WO1994002376A1 - Threaded plug - Google Patents

Abstract

The invention relates to a threaded plug (10) with an outside diameter of 100 mm or more for large containers, especially large pallet containers with a capacity of, for example, 1000 l, intended for the transport of gassing or outgassing substances. In order to prevent the undesirable formation of internal pressure in the container, there is an aperture (16) with an outgassing device (24) in the middle of the disc-shaped top (12) of the threaded plug (10) which is designed in such a way that it is impossible for a higher vapour pressure than 0.3 bar to form in the gas phase above the fluid content.

Description

 SCREW CAP

The invention relates to a screw cap with a disk-shaped upper part and a flange edge which adjoins its outer circumference and extends at right angles thereto and has an internal thread as a closure cap for a large-volume container, which is intended in particular for the storage and transport of gassing or degassing filling goods.

Such screw caps are e.g. for large-volume pallet containers with a filling volume of e.g. 600 1, 800 1, 1000 1 or more as well as for industrial screw-top L-ring drums with a filling volume of e.g. 60 1 to 220 1 used.

When using certain filling materials which are exposed to special loads during transport due to vibrating movements or when stored outdoors (e.g. sunshine and temperature fluctuations) and / or generally tend to degassing, a disadvantageous internal pressure (overpressure or underpressure) can occur Build up the container. It is therefore desirable to avoid such an internal pressure build-up.

It is an object of the present invention to provide a screw cap - in particular for large containers - with suitable means which prevents such pressure build-up.

This object is achieved in that, in the case of a screw cap with an outer diameter of 100 mm or more, an opening is provided centrally in the disk-shaped upper part of the screw cap, into which an degassing device is inserted. By means of the a pressure build-up or a vacuum formation inside the container is definitely avoided. According to the invention, the degassing device is designed such that no vapor pressure higher than 0.3 bar can build up in the gas phase or in the free space above the liquid content.

In a preferred embodiment, an opening or a bung hole with thread is provided centrally in the disk-shaped upper part of the screw cap for inserting a further screw cap or bung plug with a correspondingly smaller diameter (for example 2 "), the additional bung plug having the degassing device Degassing device can be designed as a one-way degassing device for internal overpressure degassing from the inside out. This prevents the build-up of an internal overpressure that could lead to permanent deformation or bulging of the container. On the other hand, rainwater that may have accumulated in the bung housing cannot Such an internal overpressure degassing device can be designed, for example, in the form of a rubber mushroom nipple (venting plug made of silicone rubber) pressed into a hole in the bung plug.

In another embodiment of the invention it is provided that the degassing device is designed as a two-way degassing device for internal positive pressure degassing and for preventing vacuum formation within the container. With this design of the degassing device, it is additionally avoided that a possible negative pressure in the container can lead to disadvantageous indentations of the container wall or depressions of the upper floor. The screw cap with two-way degassing device device is useful, for example, for containers that are filled with hot contents and in which a vacuum could form by cooling the contents without venting the container. Even when the product is removed from the bottom valve, an air outlet (ventilation) via the two-way degassing device in the screw cap of the filler opening ensures a uniform outlet without annoying gurgling and without creating a vacuum inside the container.

In a further embodiment of the invention it is provided that the degassing device itself is also designed as a threaded screw plug of smaller diameter and is arranged in the center of the bung plug. For example, the screw cap be designed for a bung opening of 220 mm of the large container, then the bung plug is a 2 "bung plug and the degassing device, for example a permeable degassing foil, a porous sintered metal or plastic fiber plug, is in a 3/4" thread by means of a holding cup -Screw plug attached. In the case of a screw cap for a 150 mm bung opening, the bung plug can again have the same size or a size of 1 1/2 "and the threaded screw plug 1/2".

If necessary, it is possible to replace only the small threaded screw plug with the degassing device. If the screw cap is used for non-gassing fillers or if a gas-tight seal is required, all that is required is to unscrew the small threaded screw plug and replace it with a blind plug.

