US 3189210 A
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Description (OCR text may contain errors)
June 15, 1965 J. 5. HEISLER VENTING CLOSURE FOR CONTAINERS Filed Feb. 15, 1963 INVENTOR. S HE/SAER Arm/Wab- III! 4 v /llll (/Z PONE 65 Min J94 I II VV VIH United States Patent This invention relates to containers and more particularly to the provision of a reliable venting closure capable of permitting the escape of gas from the container but not the fluid contents thereof.
It is now common practice to transport valuable fluids and chemicals which are corrosive or easily contaminated, in large drums and containers made of thermoplastic materials which are chemically inert, and while these materials, such as for example polyethylene, are relatively soft and deformable, they are flexible, strong and practically unbreakable. These thermoplastic containers or drums are usually provided with one or more openings for use in filling and emptying the container. These openings are usually defined by flanges which are often provided with an exterior thread to accommodate a closure cap made of a suitable thermoplastic material such as polyethylene and capable of effectively sealing the dangerous contents of the containers against leakage or spill- 3 age during handling. It happens however, that certain of the compounds shipped in these thermoplastic containers or drums, such as ethyl chloroforrnate, sodium hypochlorite, hydrochloric acid, and hydrogen peroxide, are gas generating compounds, and will build up in a 7 container gas pressures of one half pound per square inch and greater over a period of time. Due to the inherently dangerous nature of such compounds it is necessary that such pressures be relieved without such loss in the effectiveness of the seal provided by the closure cap that the compound itself could escape from the container. On the other hand, there is the situation in which a compound is packed under relatively high heat conditions and shipped to a destination which is of such low temperature that a partial vacuum is created in the container. When this occurs it is sometimesnecessary that the vacuum be eliminated before the contents of the container can be safely withdrawn.
It is accordingly the primary purpose of this invention to provide a cap-like closure which is capable of forming on the flange of a polyethylene container an effective liquid tight seal and yet which is able to vent to prevent the formation of extraordinary gas pressures in the container without destroying the effectiveness of the liquid seal.
For a better. understanding of the invention, as well as the novel features thereof, reference is made to the fol-' lowing description which should be read in connection with the accompanying drawings, in which FIG. 1 is a central vertical sectional View of the upper end of a container provided with a closure embodying the invention and showing the relation of the closure parts when normal conditions exist in the container;
FIG. 2 is a similar view in a reduced, partly diagrammatic, scale showing the condition of the closure parts when a small, or harmless gas pressure exists in the container;
FIG. 3 is a view similar to FIG. 2 showing the manner in which the closure vents when the gas pressure in the container is too high;
FIG. 4 is a view similar to FIGS. 2 and 3 showing the condition of the closure parts when a partial vacuum exists in the container; and
FIG. 5 is a central vertical section of an inner sealing member forming part of the closure.
In the drawings, the numeral 10 designates generally a. container made of any suitable elastomeric material of a chemically inert nature, such as polyethylene. The outlet opening of the container is defined by a flange 11 also molded of a chemically inert plastic material, preferably polyethylene because it is soft and flexible and yet strong. The flange 11 may be integrally molded to the material of the container body 10, or may be molded separately therefrom and subsequently attached to the container body in any suitable manner known to the art. The exterior of the cylindrical body or wall constituting the flange 11, as shown, is provided with coupling means in the form of a suitable thread 12 of the buttress type. i It will be understood however, that the thread 12 may be of any other suitable type, such as, a regular 60 V thread, a round thread, or a square thread. It is also within the contemplation of the invention to utilize other coupling means known to the art in place of screw threads.
It is to be noted that the interior surface 13 of the flange 11 is a straight, smooth cylindrical surface, at least in the upper portion of the flange, and that at the top of such flange there is provided an annular seating surface 14 disposed substantially at right angles to the vertical, and of a width substantially equal to the thickness of the flange body or wall between such interior surface 13 and the root line of the thread 12. It will be further noted that the start of the thread 12 is adjacent to said seating surface 14.
