US 2795350 A
Description (OCR text may contain errors)
June 11, 1957 z. LAPIN 2,795,350
EXPLOSION-PROOF LOW-PRESSURE com'umzns Filed Dec. 2. 1953 u\t -z INVENTOR. ZEVERLY L. LAPIN BY 7 W $4,, ATTORNEY United States Patent EXPLOSION-PROOF LOW-PRESSURE CONTAINERS Zeverly L. Lapin, St. Louis County, Mo., assignor to Development Research, Inc., St. Louis, Mo., a corporation of Missouri Application December 2, 1953, Serial No. 395,687
1 Claim. (Cl. 220-44) This invention pertains to improvements in low-pressure containers, and in particular to an improvement to make such containers explosion-proof.
Low-pressure double-seamed containers are now widely used for packaging and dispensing fluids and gases as used in such products as aerosols, shaving lathers, and food toppings. For the commercial success of such products, it is important that they should be so packaged as to be suited for transport by all convenient and usual means. However, prior to the present invention, it has not been possible to ship such containers packed with fluids and gases by parcel post. Mailing regulations forbid the transport by parcel post of containers which, if subjected to heat, as in a fire, would present a danger of explosion.
Objects of the present invention include: The provision of a simple container whose bottom and side wall are so joined that they will not be separated from each other despite increases of pressure within the container due to externally applied heat; the provision of a feature which safeties the container bottom to the side wall while the pressure in the container permanently distorts the bottom and then escapes from it; and the achievement of the other objects hereof without substantial additional manufacturing expense.
In the accompanying drawings:
Figure 1 is a perspective view partly from below of a low-pressure container embodying the present invention.
Figure 2 is a fragmentary view taken along line 2-2 of Figure 1.
Figure 3 is a perspective view similar to Figure l of the lower portion of such container shown with the bottom everted.
Figure 4 is a fragmentary view taken along line 4-4 of Figure 3.
The container of the present invention is of the singleuse type such as the container generally designated a, formed of light gauge metal and having a tubular side wall 1 whose upper portion is formed inwardly to a mouth 2 into which may be sealedly spun a top closure 3. Any suitable dispensing valve, such as the valve generally designated b may be sealedly mounted in such top closure 3.
The container designated a includes a bottom which is generally designated 4, having a concave center portion 5, an annular band portion 6 which is presented sealedly against and within the lower margin 7 of the side wall 1, and an outer bottom margin 8 which is bent back sharply from the annular band portion 6 around the lower margin 7 of the side wall 1. The sharp bend so made forms a bent-back lower rim 9 upon which the container normally rests. The edges of the lower margin 7 of the side wall 1 and the outer bottom margin 8 are spun together in a spun seam 10, shown in Figure 2.
It has been found that if heat is applied to such a container, filled with substances such as soap and Freon gas under pressures of the order of 50 to 125 pounds per square inch, more or less, the increase in pressure due to the application of heat tends to cause an eversion of the 2 ,795,350 Patented June 11, 1957 concave center portion 5 and annular band portion 6 of the bottom 4. Such an eversion substantially increases the volume of the container and efiects a corresponding reduction in pressure. However, if the application of heat is continued, the bottom 4 will be forced outward from the side wall 1, the spun seam 10 being bent open violently and the bottom 4 being exploded from the container with force and suddenness.
Inasmuch as the bottom 4 is formed of a thin sheet of metal, explosion of the container presents a serious danger of injury to persons who may be in the vicinity. For this reason, such containers not embodying the present invention may not be shipped through the mails.
I overcome this serious deficiency by providing a nick or cut 11 which preferably penetrates only part way through the material and the bent-back lower rim 9 of the bottom 4. Such nick or cut 11 may be imparted to the rim 9 in a variety of ways, as by a radial shallow saw cut, or a simple impact tool. It is apparent from Figure 2 that the side wall 1 is left intact in the region of its lower margin 7 and the seal of the annular band portion 6 against the inner surface of the lower margin 7 of the side wall 1 is in no way disturbed by such nick or cut 11. Therefore, in normal use the container a functions precisely as if the nick or cut 11 was not present.
In the event of fire or other cause tending to increase greatly the pressure within the container a, on the eversion of the concave center portion 5 and annular band portion 6 of the bottom 4, as shown in Figures 3 and 4, the bent back lower rim 9 is caused to be opened and substantially straightened, as shown in Figure 4. This sudden opening and flexing of the bent-back lower rim 9 cracks open the portion thereof which has been weakened by the nick or cut 11, opening said nick or cut 11 to form a pressureventing orifice 12 which penetrates the bottom 4 and has a length at least equal to the developed length of the nick or cut 11 on the inside, bottom, and outside of the bentback lower rim 9. The length of the orifice 12 tends to be increased by the flexure accompanying straightening of the rim 9 and by the intense pressures exerted in the process.
The eversion of the concave center portion 5 and annular band portion 6 of the bottom 4 immediately lowers the pressure within the container a; and with the opening of the nick or cut 11 to form the orifice 12, the container contents are permitted to escape and the pressure lowered to atmospheric pressure.
As is apparent from Figure 4, the change in configuration partly loosens the spun seam 10; but the edges of the bottom 4 and side wall 1 remain in the overlapping relationship shown in Figure 4, so as to safety the bottom 4 to the side wall 1. The container is of course rendered unfit for further use, but nevertheless presents no danger of explosion. Consequently, the purposes of the present invention are achieved without any additional structural components or assembly problems, and without any substantial increase in expense over the manufacturing costs on containers not provided with this improvement.
It being immaterial whether the closure of the side wall to be vented by the nick or cut 11 is the top or the bottom wall, the part referred to in the specification as the bottom 4 is referred to in the claim merely as a sheet metal container end closure.
Other embodiments of the inventive principles herein disclosed will be apparent to those skilled in the art. Accordingly, the present invention is to be considered as coextensive with the inventive principles herein disclosed.
An explosiveproof pressure container, comprising a sheet metal tubular side-wall, a sheet metal end closure having an outer edge portion joined to the side-wall in a seam spun outward of the side-wall, further having a portion adjacent the seam whose inner surface is normally presented sealedly against and in surface contact with the inner surface of the end margin of the side wall, and a nick between the sealedlypresented portion and the outer edge portion, whereby, on generation of excessive pressure within the container, the center portion of the container end closure everts, bending the sealedly-presented portion away from the side wall and causing the nick to vent the pressure within the container, the outer edge portion being retained in the seam to the side-wall, the nick as initially made being only partly through the sheet material of the container end closure, and being opened into a vent by the bending attendant to such eversion.
References Cited in the file of this patent UNITED STATES PATENTS