EP0650446B1 - 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

The invention relates to a screw cap with a disk-shaped upper part and a flange edge which adjoins the 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 filling goods, centered in a degassing device is used in the upper part.
Screw caps of this type are used, for example, for large-volume pallet containers with a filling volume of, for example, 600 l, 800 l, 1000 l or more, and also for screw-lid L-ring drums with a filling volume of, for example, 60 l to 220 l.
When using certain filling materials that 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 build up in the container. It is therefore desirable to avoid such an internal pressure build-up.
From EP-A-0079025 a screw cap with a central degassing device is known which has a sealing washer which can be moved up and down in a valve space formed between the upper and lower parts of the housing. The gas passageway around the disc is open, so that this device is already effective at zero response pressure. In the tilted position or head position, the pane should lie in front of the outer gas passage opening and seal the container securely.

It is an object of the present invention to provide a screw cap with degassing device for special purposes - in particular for large containers or large container openings - with suitable means, which prevents an undesirable build-up of pressure.
This object is achieved in that the outer diameter of the screw cap is at least 100 mm, and centrally in the disc-shaped upper part of the screw cap an opening or a bung hole with thread for inserting another screw cap or bung plug with a correspondingly smaller diameter of z. B. about 50.8 mm (= 2 inches) is provided, the additional plug or the additional screw cap is equipped with the degassing device. By means of the degassing device used in the further bung plugs, pressure build-up or a vacuum formation in the interior of the container is reliably avoided. The degassing device can be designed such that no vapor pressure higher than about 0.3 kPa (0.3 bar) can build up in the gas phase or in the free space above the liquid content.
The degassing device can be designed as a one-way degassing device for internal positive pressure degassing from the inside to the outside. As a result, the build-up of an internal overpressure is avoided, which could lead to permanent deformation or bulging of the container. In such an embodiment variant, the degassing device is advantageously designed in the form of a self-sealing rubber mushroom nipple (venting plug made of silicone rubber) pressed into a hole in the bung plug or a mushroom-shaped plastic insert with a rubber ring seal as overpressure protection, which at the earliest at an internal vapor pressure from 0.25 kPa (0.25 bar), preferably at approx. 0.35 kPa (0.35 bar) to 0.5 kPa (0.5 bar), but at the latest at an internal vapor pressure of 0.65 kPa ( 0.65 bar) opens.
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. In this embodiment 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 is e.g. B. useful for containers that are filled with hot contents and in which a vacuum could form without cooling the container by cooling the contents. Even when filling product from the bottom valve z. B. a pallet container is caused by an air inlet or ventilation via the two-way degassing device in the screw cap of the filling opening, a uniform outlet without annoying gurgling and without 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. So the screw cap z. B. designed for a bung opening of 220 mm of a large container, then the bung is a 2 "bung (= approx. 50.8 mm) and the degassing device, e.g. B. a permeable degassing foil, a porous sintered metal or a plastic fiber plug is attached by means of a holding cup in a 3/4 "threaded screw plug (= approx. 19.05 mm). With a screw cap for a 150 mm bung opening, the The plug has the same size or a size of approx. 38.1 mm (= 1 1/2 ") and the threaded screw plug approx. 12.7 mm (= 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.
In a special embodiment, the degassing device is designed in such a way that in the gas phase or in the free space above the liquid content no internal pressure higher than 0.3 kPa (0.3 bar) can be built up. This version, in which there is no constant degassing, but only the specified minimum pressure has to be reached in order to open the degassing device, is used in particular when storing dangerous liquid filling goods as a safeguard against excessive pressures, e.g. B. can prevent a bursting (bursting) of the container with excessive heating in the event of a local fire.

So that the degassing device in the inner bung plug itself is protected on the one hand against rain water and on the other hand is secured against unauthorized manipulation or contamination 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 (eg in a bung barrel) countersunk into a bung housing, there may be a risk of rainwater in the
Sheet pile housing accumulates and this is pulled inwards into the container, for example if there is negative pressure in 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 replaced, for example, by a blind plug.

Figur 1

einen erfindungsgemäßen Schraubdeckel mit herausgeschraubtem Spundstopfen in Seitenansicht mit Teilschnitt,

Figur 2

eine Draufsicht auf den Schraubdeckel gem. Fig. 1 und

Figur 3

eine vergrößerte Darstellung des Schraubdeckels gemäß Fig. 1 mit herausgeschraubtem Spundstopfen in dessen Einzelteilen.

