow fitting and projects through the aperture in the wall 18. A bushing 11b is formed in the rear wall of the elbow fitting 11 for supportinga helical spreader 19 together with a detonator holder 20 and a terminal block 21 for connection of a firing circuit to the detonator 22. The end face of the helical spreader 19 is formed into a concave reflector 19a to direct towards the hemisphere 17 the force of the eX- plosion resulting from ignition of the detonator, the active end portion of which is located at approximately the centre of the hemisphere,

The detonator holder 20 is secured in a central boring in the spreader 19 by means of a distance tube 23, packing

members

24 and 25, and a sealing washer 26. The spreader 19 is secured in the bushing 11b by a nut 27, a sealing gasket 28 being provided between the mating surfaces of the spreader 19 and bushing 11b. An extension piece 29 is secured to the end of the distance tube 23 and a nut 30 fixes the distance tube 23 in the bore of the spreader 19. The leads from the detonator 22 are connected to the terminal block 21 which is enclosed in a flame-proof junction box 31 having openings 31a through which connecting leads may be passed to the terminal block 21.

The space within the hemisphere 17 and elbow fitting 11 is filled with a suitable liquid suppressant, for example methyl bromide or like halogen suppressants or any other suitable liquid suppressant, the liquid also filling about two-thirds of the bottle. The remaining space within the bottle contains a pressurising gas, such as nitrogen, at a pressureof, for example, 200-250 pounds per square inch at normal temperatures. 2

ignition of the explosive charge may be effected automatically, for example in the case of an incipient explosion it may be effected by a rate of pressure rise detector, such as those described in the aforesaid patent specification, or by means of pressure detectors or flame detectors such as are described in several pending patent applications of the present applicants.

When the explosive charge is ignited, its explosive force is directed by the concave surface 19a of the spreader 19, in a radially outward direction and is transmitted through the liquid contained'in the hemisphere 17 to' cause tearing or shattering of the hemisphere 17 to permit rapid discharge of the suppressant contained in the hemisphere 17 under the action of the explosive force at a rate of as much as 300 feet per second. At the same time, the fracturing of the hemisphere 17 opens the discharge orifice constituted by the mouth of the elbow fitting 11 adjacent flange 11a, so that the suppressant contained within the elbow fitting 11 and the bottle 10 is free to discharge through the orifice under the pressure of the pressurising gas. The operation is such that the liquid within-the hemisphere 17 is discharged at a high velocity under the action of the explosive charge, and at a rapid rate, for example within a period of the order of 20 milliseconds, whilst the remaining major part of the suppressant is discharged more slowly under the action of the pressurising gas, .the follow-up discharge occurring over a longer period, for example of the order of 80 milliseconds, these times being for an appliance containing approximately five litres of suppressant.

It should be emphasised that the mounting of the detonator 22 in the position in which it is shown in Figure l is such that the violent reaction of the explosion of the detonator within a A inch of its outer end ensures that the liquid surrounding this end portion is compressed in all directions, and as the reflector 19a and the liquid cannot yield the liquid is dispersed forward in a more or less perfect hemisphere. The active end portion of the detonator 22 should be mounted sufficiently in front of the reflector 19a to ensure that its explosive force is not dissipated in deformation of the surface of the reflector.

The initial discharge may thus be in the form of a hemispherical pattern, whilst the helical form of the spreader 19 ensures that the follow-up discharge is of hemispherical or sausage shape. Uniformity of discharge is generally essential to suppress an explosion, as otherwise there will be unprotected areas where partial explosions will occur which may be sufficient to cause appreciable damage.

It will be seen that with an appliance of the kind just described it is possible to obtain an initial discharge during which the suppressant is dispersed at a very rapid rate, followed by a more prolonged but slower discharge of the remainder of the suppressant. To appreciate the importance of such operation it should be explained that the applicants have discovered that the speed of propagation of an explosion flame in the initial stages of an explosion is fairly slow, a few feet per second, in a moderate size container. In a small container of, say, five cubic feet the speed of propagation is faster and the dispersal of suppressing fluid must take place with extreme rapidity in order to eflect suppression.