So that the degassing device in the inner bung plug itself is protected against rainwater on the one hand and is secured against unauthorized manipulation or contamination on the other hand provided that the additional bung plug is completely covered with a sealing cap.

Since the large screw cap itself is screwed onto a bung neck of the large container (e.g. in a bung), there is a risk of rainwater collecting in the bung housing and this e.g. if there is negative pressure in the container, it is drawn into the container. This disadvantageous effect is eliminated in a simple and advantageous manner in that one or more small bores or openings are made in the flange edge on the outer edge of the screw cover, for example in the transition region from the flange edge to the disk-shaped upper part, but below the screw cover seal and essentially above the thread . As a result, air, but no rainwater, may then be drawn into the container. This measure becomes particularly important if the degassing device is designed for one-way degassing (internal pressure) or is completely unscrewed and e.g. is replaced by a blind plug.

The invention is explained and described in more detail below with reference to an embodiment shown in the drawings. Show it:

Figure 1 shows a screw cap according to the invention with unscrewed bung plug in a side view with partial section, Figure 2 is a plan view of the screw cap acc.

1 and 3 show an enlarged illustration of the screw cover according to FIG. 1 with the bung plug screwed out in its individual parts. The reference number 10 in FIG. 1 denotes a screw cap for a large container according to the invention. The screw cap 10 is initially characterized by its size, which is 100 mm or more, but is smaller than 400 mm. This screw cap has nothing to do with even larger known screw caps for cover drums such as mash drums, the diameter of which can still be over 400 mm.

As also shown in FIG. 2, the screw cap 10 essentially consists of a flat, disc-shaped upper part 12 and an adjoining flange 14 with an internal thread which extends essentially at right angles thereto. The internal thread has at least three circumferential load-bearing threads. For stiffening and for a better fit of the screw cap, a corresponding inner flange 32 of almost the same length as the outer flange is formed on the inside parallel to the thread-carrying outer flange 14.

A smaller screw cap according to the invention is e.g. manufactured in a size of approx. 190 mm outside diameter (for a 150 mm bung hole), another somewhat larger screw cap has an outside diameter of approx. 260 mm (for a 220 mm bung hole).

As can be seen more clearly in FIG. 3, a bung hole 16 (diameter approx. 56 mm) with a bung hole connector 18 and an internal thread formed therein is formed centrally in the disk-shaped upper part 12 of the screw cap 10. In the bung hole 16 or in the internal thread of the bung hole connector 18, a bung plug 20 is inserted with the appropriate diameter and sealed gas and liquid-tight by means of a seal.

The bung 18 is preferably countersunk in a bung housing 22 such that the one used The plug 20 is essentially flush with the disc-shaped upper part 12 of the screw cap 10.

The plug 20 has a degassing device 24 in the center. The degassing device 24 can either be designed as a one-way degassing device for internal positive pressure degassing from the inside out or as a two-way degassing device. The two-way degassing device also prevents possible vacuum formation within the container. Around the plug 20 against unauthorized opening or the penetration of e.g. To protect rainwater in the degassing device, a sealing cap 26 is also pressed onto the bung 20 or the bung 18, which can only be removed from the bung by destruction or tearing.

In Fig. 3, the degassing device is shown in its screwed apart form (exploded view) with its individual parts. The bung plug 20 is provided with a sealing ring 34 and screwed into the bung hole 18. A bore 36 with an internal thread is made centrally in the bung plug 20, into which the actual degassing plug 40 (small threaded screw plug) provided with a sealing ring 38 is screwed.

The degassing plug 40 in turn has a bore 42 into which a pereable degassing film 44 is inserted and fixed by means of a pressed-in holding body 46 or holding ring. Instead of the degassing film, as mentioned, depending on the degassing behavior of the liquid filled in, a correspondingly gas-permeable but liquid-retaining porous body, for example made of sintered metal, sintered ceramic, fabric structure, parallel plastic Fibers or the like are used. If necessary, only the small degassing plug 40 needs to be replaced; it could also be replaced by a corresponding gastight blind plug. For the user, this embodiment of the screw cap according to the invention offers great variation possibilities.

