US 3641935 A
A pressure cartridge containing solid fuel for the production of a propellant gas, particularly for use in fire extinguishing devices, including a case constructed from a synthetic resin material, a bottom plate connected to the case in a form-locking manner, and a primer charge.
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United States Patent 1 Feb. 15,1972
2,942,547 6/1960: Rabem etal. ...Q.Lu 92139 Williams et a1. 102/39 Primary Examiner-Robert F. Stahl Attorney-Craig, Antonelli and Hill ABSTRACT A pressure cartridge containing solid fuel for the production of a propellant gas, particularly for use in tire extinguishing devices, including a case constructed from a synthetic resin material, a bottom plate connected to the case in a form- Gawlick et a1.
 PRESSURE CARTRIDGE CONTAINING 2,974,592 3/1961 SOLID FUEL PROPELLANT CHARGE 3339387 9/ 1967 3,340,809 9/1967  Inventors: Heinz Gawlick, Furth; Gunther Marondel, 3 410 213 11 9 Erlangen; Hans Umhacll, Stadeln, all of 3 4 5 1 Germany 3,478,686 11/1969  Assigna: Dynamlt Nobel Aktiengesellsehalt,
Troisdorf, Germany [221' Filed: June 23, I969  Appl.No.: 835,654
 U.S.Cl. ..l02/39,60/37.46  Int. ..F42b9/l8  FieldoISeaIdl ..102/39,41;60/39.46, 39.47
 References Cited U H' ST T,.
locking manner, and a primer charge.
7 5Claims,4 DrawingFigures INVENTORS HEINZ GAWLICK GUNTHER MARONDEL HANS UMBACH PATENTEUFEB 75 I972 FIG. I
ATTORNEYS PRESSURE CARTRIDGE CONTAINING SOLID FUEL PROPELLANT CHARGE BACKGROUND OF THE INVENTION Conventionally, gases stored in a compressed state within steel, cylinders are utilized as-propellant gases in manually operated fire extinguishing devices. When the extinguisher is used, the propellant gases are permitted to escape through a valve into' the tank filled with a fire extinguishing composition, forcing the fire extinguishing composition, under pressure, through a noule in the form of a spray. It has been found, however, that it is virtually impossible, by relatively simple technological means, to store gas under relatively high pressure for prolonged periods of time without experiencing a decrease of the pressure level. Of course, in certain applications, such 'as fire-extinguishing devices, which are acquired merely as a safety measure and employed only in rare instances, it is extremely-essential that the devices remain functional over prolonged periods of time. Thus, fire extinguishing devices of thetype mentioned above must be tested from time to time in order to determine if they arefunctioning properly and, if necessary, must be recharged with a pressure medium.
. It has also been demonstrated that fire-extinguishing devices utilizing C0 as the pressurized gas are not reliable in operation, particularly when the devices are exposed to extremely low temperatures. Accordingly, fire-extinguishing devices have been produced which utilize a solid media to generate the propellant gas, as needed, by combustion of the solid substance. The-solid charges employed in these conventional devices are accommodated within cases and can be inserted in corresponding cartridge chambers provided within the fire extinguishing devices.
The solid fuel employed within such devices may include a nitrocellulose powder or a mixture of ammonium nitrate with various catalysts or other gas-generating products. It is important to select the composition of the solid fuel so that, upon combustion, no flammable gases are produced and no noxious gases are produced. Additionally, the gases should contain a minimal amount of water vapor. Further, the temperature of the gases-produced must not rise to such a degree that the tire extinguisher may be damaged or the individual handling theextinguisher may be hampered.
One of the problems encountered in the design and construction of effective fire-extinguishing devices of the typementioned above involves the construction of the pressure cartridge containing the solid fuel to ensure that the evolution of the gas takes place in the manner desired in emergency use. It is,-of course, additionally desirable that the pressure cartridges be constructed so that they may be stored in relatively large quantities without incurring a substantial risk of a mass explosion.
Accordingly, it is an objective of the present invention to provide a solid fuel-containing pressure cartridge for use in a fire extinguishing device which ensures that the evolution of the gases produced occurs in a predetermined manner.
Further, it is an objective of the present invention to provide a cartridge of the type-mentioned above which may be stored in large numbers without fear of chain explosions.