In larger vessels of, say, a hundred cubic feet capacity, the speed of flame propagation is less than in the smaller containers and thus it becomes possible to retard the flame by a first and high speed scattering of suppressing fluid, provided this is followed up with an adequate quantity of suppressing fluid as is the case when using appliances in accordance with the present invention.

If the appliances of the kind shown in Figure 3 of the aforesaid patent specification were used, an objectionably large number would be required in the case of larger vessels, and there would still be the danger that the discharge would not not last long enough to prevent the restrike of a fire. The same advantages are obtained when applying the appliances to the extinction of fires in aircraft, for example in the bays.

The hemisphere 17 may be of a ductile material such as copper or silver, in which case it will tear under the action of the explosive charge. To facilitate even tearing and uniform dispersal, the cup is formed with predetermined lines of weakness which may be effected by scoring, etching or other suitable treatment. Preferably the lines of weakness will radiate from a central point on the surface, so that when fractured the hemisphere may consist of a number of splayed-out petal-like portions. The hemisphere may also be composed of materials such as plastics or glass, which fracture into small pieces.

Figure 2 shows one possible distribution pattern for the suppressant, the shaded area 32 representing the pattern of discharge of the suppressant contained in the hemisphere 17, whilst the shaded area 33 represents the pattern of discharge of the remaining suppressant which is due to the swirling effect produced by the helical spreader 19.

Figure 3 shows an alternative construction to that shown in Figure 2, in which the detonator holder 34. is

supported by a mushroom-like member 35 secured to the back of the elbow fitting 36. The head 35a of the member 35 serves to direct the force the explosive charge radially outwards towards the hemisphere 37. The construction is otherwise generally similar to that of Figure 1 and further description would appear to be unnecessary.

Owing to the presence of the pressurising gas in the bottles, each of the constructions shown in Figures 1 and 3 must be mounted with the longitudinal axis of the bottle roughly vertical. This means that the discharge of suppressant takes place about an approximately horizontal axis. However, there may be cases where discharge in other directions is necessary, more particularly about a vertical axis, and the construction of Figure 1 may be arranged for such discharge by modifying the elbow fitting so that the flange connection to the bottle lies in a plane substantially parallel to the flange connection to the hemisphere, but with the axis of the two flanges offset laterally to allow for the mounting of the detonator holder, spreader etc.

Alternatively, in the case of the Figure 3 construction for example, the bottle together with the opening by which the bottle is connected to the elbow fitting can be omitted. The device is then suitable for mounting so that the discharge orifice lies in a substantially horizontal plane with the terminal block uppermost, so that discharge takes place about a vertical axis.

The Figure 4 construction shows another possible arrangement to enable discharge about a vertical axis. In this case the detonator holder 38 is inserted at an angle into the cup supporting fitting 39 and a plate 40 is secured adjacent the mouth of the discharge orifice to act as a reflector for directing the force of the explosive charge radially downwards towards the hemisphere 41. Naturally an aperture must be provided in the plate 40 to allow discharge of the liquid stored above the plate 40, and such an aperture is indicated at 40a. As a modification of this form of construction (not shown) a reflector plate can be mounted on the detector holder 38 to leave an annular discharge orifice between the plate 40 and the fitting 39.

In certain installations, such as cylindrical tanks, it may be inadvisable to disturb the smooth lines of the inner surface as would be the case if the hemispherical end of the appliance projected into the tank. One possible way to avoid this is to provide a light panel which closes the aperture in the tank, the hemisphere of the appliance being positioned on the outside of the panel with a rigid hood coupled to the main body of the tank and the mouth of the discharge orifice to ensure that on discharge the suppressant enters the tan The arrangement is such that when the explosive charge is ignited to shatter the hemisphere the light panel is blown out to permit discharge of the suppressant through the aperture, the hood ensuring that all the suppressant enters the tank.

