Pressure control device for a beverage container

Abstract

A pressure control device for controlling a pressure in a beverage container comprises a gas filled pressure control chamber enclosed by a wall of the pressure control device. The wall has an inner surface facing the chamber and an outer surface facing away from the chamber, the inner surface and outer surface defining a thickness of the wall. A scavenger material is provided in the pressure control device for capturing gas that enters, during use, into the pressure control chamber. The scavenger material is distributed over the wall thickness with a predetermined concentration from the inner surface towards the outer surface of the wall such that a rate of gas capture by the scavenger material changes over time.

Claims

1. A pressure control device for controlling a pressure in a beverage container, the pressure control device comprising a gas filled pressure control chamber enclosed by a wall of the pressure control device, and a scavenger material provided in the pressure control device for capturing gas that enters, during use, into the pressure control chamber, wherein the wall has an inner surface facing the chamber and an outer surface facing away from the chamber, the inner surface and outer surface defining a thickness of the wall, wherein the scavenger material is distributed over the wall thickness with a predetermined concentration from the inner surface towards the outer surface of the wall such that a rate of gas capture by the scavenger material changes over time.

2. The pressure control device according to claim 1, wherein the scavenger material is distributed over the wall thickness in a varying concentration.

3. The pressure control device according to claim 1, wherein the scavenger material is distributed over the wall thickness in a constant concentration.

4. The pressure control device according to claim 1, wherein the wall is made by injection moulding of an injection mouldable material mixed with the scavenger material.

5. The pressure control device according to claim 4, wherein the injection mouldable material is a material having a limited gas permeability for the gas that enters, during use, into the pressure control chamber.

6. The pressure control device according to claim 4, wherein the injection mouldable material is a thermoplastic material.

7. The pressure control device according to claim 6, wherein the thermoplastic material comprises low-density polyethylene (LDPE) or linear low-density polyethylene (LLDPE).

8. The pressure control device according to claim 1, wherein the wall has at least one movable wall part for operating a mechanism for opening and/or closing a gas supply opening of a gas holder.

9. The pressure control device according to claim 1, wherein a first amount of the scavenger material is provided in the wall in a layer at the inner surface to capture a first amount of the gas that enters, during use, into the pressure control chamber over a first time period, and at least a further amount of the scavenger material provided in the wall behind said layer to capture a further amount of the gas that enters, during use, into the pressure control chamber over a further time period following the first time period.

10. The pressure control device according to claim 1, wherein the predetermined concentration of the scavenger material provided in the wall is a concentration adapted to a surface area to volume ratio of the pressure control chamber.

11. A beverage container provided with a pressure control device in accordance with claim 1.

12. The beverage container according to claim 11, wherein the beverage container contains an effervescent beverage such as a malt based beverage, for example beer, or an apple based beverage, for example cider.

13. The beverage container according to claim 12, wherein the effervescent beverage comprises a malt-based beverage or an apple-based beverage.

14. The beverage container according to claim 13, wherein the effervescent beverage comprises the malt-based beverage, and the malt-based beverage is beer.

15. The beverage container according to claim 13, wherein the effervescent beverage comprises the apple-based beverage, and the apple-based beverage is cider.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a first example scavenger;

(2) FIG. 2 shows a second example scavenger;

(3) FIG. 3A shows a third example scavenger;

(4) FIG. 3B shows a fourth example scavenger;

(5) FIG. 3C shows a fifth example scavenger;

(6) FIG. 4A shows a sixth example scavenger;

(7) FIG. 5A shows a seventh example scavenger; and

(8) FIG. 6 is a graph showing a deviation of piston position over time for three pressure control devices.

DETAILED DESCRIPTION

(9) In the specific embodiment of the pressure control device in accordance with the invention a gas filled pressure control chamber is provided enclosed by an injection moulded wall. The wall comprises at least one movable wall part, i.e., a piston, for operating a mechanism for opening and/or closing a gas supply opening of a gas holder as described in WO2006/091069. For comparative purposes a pressure control device as described in WO2006/091069 as well as a pressure control device having no scavenger material are also provided. The embodiments of the pressure control devices differ from each other in that in the known pressure control devices there is no amount of Ca(OH).sub.2 provided, so that a scavenging reaction of gas does not take place, or an amount of Ca(OH).sub.2 is provided in the pressure control chamber directly exposed to CO.sub.2 gas migrating into the chamber, so that a reaction between the gas and scavenger Ca(OH).sub.2 is unhindered, whereas in the specific embodiment of the pressure control device according to the invention the injection moulded wall is made of a mix of Ca(OH).sub.2 and LDPE in a weight ratio of approximately 40:60, so that the Ca(OH).sub.2 is distributed over the wall thickness in an approximately constant predetermined concentration.