Finally, it is an objective of the present invention to provide a cartridge of the type mentioned above which ensures a uniform progressive combustion of the solid fuel and theevolution of the propellant gases produced thereby.
SUMMARY OF THE INVENTION The aforementioned objectives are accomplished, in accordance with the present invention, by constructing the case from a synthetic resin material and providing the case with readily destructible diaphragmlike zones distributed over the circumference of the case, which zones, easily destroyed thermally and/or mechanically, provide for the escape of the propellant gas.
Since the pressure cartridge constructed in accordance with the present invention includes a case fabricated from a synthetic resin, it exhibits desirable thermal, insulation between the interior of the case where the combustion is taking place and the exterior thereof where the fire-extinguishing composition is disposed. When a metallic case is utilized, similar thermal insulation properties can be attained only with great difficulty by employing a structurally complex design. The synthetic material contemplated by the. present invention exhibits a substantially greater thermal inertiathan metal, thus permitting the thermal energy developed during combustion to remain within the case and-giving riseto a twofold benefit. First, the thermal insulation promotes a continuous combustion of the solid fuel resulting from the uniform preheating of the fuel; second, the fire-extinguishing composition remains relatively cool.
Preferably, the readily destructible zones are disposed betweenthe solid propellant charge and the bottom plate and the case is provided with a plurality of longitudinally extending ribs which abut the inner wall of a metallic cartridge chamber and define therebetween a plurality of corelike channels. As the gas pressure builds up after ignition, the readily destructible zones burst and the gas escapes into the fire-extinguishing composition through the corelike channels. This assumes that .the pressure cartridge is disposed within the cartridge chamber, of thefire-exting'uishing device for use.
During storagev of the pressure cartridges, the readily destructible zones constitute a part of the wall so that if an explosion occurs within the storage area or a fire breaks out, the zones are destroyed by the rising gas pressure, but the gas can escape without the necessity of overcoming a substantial resistance to flow. Thus, the pressure cartridge contemplated by the present invention affords the significant advantage of a reduced danger of chain explosions of a large number of cartridges stored in closely adjacent, or abutting, relationship. This reduced risk of chain explosions is directly attributable to the possibility of ready expansion of the gases generated within the cartridge.
When the cartridge case is disposed within the chamber of the. fire extinguishing device, forming the aforementioned corelike channels, the gas traveling through these channels is cooled by contact with the metallic wall,,thus preventing a sudden increase in gas pressure such as to cause the case to burst. Thus, the novel construction effectively insures a controlled combustion.
BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objectives, features and advantages of the present invention will become more readily apparent from a consideration of the detailed description hereinbelow, when considered in conjunction with the accompanying drawings, wherein:
FIG. 1 represents a longitudinal sectional view of a pressure cartridge constructed in accordance with the present invention disposed within a cartridge chamber of a fire-extinguishing device;
FIG. 2 represents a section along line II-II of FIG. 1;
FIG. 3 represents a section through the cartridge case, on an enlarged scale; and
FIG. 4 represents a section along line IVIV of FIG. 3.
DETAILED DESCRIPTION OF THE DRAWINGS In FIG. 1, reference numeral 10 denotes a substantially cylindrical cartridge chamber fabricated from metal and tapering to a point at its lower end; the pressure cartridge enclosed by the cartridge case 9 is inserted within cartridge chamber 10. One end of cartridge case 9 is closed off by means of a bottom plate 2; a primer cap 1 is secured substantially in the center of bottom plate 2. From the primer cap 1, an innertube 6, filled with an igniter substance 12, extends to a nipple 16 disposed at the lower front end of the case 9. The inner tube 6 is placed upon nipple 16 so that a tight seal is formed therebetween.
The inner tube 6 is surrounded by a solid fuel composition 1 1 which may consist of a granulated mass or a pressed body. The solid fuel composition or propellant charge 11 is covered by a disklike lid of a synthetic material and a compression spring 4 is disposed, in tension, between the synthetic resin lid 5 and the bottom plate 2 in order to compensate for volumetric variation.