Seated on the annular surface 14, is an outwardly projecting annular flange 21 provided on the top end of a cup-shaped sealing member designated generally by the numeral 20 and also constituted of polyethylene; such flange being disposed at substantially right angles to the vertical axis of such member. The body 22 of the sealing member 20 is circular in horizontal section and converges downwardly and inwardly from the flange 21 so that it has a frusto-conical configuration. The wall of body 22 is not straight lengthwise, but is slightly curved so that its exterior surface is convexly shaped lengthwise. At its upper end, the wall of body 22 has a thickness approximating the thickness of flange 21. The thickness of such wall gradually increases toward its bottom end to a thickness almost twice that of its upper end. Thus, the
wall of body 22, because of its gradual reduction diameter and its gradual increase in thickness towards its bottom end, progressively becomes more rigid towards such bottom end. i
The circular bottom wall 23 of the sealing member 20 has a thickness substantially the same as that of the bottom end of body Wall 22. Bottom wall 23 has a slightly convex configuration, as viewed from the top of the sealing member, and has a diameter substantially less than the diameter of the interior surface 13 of the flange 11 so that the peripheral bottom edge of the sealing member is spaced from such interior surface. Thus, if we assume that thediameter of the surface 13 is 2.385 inches, a suitable outside diameter for the bottom end of the sealing member 20 is in the neighborhood of 2.275 inches. The external diameter of the body wall 22 will gradually increase from such dimension at a rate such that about midway in the height of such wall its external diameter will approximate the diameter of the interior surface 13. At its upper end, the body wall 22 will have an external diameter greater than that of the interior surface 13, say of the order of 2.425 inches for the given diameter of such surface. As a result of such dimensions, when the sealing member 20 is inserted in position in the flange 11 with the flange 21 thereof seated on. surface 14, the body wall 22 thereof will be distorted from the shape shown in FIG. 5 to the configuration shown in FIG. 1. In such condition the upper portion of such body wall will form an air-tight, liquid-tight seal with the interior flange surface 13. As the height of wall 22 is approximately one inch, the width of such seal will be approximately one half inch. The seal throughout such width will be substantially uniform due to the gradual difference in thickness of the wall 22 and the gradual difference in the external diameter of such wall throughout such width. It will be understood, that by varying the dimensional factors, the pressure that the wall 22 exerts on the flange surface 13, throughout the width of such seal, can be varied to adjust the seal to any given gas pressure that it may be desired to maintain in the container.
The associated closure cap is indicated generally by the reference numeral 36 and like flange 11 and sealing member 2% may be made of relatively soft, deformable plastic material, such as polyethylene. The cap 30 comprises an outer cylindrical wall 31 provided with an internal thread 32 which complements the thread 12 formed on the flange 11. Adjacently above the upper terminal end of the thread 32 is a concave groove 33 which overhangs the flange 11 and receives the flange 21 of sealing member when the cap is screwed into position on the flange. The inner side of the wall of groove 33 merges smoothly into the upper end of the outer inwardly inclined wall 34 of a tapered downwardly extending conical member 35. The configuration of the inclined annular wall formed by the combination of the outer wall 34 of member and the inner side wall of groove 33 is such that as the cap 30 is screwed into fully closed position on the flange 11, such annular wall will come into engagement with the annular corner 24 formed at the inner periphery of the flanged end of the sealing member 20 and bear against the same with sufficient pressure to cause the seal formed by flange 21 and body wall 22 with the flange seating surface 14 and the interior flange surface 13, respectively, to withstand a given gas pressure in the container 10.
It will be understood from the foregoing description of the parts, that when the sealing member 20 and the closure cap 39 are assembled on the flange 11, the parts will have the relation shown in FIG. 1. In such relation, the upper portion of body wall 22 will be pressed in sealing engagement against the flange interior wall 13, and the flange 21 will be seated in sealing engagement on the flange surface 14. By designing the sealing member 20 and closure cap 36 properly, the seal thus formed will be liquid tight and will be gas tight for a given gas pressure within the container. In FIG. 1 the condition of the parts are shown when there is little or no gas pressure in the container and the sealing member 20 and closure cap 30 function solely as a liquid seal. When there is a small gas pressure in the container, below that which the parts are designed to relieve, as is indicated by the arrows 46 in FIG. 2, the sealing action of the member 20 and cap will not be rendered less effective, but will in fact become enhanced. This is believed to be due to the fact that the pressure of the gas on the relatively large area of the bottom 23 of the sealing member, will raise the same slightly, while the cap 30 maintains the upper edge of the sealing member seated on the flange seat 14, with the result that more of wall 22 will come into sealing engagement with the interior surface 13 and thus increase the effective area of the seal.
However, when the gas pressure in the container rises above that which the parts were designed to maintain, as indicated by the longer arrows 41 in FIG. 3 of the drawings, such pressure, even though acting on the bottom 23 to tend to increase the seal, will be greater than the transverse sealing force which the wall 22 is able to apply to the flange surface 13, with the result that the wall 22 will be forced inwardly away from surface 13, and the flange 21 will be deflected away from flange surface 14 sufficiently to permit the gas to leak up between wall 22 and surface 13 and around the top of flange 11 between flange 21 and surface 14, the gas thus released leaking through the mating surfaces of the threads 12 and 32 as is indicated by the arrows 41 in FIG. 3. While the gas pressure in the 4% container is thus relieved, it will be understood that the flange 11, sealing member 20 and cap 30 will still function to prevent the discharge of any liquid from the container.