For a special case, e.g. in the event of overheating, pallet containers or large-volume barrels for liquid fillers must be able to release a sufficient amount of steam to prevent the packaging container from bursting under the influence of fire.

For this purpose, it is provided that the bung plug 20 has a small central bore (without thread) of approximately 6.5 mm in diameter with an inwardly projecting latching lug. A stiff mushroom-like insert made of plastic (e.g. polyethylene or polypropylene) is inserted into the hole from above (from the outside), which is provided with an O-ring made of rubber on the underside of the mushroom head and seals against the surface of the plug.

The mushroom-like insert engages behind the locking lug in the bore and seals the bore against an internal overpressure (only one-way degassing from the inside to the outside). According to a special feature of the invention, the mushroom-like use as a pressure relief device is designed so that it only or at the earliest at an internal pressure of 0.25 kPA (0.25 bar), but at the latest at an pressure of 0.65 kPa ( 0.65 bar) opens and the steam pressure is released. The preferred opening range is between 0.35 to 0.5 kPa.

To prevent rainwater from being sucked in from the bunghole recess of the large container - in the event that the degassing device should, for certain reasons, only be designed as a one-way degassing device. e.g. after a possible vacuum in the container - is expediently made at least a small bore 30 of approximately 2 to 5 mm on the outer edge of the screw cap 10 approximately in the transition region from the outer flange edge 14 to the disk-shaped upper part 12 but below the screw cap seal 28, through which If necessary, air can be sucked in instead of rainwater. In principle, the bore 30 could of course also be designed as a slot in the flange edge 14.

Claims

EXPECTATIONS 1.) screw cap with a disc-shaped upper part and a flange edge which adjoins its outer circumference and extends at right angles thereto and has an internal thread as a closure cap for a large-volume container, which is provided in particular for the storage and transport of gassing or degassing fillings, characterized in that that the outer diameter of the screw cap (10) is at least 100 mm or more, and an opening (16) is provided centrally in the disc-shaped upper part (12), in which a degassing device (24) is inserted. 2.) Screw cap according to claim 1, characterized in that in the disc-shaped upper part (12) of the screw cap (10) an opening or a bung hole (16) with thread for inserting a further screw cap or bung plug (20) with corre sp A smaller diameter is provided, the additional plug (20) being equipped with the degassing device (24). 3.) screw cap according to claim 1 or 2, characterized in that the degassing device (24) is designed as a one-way degassing device for internal positive pressure degassing (from the inside to the outside). 4.) screw cap according to claim 1, 2 or 3, characterized in that the degassing device (24) is designed in the form of a mushroom-shaped plastic insert with rubber O-ring seal as a pressure relief device, which at the earliest at an internal vapor pressure of 0.25 kPa ( 0.25 bar), preferably at about 0.35 kPa to 0.5 kPa, but at the latest at an internal vapor pressure of 0.65 kPa (0.65 bar). 5.) Screw cap according to claim 1 or 2, so that the degassing device (24) is designed as a two-way degassing device for internal overpressure degassing and for preventing vacuum formation within the container. 6.) Screw cap according to claim 1, 2, 3, 4 or 5, d a d u r c h g e k e n n e e c h n e t that the degassing device (24) itself is also designed as a threaded screw plug (32) of smaller diameter and is arranged centrally in the bung plug (20). 7.) screw cap according to one of the preceding claims 1 to 6, d a d u r c h g e k e n n z e i c h n e t that the additional bung plug (20) is covered with a sealing cap (26). 8.) screw cap according to one of the preceding claims 1 to 7, characterized in that on its outer edge approximately in the transition region from the flange edge (14) to the disc-shaped upper part (12) but below the screw cap seal (28) and at least one small bore (30) is formed essentially above the thread.