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

Figure 1

a screw cap according to the invention with unscrewed bung plug in side view with partial section,

Figure 2

a top view of the screw cap acc. Fig. 1 and

Figure 3

an enlarged view of the screw cap of FIG. 1 with unscrewed bung plug in its individual parts.

The reference numeral 10 in Figure 1, a screw according to the invention is designated for a large container. The screw cap 10 is initially characterized by its size, which is 100 mm or more, but is less than 400 mm. This screw cap has nothing to do with even larger known screw caps for lid drums such as mash kegs, 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 manufactured, for example, in a size of approximately 190 mm outside diameter (for a 150 mm bung hole), another somewhat larger screw cap has an outside diameter of approximately 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 bung hole connector 18 and internal thread formed therein is formed centrally in the disc-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 used as a one-way degassing device
Internal pressure degassing from the inside to the outside or as a two-way degassing device. The two-way degassing device also prevents possible vacuum formation within the container. In order to protect the bung 20 against unauthorized opening or the ingress of, for example, rainwater into 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 unscrewed 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 in the center of the plug 20, into which the degassing plug 40 (small threaded screw plug) provided with a sealing ring 38 is screwed.
The degassing stopper 40 in turn has a bore 42 into which a permeable degassing foil 44 is inserted and fixed by means of a pressed-in holding body 46 or holding ring. Instead of the degassing film, a correspondingly gas-permeable but liquid-retaining porous body, for example made of sintered metal, sintered ceramic, fabric structure, and parallel plastic fibers, can be used, as mentioned, depending on the degassing behavior of the respectively filled liquid or similar be used. If necessary, only the small degassing plug 40 needs to be replaced; it could also be replaced by an appropriate gastight blind plug. For the user, this embodiment of the screw cap according to the invention offers great variation possibilities.

In a special case, for example in the event of overheating, pallet containers or large-volume barrels for liquid fillers must be able to release a sufficient amount of steam in order to prevent the packaging container from bursting under the action of fire.
For this purpose, it is provided that the bung plug 20 has a small bore (without thread) with a diameter of approximately 6.5 mm in the center with a locking lug projecting inwards. A rigid mushroom-shaped 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 sheet piling of the bulk container - in the event that the degassing device is to be designed only as a one-way degassing device for certain reasons, 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 (8)

1. A screw top (10) having a disc-shaped upper part (12) and a flanged edge (14) adjoining the outer circumference thereof and extending at right angles thereto and having an internal thread as a closure cap for a large-volume container provided in particular for the storage and transportation of gas-emitting and gas-releasing fillings, wherein a degassing device (24) is inserted centrally into the upper part (12), characterised in that the outer diameter of the screw top (10) is at least 100 mm, and a threaded opening or bunghole (16) for insertion of a further screw top or stopper (20) with a correspondingly smaller diameter is provided centrally in the disc-shaped upper part (12) of the screw top (10), the additional stopper (20) or the further screw top being provided with the degassing device (24).
2. A screw top according to claim 1, characterised in that the degassing device (24) is formed as a one-way degassing device for internal excess-pressure degassing (from the inside to the outside).
3. A screw top according to claim 1 or 2, characterised in that the degassing device (24) is in the form of a mushroom-shaped plastics insert with a rubber O-ring seal as an excess-pressure safety device, opening at the earliest under internal vapour pressure of 0.25 kPa (0.25 bar), preferably approximately 0.35 kPa to 0.5 kPa, but at the latest under internal vapour pressure of 0.65 kPa (0.65 bar).
4. A screw top according to claim 1, characterised in that the degassing device (24) is formed as a two-way degassing device for internal excess-pressure degassing and for preventing vacuum formation inside the container.
5. A screw top according to claim 1, 2, 3 or 4, characterised in that the degassing device (24) itself is also formed as a threaded stopper (32) [sic - 40] of relatively small diameter and is arranged centrally in the stopper (20).
6. A screw top according to any one of the preceding claims 2 to 5, characterised in that the additional stopper (20) can be covered by a sealing cap (26).
7. A screw top according to any one of the preceding claims 1 to 6, characterised in that at least one small bore (30) is formed on its outer edge substantially in the transition region between the flanged edge (14) and the disc-shaped upper part (12), but below a screw-top seal (28) and substantially above the thread.
8. A screw top according to any one of the preceding claims 1, 2 or 5, characterised in that the degassing device is designed in such a manner that internal pressure no higher than 0.3 kPa (0.3 bar) can build up in the gas phase or in the space above the liquid contents.

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