The upper portion of the synthetic resin case 3 is provided with a relatively thick wall, the outer contours of which extend downwardly into four ribs 13 distributed about the circumference of the case. The ribs 13 and the inner surface of the wall of the cartridge chamber define therebetween four corelike channels 7 extending in the longitudinal direction of the chamber and terminating in the pressure space 14 disposed beneath the cartridge case 9 within the cartridge chamber 10. The pressure space 14 includes four circular exit openings 17 terminating in the interior of the fire-extinguishing device.
At the opposite end of the solid propellant charge, the wall of the cartridge case 9 is constructed with a relatively thin wall section between the ribs 13, thus providing readily destructible zones 8 which will burst when the gas pressure reaches a predetermined level in the gas evolution chamber 15, and permitting the gas to flow through the burst zones 8 into the corelike channels 7 and from there through the pressure space 14 into the body of the fire-extinguishing device. At the lower portion thereof, the zones 8 are limited by ribs 9 projecting into the interior of the cartridge case. As can be seen from FIG. 3, the ribs 9 are provided only in the area of the zones 8.
It should be apparent that the entire case 9 is constructed so that it may be manufactured, with relatively simple tools, by means of an injection molding process.
The following is an example of suitable compositions for the solid fuel or propellant charge 1 1:
78.5 percent ammonium nitrate 9 percent potassium nitrate 6.9 ammonium oxalate as an inert substance, evolving gas at higher temperature.
5.6 percent ammonium dichromate as a catalyst, maintaining the progress of the charge decomposition.
The following is an example of a suitable composition of the igniter mixture 12: a metallic oxide, such as lead oxide, copper oxide or iron oxide, and metallic components, such as silicon, boron, zirconium hydride, etc.
The propellant charge 1 1 is ignited by impact upon the primer cap 1 and ignition of the igniter mixture 12. The increasing pressure forces the lid 5 upwardly, against the force of the compression spring 4, eventually destroying the zones 8 and permitting the escape of the gas through the channels 7. Thus, a continuously flowing gas stream is produced and a uniform combustion within the case 9 is attained.
Of course, the number of ribs 13 is not limited to the illustrated example. The sole factor to be considered in this regard is that the proportion of the rib sections with respect to the entire circumference of the case should be no less than about percent.
While the present invention has been described with reference to but a single embodiment thereof, it is to be clearly understood that the scope of the invention is not limited to the specific details illustrated, but is susceptible of numerous changes and modifications as would be apparent to one with normal skill in the pertinent technology.
What is claimed is:
1. A pressure cartridge containing a solid propellant charge which generates a propellant gas upon combustion, particularly, for use in fire-extinguishing devices as the means for propelling the fire-extinguishing substance under pressure comprising: a metallic cartridge chamber; a substantially cylindrical case means fabricated from synthetic resin material including readily destructible regions distributed about the circumference near a first end thereof and at least two external longitudinally extending ribs positioned to define together with the internal surface of said metallic cartridge chamber a corelike channel means, said solid propellant charge being disposed in said case means between said readily destructible regions and a second end thereof; bottom plate means sealingly engaging said case means at said first end thereof in a form-locking manner; and primer cap means for igniting said fuel upon impact.
2. A pressure cartridge according to claim 1, wherein said case means includes a relatively thick wall section between said readily destructible regions and said bottom plate means, the thickness of said section being substantially equivalent to the thickness of said external ribs, whereby said external ribs effectively separate said readily destructible regions from one another.
3. A pressure cartridge according to claim 2, wherein said case means further includes internal, longitudinally extending ribs spaced about the circumference of said case means in alternative relationship with said external ribs, said internal ribs terminating adjacent said readily destructible regions.
4. A pressure cartridge containing a fuel which generates a propellant gas upon combustion, particularly for use in fireextinguishing devices as the means for propelling the fireextinguishing substance under pressure comprising: case means fabricated from a synthetic resin material, said case means being substantially cylindrical in configuration and including readily destructible regions distributed about the circumference thereof, bottom plate means sealingly engaging said case means at one end thereof in a form-locking manner, primer cap means for igniting said fuel upon impact, a disclike lid disposed between said fuel and said bottom plate means, and spring means adapted to compress said lid against said fuel during the combustion thereof until sufficient counterforce is generated by said propellant gas.
5. A pressure cartridge according to claim 4, further comprising a tubular member extending through said propellant charge to said primer cap, said tubular member containing an ignition charge.
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