US 3709395 A
The invention relates to a cap assembly for a biological culture container, preferably a container for the cultivation of microorganisms from blood samples, where the cap assembly includes a cap with a central aperture. A rubber grommet is situated in the aperture. The grommet is symmetrical, is dimensioned to perform reliably under high vacuum or high pressure within the container. It may also be provided with a recess to facilitate penetration by a hypodermic needle or syringe.
Description (OCR text may contain errors)
United States Patent 1191 Brennan et a1.
1111 3,709,395 1451 Jan. 9, 1973  CLOSURE FOR CONTAINERS  inventors: Timothy A. Brennan, Andover,
Mass.; Elmer R. Green, Lowell, Mass.
 Assignee: Hospital Service Technology Corporation, North Andover, Mass.
 Filed: July 1, 1971 i 211 App]. 110.; 158,861
['52] US. Cl. ..2l5/38 R FOREIGN PATENTS OR APPLICATIONS 1,077,767 11/1954 France ..2l5/43R 901,128 10/1944 France ..2l5/43A Primary ExaminerM. Henson Wood, Jr. Assistant Examiner-John J. Love Attorney-Abraham Ogman  ABSTRACT The inventionrelates to a cap assembly for a biological culture container, preferably a container for the cultivation of microorganisms from blood samples,
, where the cap assembly includes a cap with a central aperture. A rubber grommet is situated in the aperture. The grommet is symmetrical, is dimensioned to perform reliably under high vacuum or high pressure within the container. It may also be provided with a recess to facilitate penetration by a hypodermic needle or syringe.
3 Claims, 3 Drawing lFigures PMENIEDJM m5 3.709.395
mum!!! INVENTORS I HY A. BRENNAN ATTORNEY 1/ BY r 157 EL E R. GREEN Classically, two types of closures are used for culture containers. The first type uses a rubber or elastomeric stopper force fitted into the neck of a bottle.
The second prior art closure usesa flat rubber or elastomeric diaphragm held in place on the topof a bottle by a screw cap having a central opening.
These prior art closures are difficult to use in the preparation of the culture containers and in their use.
Bottles with a stopper often explode-or blow the stopper and boil over when autoclaved as the culture medium boils. In either case the container is rejected for use.
Removal of the stopper to remove samples for examination risks aerosol generation of micro-organisms when the stopper is pulled. Additionally, once removed the stopper is difficult to replace and can introduce extraneous micro-organism contamination. These limitations preclude the use of a sterile loop or pipette to remove a sample.
Considering the diaphragm construction and steam autoclaving, the diaphragm has a tendency to be pulled into the bottle when a partial vacuum forms when the. bottle cools.
Additionally, the problem is aggrevated by the unreliability of the prior art devices. The failures occur somewhat randomly. They occur during autoclaving, immediately after cooling,during storage in the plant, prior to use or at the time of use. A sealed bottle at room temperature will, at times, fail when the temperature drops, increasing the vacuum. Failure may also occur after the blood sample is inserted. The diaphragm has a tendency to depress when a hypodermic needle is penetrating the diaphragm to introduce a sample, thus adding to the problem.
Additionally, there is also a tendency for extraneous micro-organisms (contamination) to lodge between the diaphragm and cap.
It is, therefore, an object of theinvention to provide a cap assembly for biological containers which avoids the limitations and disadvantages of prior art systems.
It is another object of the invention to provide a symmetrical grommet which simplifies assembling the cap assembly.
It is still another object of the invention to provide a reliable cap assembly;
It is yet another object of the invention to provide a cap assembly which eliminates thedanger of a grommet implosion where the containers contain a vacuum.
lt isstill another object of the invention .toprovide a depression for facilitating the entry of a needle into and through the'grommet,
It is 'still another object of the invention to provide a cap assembly which eliminates the danger of the cap blowing during autoclaving. e i
The novel features that are considered characteristic of the invention are set forth in the appended claims; the the invention itself, however, both as to its organization and method ofoperation, together with ad ditional objects and advantages thereof, will best be unmeans in the grommet ofa cap assembly, in the form of derstood from the following description of a specific embodiment when read in conjunction with the accompanying drawings, in which:
FIG. 1 is a section of a closure and container;
, FIG. 2 is a section of the closure; and
FIG. 3 is a section of the closure.
