Improved liquid-tight fastener, especially for cans

Abstract

 This invention relates to an improved can fastener which comprises the can filling port (1), a cylindrical cap (3) provided upperly with a sealing surface and with an annular projection, an O-ring (4) and a ring nut (2). The cap (3) is inserted into the can filling port (1) and the ring nut (2) is then screwed over the filling port (1) after positioning the O-ring (4) at the end of the port.

Description

[0001] This invention relates to an improved liquid-tight fastener for cans, which comprises the can filling port, a cap provided upperly with a sealing surface and an annular projection, and finally a ring nut.

[0002] A liquid-tight seal must be able to be attained even with cans produced by economical moulding means, i.e. starting from a plastics tube which is hot-deformed with compressed air in a suitable mould, until it takes the form of the mould. The resultant filling ports have fairly thin walls, an irregular thread and a high tendency to liquid loss through the fastener, when relatively low pressures are exceeded.

[0003] This drawback becomes worse if it is necessary to make a threaded connection through the cap of a can produced as described, even if the cap is made thicker.

[0004] I have now found that the aforesaid drawbacks can be completely overcome by using a cap provided upperly with a sealing surface, and with an annular projection; the cap is inserted into the can filling port and a ring nut is then screwed over the filling port after positioning an 0-ring at the end of the port. The 0-ring is preferably of nylon. I have also found that by adopting a circular line of contact between the upper parts of the cap and the ring nut, the seal is improved even if vibration is present.

[0005] I have also found that a perfect seal is obtained if, in particular, the lower part of the cap instead of being cylindrical is slightly conical with a vertex angle of less than 10⁰ in the direction of the can interior.

[0006] The ring nut and cap can be of suitable thermoplastic material, for example nylon, or can be of metal.

[0007] The invention is further illustrated by way of non-limiting example in the accompanying figure in which the reference numeral 1 indicates the can filling port, 2 the ring nut, 3 the cap, 4 the 0-ring, 5 and 6 the threaded connectors, which are however extraneous to the invention.

[0008] The filling port has been designed for the simultaneous patent application in the name of the present applicant entitled: "Containers for distributors of liquids for spraying on to hay and other agricultural products", and for this reason ¼" male threaded connectors are shown for the compressed air 5 and for the pressurised liquid 6.

Claims

1. An improved liquid-tight can fastener, comprising: a can filling port; a cap inserted into the port and provided upperly with a sealing surface and with an annular projection; an 0-ring disposed on the end of the port; and a ring nut screwed on to the port.

2. A fastener as claimed in claim 1, wherein a circular contact is used between the cap and ring nut.

3. A fastener as claimed in claim 1 or 2, wherein the lower part of the cap is slightly conical, with the angle at the vertex in the direction of the can interior being less than 10°,

4. A fastener as claimed in one of the preceding claims, wherein one or more liquid-tight threaded connectors are connected to the cap.

5. A fastener as described and illustrated on the drawing.

Drawing