BACKGROUND ART Jars of this kind are usually composed of glass and prior forms of bungs therefor have comprised solid plugs of rubber, or similar material, within which metal adaptors for connection of lines are embedded. Good sealing under different degrees of vacuum have not always been maintained, and chipping of the glass jar by impaction with the metal adaptors has occurred. A common function of the jars is to trap aspirated fluids, or blood, flowing in a suction line inserted in a patient during surgical operations. Reliable operation of the jar and bung, and facility for quick change-over to a fresh jar, are of prime importance regardless of the operating vacuum, which may be varied in service. it is a chief object of the invention to provide a bung for a collection jar which is reliable in operation under all operating vacuums, and is relatively inexpensive.

DISCLOSURE OF INVENTION In accordance with a general form of the invention there is provided a bung for a collection jar moulded in shell-form from plastics material comprising an outwardly domed top, a peripheral skirt depending from said top, a circumferential recess in the outer face of said skirt, and resilient O-ring accommodated within said recess, the moulding and shaping of said domed top and said skirt being such that with internal vacuum in said jar the domed top becomes depressed to flex said skirt outwardly against the jar to increase sealing between the jar and the bung.

BRIEF DESCRIPTION OF DRAWINGS The invention will be described in more detail with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of a typical jar to be utilised with the bung of this invention;

Fig. 2 shows in exploded perspective, and part^^RE - c...π

section, a first embodiment of the bung;

Fig. 3 shows in side elevation a second embodiment o the bung being entered into a jar shown in fragmentary section; and, Fig. 4 shows the bung of the second embodiment in it fully inserted position within the jar.

BEST MODE OF CARRYING OUT THE INVENTION A jar 1 designed for use with the bung of the invention is shown in Fig. 1. Preferably it is composed of transparent polycarbonate and has a downwardly tapered wall with an enlarged diameter mouth 3 connected to the wall 2 by a shoulder 4. The mouth 3 has an internal annular wall 5 which may be slightly downwardly converging. In its application .as a trap jar for aspirated fluids during a surgical operation, the jar 1 will be conveniently located near the patient and may include a wedge-shaped key 6 engageable within a wall bracket for support of the jar. Th key 6 is preferably integrally formed with the exterior of the wall 2. A graduated scale 7 may be embossed on the oute surface of the wall 2.

A first form of bung 8 shown in Fig. 2 has a body 9 of shell-form composed of thermoplastic material provided with a top 10 on which is integrally formed a twisting handl 11 through which protrudes an inlet adaptor 12 terminating a its lower end in an anti-splash tube 13. It is important that liquids drawn into the jar are not drawn away via the connecting vacuum line, and splashes of incoming liquids which could be drawn away are avoided through the tube 13 directing such liquid against the inner wall 2 of the jar 1. A split-cylindrical housing 14 for a float valve 15 held therein by a retaining disc 21 communicates through the twisting handle 11 with an orifice 16 for a vacuum line (not shown) . The disc 21 is a snap-on fit on the end of the housing 14. An annular skirt 17 depends peripherally from the top 10 and is provided with an annular peripheral slot 1 in its outer wall. The skirt 17 also terminates externally in a small annular groove 17A adjacent its lower end 19 to render the region of the skirt 17 near its lower end 19 more pliable to enable it to conform under reduced pressure wifefe-i--*

^'

the jar 1 to any irregularities in the internal surface in the mouth 3 of the jar 1 and thus achieve better-sealing. The moulding and shaping of both the domed top 10 and the skirt 17 will contribute to the improved seal by causing outward flexing of the skirt 17 against the mouth 3 of the jar 1. In one respect this is achievable by downwardly tapering the skirt, as shown in Fig. 2, and moulding with a resilient but reasonably stiff thermoplastic material, such as antistatic polypropelene. A diametral reinforcing rib

**> (not shown) may be incorporated in the underside of the dome top 10 to ensure against flexing of the skirt 17 at too low vacuum.

A resilient O-ring 20, serving as a primary seal, is accommodated within the annular groove 18. When in use the bung 8 is pressed into the mouth 3 to engage the primary sea of the O-ring 20 and tubing from the patient is attached to the inlet adaptor 12 and a vacuum line inserted into the orifice 16. The primary seal will be adequate for low vacuums, and when higher vacuums are applied the skirt 17 will automatically flex to provide a secondary seal. As the jar 1 fills with liquid the float 15 will rise until its valve head 22 engages a valve seat (not shown) internally surrounding the orifice 16 to close the suction line. By twisting handle 11 the bung 8 may be withdrawn and quickly fitted onto the mouth 3 of a fresh jar 1.

Under conditions of some high vacuums difficulty, sufficient to create a delay in change-over, can arise in removing the bung 8 from a full jar 1.

ALTERNATIVE EMBODIMENT According to a second embodiment of the present invention, the annular groove 18 is composed of a recess 18A formed with two annular juxtaposed grooves 23 and 24. Preferably these two grooves 23 and 24 are separated by a downwardly inclined ramp 25. Furthermore, the uppermost groove 23; i.e., the groove closer to the top 10 is formed o an annulus of greater diameter than that of the groove 24.

Fig. 3 shows the bung 8 being entered into the open mouth 3 of the jar 1 with an O-ring 20A located in the lowermost groove 24. The bung 8 may be forceably introdi

into the mouth 3 of the jar 1, or placed just within the mouth 3 so that with evacuation of the interior of the jar 1 the bung 8 will be drawn down the tapering wall 5 onto the shoulder 4 inside the mouth 3 to the position shown in Fig. 4. In either instance friction between the O-ring 20A and the tapering inner wall 5 will cause the O-ring 20A to ride up and over the ramp 25 to become located within the groove 23. Being now in an annular groove of larger internal diameter than previously, the O-ring 20A will be pressed against the wall 5 with greater pressure. Furthermore, as previously described the domed top 10 of the bung 8 will be caused to flatten due to the reduced pressure within the jar

I to further increase the sealing pressure through the O-rin 20A. Also, the lower end 19 of the skirt 17 will be caused to press against the internal wall 5 of the mouth 13.

When the bung 8 is required to be removed from the jar 1 finger pressure will be applied to the twisting handle

II which will initially cause the O-ring 20A to pass down th ramp 25 into the annular groove 24 of smaller diameter. Accordingly, the sealing pressure between the bung 8 and the jar 1 will be reduced to facilitate removal of the bung 8 from the jar 1.

A preferred embodiment has been described in the foregoing passages but it should be understood that other forms, refinements and modifications are feasible within the scope of this invention.