As an alternative to such an arrangement the construction shown in Figure 5 may be used, and this comprises a blow-out panel 42 sealing an aperture in a cylindrical tank 43 and also serving to close the discharge orifice of the appliance 44. This blow-out panel 42 takes the place of the hemisphere in the earlier constructions, and the explosive charge 45 is supported further back by a mushroom-like member 46, the head 46a of which forms a concave reflector so that the suppressant liquid in the space between the reflector surface and the blow-out panel 42 is the portion which is discharged at the more rapid rate. The remaining liquid above the level of the reflector discharges more slowly under the action of the pressurising gas. Of course, the blow-out panel can take appropriate shapes other than that shown in Figure 5.

The construction of leak-proof containers subject to gas pressure of up to 500 lbs. per square inch is not easy, and to reduce the risk of leakage a gas generating cartridge may be used, as an. alternative to the use of the "5 pressuri'sin'g gas. The gas'geiieratingea ridge "is fitted Within the appliance and electrically ignited simultaneously with 'th'eexplosive charge to generate a "gas pressiife.

The cartridge would be rapid acting, or in fa'c't almost explosive in the initial stage of operation, gas generation, however, continuing for as long as a second or two to maintain a gas pressure in the container of over 100 lbs. per square inch until the contents is discharged.

What is claiiiied ia: I i

1 In an appliance adapted to contain suppressant for extinguishing fires and suppressing-incipient explosions, a frangible suppressant container, means for fracturing said container to effect rapid dispersal of the suppressant contained therein, and a further suppressant container, said further suppressant container having a discharge orilice normally sealed by said frangible suppressant container whereby the dispersal of suppressant from said frangible container is followed by ejection of the suppressant from said further container.

2. An appliance according to claim 1, in which said means for fracturingsaid frangible container is an electrically ignitable explosive charge.

3. An appliance according to claim 1, wherein said frangible suppressant container is a hollow member in the shape of a cap of a sphere.

4. An appliance according to claim 3, in which said member is composed of ductile metal.

5. In an appliance containing fire extinguishing fluid for extinguishing fires and suppressing explosions, said appliance having a wide-bore discharge orifice, an outwardly projecting hollow member sealing said orifice,

said hollow member containing fire extinguishing fluid, an explosive charge mounted in the discharge orifice, and means for directing the force of the explosion re sulting from ignition of the explosive charge towards the hollow member whereby the hollow member is fractured and the fluid contained therein dispersed at a rapid rate prior to the dispersal of the remainder of the fluid contained within the appliance.

6. An appliance according to claim 5, wherein the means for directing the force of the explosion comprises a rigid member positioned on the opposite side of the explosive charge to that on which said hollow member lies.

7. An appliance according to claim 5, wherein the hollow member sealing the discharge orifice is of ductile metal.

8. In an appliance adapted to contain liquid suppressant for extinguishing fires and suppressing incipient explosions, said appliance having a wide-bore discharge orifice, a closure member sealing said orifice and in contact with said suppressant, an explosive charge mounted at an appreciable distance from said closure member, said explosive charge being surrounded by suppressant, and pressure wave directing means for directing towards said closure member the force of the explosive charge resulting from ignition thereof, whereby said explosive force fractures said closure member and effects rapid discharge of that portion of the suppressantintermediate said charge and said closure member, the remainder of the suppressant being discharged at a slower rate determined by the pressure within the appliance.

9. An appliance according to claim 8, wherein the closure member sealing the discharge orifice has the shape of a cap of a hollow sphere.

'10. An appliance according to claim 8, comprising a gas generating cartridge positioned within the interior of the appliance, whereby ignition of the gas generating cartridge produces an elevated gas pressure within said appliance.