Referring to FIG. 1 there is shown a biological c'ontainer 10 with a cap assembly embodying the principles of the invention. The cap assembly includes a'cap 12 and a rubber, or other resilient material, grommet 13.
The cap 12 is made from a plastic or a metal stamping. It is a screw-on cap having threads complementing the threads of the container 10.
The cap 12 also includes a central aperture 14 in which the grommet 13 is positioned.
The grommet 13 has a pair of like-sized spaced disc portions 16 and 17 joined by a reduced diameter portion 18. The disc portion 17 also includes a recess 19. The grommet 13 is self-sealingwhen punctured by a needle.
Typically, as the cap is screwed on the container the disc portion 17 is compressed between the cap and the top of the container forming a seal. Also, typically, the container is sealed at high temperature. The vacuum created at cooling tends to suck the grommet in. This tendency is depicted by the central depression 21 in the grommet. See FIG. 2.
Note that the disc portion 17 tends to stretch and move that portion forming theseal toward the center of the container. This is a very common occurrence with rubber seals subjected to tension in a direction tending An important consideration, based on experimental data and observation, is that the disc diameter be at least 1.2 times the diameter of the aperture. A circular apertureis illustrated. For other shapedapertures, the dimensional ratio of at least 1.2 is. measured across the aperture along a common axis, i.e., colinearly. For added reliability, the disc diameter should be 1.5 times the diameter of the aperture.
The added security of the 1.5 diameter comes into play when the grommet is punctured by a needle. See FIG. 3. The needle imparts an added force in the same direction as the suction force. Here, too, if the annulus is notwide enough, the grommet will be pushed into the container. I
In the FIG. 1 illustration,.the .disc portions are the same ,size. This symmetry simplifies assembly as the grommet can be insertedwith either disc in either position. Preferably, the recess is in the container, however.
The recess 19 reduces the amountof rubber a needle needs to penetrate to enter the container. This reduces the time needed necessary to pierce the grommet, thus further reducing the vulnerability of the grommet.
The invention is similar to that described in US. Pat. No. 3,499,568, though it is clear that the patented device is different in the following respect. It is, in fact, a stopper which fits intothe bottle. The patented clo sure is assembled when the cap istightened. The upper part is only slightly larger than the central opening and very thin, and not capable of resisting being sucked in, in the absence of the stopper. The metal protective cap appears to be an essential function part of the system and the discussion centers about the use of Agar culture medium, which is typically prepared aseptically.
In summary, the cap assembly just described provides a reliable-biological container and avoids some of the most serious problems associated with prior art concepts.
The various features and advantages of the invention arethought to be clear from the foregoing description. Various other features and advantages not specifically enumerated will undoubtedly occur to those versed in the art, as likewise will many variations and modifications of the preferred embodiment illustrated, all of which may be achieved without departing from the spirit and scope of the invention as defined by the following claims:
1. A cap assembly for a biological culture container having an opening with a marginal edge and means for receiving a threaded cap comprising;
a threaded cap with flat interior and exterior surfaces through which an aperture is defined; and
a grommet made from a'self sealing elastomer with spaced upper and lower disc portions joined by a portion configured to fit into the aperture, the upper disc being dimensioned to be at least 1.2 times the colinear dimensions of the aperture, the grommet is secured to the cap with the upper and lower disc portions in contact with the exterior and interior flat surfaces of the cap, respectively.
2. In a biological culture a container comprising a bottle, a cap assembly for said bottle and culture under a partial vacuum in said bottle, said improvement comprising a cap assembly comprising:
a threaded cap fitted to a complementary threaded opening in the bottle, said cap having flat interior and exterior surfaces through which an aperture is defined; and
a grommet made from a self sealing elastomer with spaced upper andlower disc portions joined by a portion configured to fit into the aperture, the upper disc being dimensioned to be at least 1.2 times the colinear dimensions of the aperture, the grommet is secured to the cap with the upper and lower disc portions in contact with the exterior and interior flat surfaces of the cap, respectively.
3. A cap assembly as defined in'claim 2, wherein said disc portions are the same size.