FIG. 4 of the drawings illustrates what occurs when a substantial vacuum is created in the container, such as might occur for example if the contents of the container are loaded in the container under high temperature conditions and the container has been delivered to a destination where very low temperatures prevail. As a result of the vacuum, the bottom 23 will be bowed downwardly and the sealing member 2t! drawn into the flange 11, thus breaking the sealing relation of the wall 22 and flange 21 of such member with the interior surface 13 and seating surface 14 of the flange 11, respectively, and permitting the atmosphere to leak through the threads 12 and 32 and into the container, as is indicated by the arrows 42 in MG. 4, until suitable pressure conditions have been restored in the container.
While I have hereinabove described and illustrated in the accompanying drawings, a preferred embodiment of my invention, it will be apparent to those skilled in the art that modifications and changes may be made in such embodiment without departing from the spirit of the invention, or the scope of the appended claims.
1. In a container structure, a tubular neck defining an opening in the container and constituted of flexible elastomeric material and having a seating surface at its upper end, a cup-shaped sealing member constituted of flexible elastomeric material and having at its upper end an outwardly extending flange seated on said tubular neck seating surface, the body of said sealing member being of tubular configuration and having a flexible upper portion bearing against the interior surface of said neck at a given pressure such as to provide a ga tight, liquid tight seal for a given normal range of gas pressures within the container, and yieldably withdrawable from such sealing engagement with such interior surface when such member is subjected to a gas pressure within the container outside such given range to permit the passage of gas therebetween, the exterior surface of the lower portion of said sealing member being spaced from said interior surface of the neck to facilitate the entry and escape of gas of high pressure between said upper porion and said interior surface, and a closure cap constituted of elastomeric material and having an outer depending wall coupled to said tubular neck, said closure cap having an inwardly tapered frusto-conical wall portion engageable with the inner peripheral edge of the flange on said sealing member to normally hold such flange seated in sealing relation on said neck seating surface when the gas pressure within the container is within said normal range and permitting such seated flange to move relative to said seating surface to enable the passage of gas therebetween when such gas pressure is outside such normal range, said closure cap having an interior annular groove adjacently enclosing said tapered wall portion thereof and overlying said neck seating surface, the outer periphery of said sealing member flange being short of the outer edge of said groove to enable movement of said flange from said seating surface and into said groove to permit such passage of gas therebetween.
2. Container structure such as defined in claim 1, in which the tubular body of said sealing member ha an inwardly tapered frusto-conical shape, the exterior diameter of said body above a point substantially spaced from the upper end thereof being equal to the interior diameter of said tubular flange so that said tubular body above such point is deformed from its normal configuration by said tubular flange.
3. Container structure such as defined in claim 2, in which the wall of said tubular body is bowed lengthwise so that said body is convexly-shaped lengthwise of the same.
4. Container structure such as defined in claim 1, wherein said tubular body has a disc-shaped bottom which is bent upwardly to provide such bottom with a convex shape as viewed from the top of said body.
5. In a container structure, a tubular flange or neck defining an opening in the container and constituted of flexible elastomeric material and having a seating surface at its upper end, a cup-shaped sealing member constituted of flexible elastomeric material and having at its upper end an outwardly extending flange seated on said tubular flange seating surface to support said member in depending relation within said tubular flange, the body of said sealing member being of tubular configuration and at its upper portion bearing against the interior surface of said tubular flange with suflicient pressure to provide a gas tight, liquid tight seal, the tubular body of :said sealing member having an inwardly tapered frustoconical shape and progressively increases in thickness from the upper end thereof, the exterior diameter of said body above a point substantially spaced from the upper end thereof being equal to the interior diameter of said tubular flange so that said tubular body above such point is deformed from its normal configuration by said tubular flange, the exterior surface of the lower portion of said sealing member being spaced from said interior surface of the tubular flange to permit gas of high pressure to enter between said tubular body and said interior surface, and escape past the upper portion of said sealing member, and a closure cap constituted of elastomeric material and having an outer depending wall coupled to References Cited by the Examiner- UNITED STATES PATENTS 2,738,091 3/56 Mattox 215-56 2,941,689 6/60 Black 220--23 3,107,022 1 0/63 Wandell 215-43 TI-IERON E. CONDON, Primary Examiner.