11. In a fire extinguishing fluid appliance, a hollow cylindrical container permanently closed at one end and open at the other end, a frangible cup member having a rim sealed to said cylindrical container for closing said open end, fire extinguishing fluid completely filling said cap member and '-par't'ially filli'ng; rain win-ants; aoinaine'r, are portion or the space "withinnaid cylindrical container "which is not filled "with fluid using" occupied by gas at superannospheric pressure; and an explosive charge mounted within the fluid contained in said cap member whereby 'upon ignition of said xplos'ive'chalgge said cup member is fractured and its-fluid coirteiits is "dispersed, the fracturing of the cap "member also releasing the fluid contents er said cylindr icalcoiitainr.

l2.Iri a fire extinguishing flu'id applia 'c'e', a hollow cylindrical container painlessly cldsd av c -end and open at the other "end, a f'ra'iigible "cup member having a rim scaled to said cylindrical container for closing said open end, fire extinguishing fluid completely filling said cup member and partially filling. said cylindrical container, the portion of the space within said cylindrical container which is not filled with fluid being occupied by gas at super-atmospheric pressure, an explosive detonator mounted within the open end of said cylindrical container and spaced from said cup member, an explosive force reflecting member mounted adjacent said detonator for reflecting towards the cup member the force of an explosion resulting from its ignition whereby said cup member is fractured and its fluid contents is dispersed, the fracturing of the cup member also releasing the fluid contents of said cylindrical container.

13. An appliance according to claim 12, in which said cup member is composed of ductile metal and has the shape of a cap of a sphere.

14. An appliance according to claim 12, in which liquid directing means is provided for directing the portion of the extinguishing fluid discharged after the initial rapid discharge in a predetermined spray pattern.

15. An appliance according to claim 12, in which said directing means comprises a portion of helical thread.

16. The method of suppressing an incipient explosion which comprises effecting an initial discharge of fire extinguishing fluid into the Zone of the incipient explosion -at an extremely rapid rate, and thereafter efiecting a greater quantity of fire extinguishing fluid into said zone at a lower rate of initial discharge.

18. In an appliance adapted to contain suppressant for extinguishing fires and suppressing incipient explosions, a frangible hemispherical ductile metal suppressant container, an electrically ignitable explosive charge mounted approximately at the centre of curvature of said ductile metal suppressant container, and a non-frangible metallic suppressant container having a substantially greater volume than that of said frangible suppressant container, said non-frangible suppressant container having a discharge orifice. closed by said frangible suppressant container whereby the explosive force resulting from electrical ignition of said explosive charge shatters the frangible suppressant container, distributes the suppressant contained therein at a rapid rate, and simultaneously opens the discharge orifice of said non-frangible container for permitting a slower and more prolonged discharge of the suppressant contained in said non-frangible container.

19. In an appliance adapted to contain suppressant for extinguishing fires and. suppressing incipient explosions, a non-frangible metallic suppressant container partly filled with suppressant liquid, the remaining space within said container being occupied by gas at superatmospheric pressure, said non-frangible container having a normally closed discharge orifice through which the suppressant liquid is forced by said gas upon opening of said orifice, a tearable ductile metal closure member normally closing said orifice, said closure member having the shape of a'cap of a sphere and being mounted with its convex surface in contact with the suppressant liquid, an electrically ignited explosive charge, a supporting member for said explosive charge, said supporting member being secured to said non-frangible container andsupporting said explosive charge substantially centrally in said discharge orifice, whereby upon ignition of said explosive charge the resultant force is transmitted through the liquid lying between the explosive charge and said closure member to tear the latter memher and initiate discharge of the suppressant.

References Cited in the file of this patent UNITED STATES PATENTS Delbare Apr. 24, 1923 Buddecke Apr.,9, 1929

Claims

1. IN AN APPLIANCE ADAPTED TO CONTAIN SUPPRESSANT FOR EXTINGUISHING FIRES AND SUPPRESSING INCIPIENT EXPLOSIONS, A FRANGIBLE SUPPRESSANT CONTAINER, MEANS FOR FRACTURING SAID CONTAINER TO EFFECT RAPID DISPERSAL OF THE SUPPRESSANT CONTAINED THEREIN, AND A FURTHER SUPPRESSANT CONTAINER, SAID FURTHER SUPPRESSANT CONTAINER HAVING A DISCHARGE ORIFICE NORMALLY SEALED BY SAID FRANGIBLE SUPPRESSANT CONTAINER WHEREBY THE DISPERSAL OF SUPPRESSANT FROM SAID FRANGIBLE CONTAINER IS FOLLOWED BY EJECTION OF THE SUPPRESSANT FROM SAID FURTHER CONTAINER.