(10) These pressure control devices were tested to compare their ability to maintain an approximately equal control pressure for a longer period of time. For a period of 30 weeks from assembly of the pressure control devices a position of the piston was checked weekly as representative for an actual control pressure in the pressure control chamber. A deviation of the piston position compared to a reference position of the piston (0 mm) at predetermined control pressure was measured in mm's, with a positive value representing an extended position of the piston reflecting a pressure increase in the pressure control chamber and a negative value representing a pressure decrease in the pressure control chamber. The results for each of the pressure control devices is shown in the graph in FIG. 6.

(11) The upper line in the graph is the result of the pressure control device without Ca(OH).sub.2. It demonstrates an almost linear increase in pressure over the 30 weeks, which is due to CO.sub.2 gas migrating into the pressure control chamber. The lower line in the graph is the result of the pressure control device with Ca(OH).sub.2 powder provided in the pressure control chamber. It demonstrates an almost linear decrease in pressure over the 30 weeks, which is due to effectively all CO.sub.2 gas migrating into the pressure control chamber being directly exposed to the Ca(OH).sub.2 powder and reacting therewith, while the control pressure gas in the pressure control chamber leaks from the chamber. The middle line in the graph is the result of the pressure control device according to the present invention with Ca(OH).sub.2 distributed over the wall thickness. It demonstrates an almost constant piston position and thus control pressure in the pressure control chamber over the 30 weeks. This is due to the leak of pressure gas from the pressure control chamber being compensated by an increase in CO.sub.2 in the chamber as the Ca(OH).sub.2 distributed over the wall thickness provides a decreased CO.sub.2 capture rate. At the 20 weeks mark gas in the pressure control chamber was analyzed and showed to comprise approximately 10 vol. % CO.sub.2.

(12) An embodiment of a scavenger 10 for use in a pressure control device according to the invention is shown in FIG. 1 in a perspective view. The scavenger 10 is a solid scavenger including a carrier molded using polypropylene and a solid ring of calcium hydroxide contained within the carrier. The process of manufacturing the scavenger is not practical and dust occurs such that personnel creating the product has to have protective masks and clothing. Another embodiment of a scavenger 20 for use in a pressure control device according to the invention, as shown in FIG. 2 in a cross-sectional perspective view, is made using over molding where the polypropylene has openings therein so that the carbon dioxide is exposed to the compacted calcium hydroxide.

(13) Preferably the creation of these scavengers 10, 20 using calcium hydroxide involves providing a polymeric material with a high permeation rate to carbon dioxide and then have calcium hydroxide material encapsulated in the polymer. This compound then provides a material which can be injection molded to produce solid scavengers.

(14) FIGS. 3A,3B,3C show perspective views of other embodiments of solid scavengers 30A, 30B, 30C, which have various configurations. For example, the solid scavenger 30A shown in FIG. 3A has a ring-type configuration, and the solid scavenger 30B shown in FIG. 3B has a fin-type configuration.

(15) Referring to FIG. 4A, a preferred embodiment of a solid scavenger 40A is shown with the molded compound of the polymeric material in the calcium hydroxide. As is therein shown, there are six rings of material which provide a large surface area which can be contacted by the carbon dioxide and, as a result of the thickness, the carbon dioxide permeates and is absorbed. Also, as shown in FIG. 5A, there is a similar solid scavenger 50A which has ribs interconnecting the circular rings of the molded material. The ideal wall of thickness of the rings is approximately 0.5 millimeters and can be between 0.2 and 0.8 millimeters to obtain better penetration of the carbon dioxide.

(16) For the purpose of clarity and a concise description, features are described herein as part of the same or separate aspects and preferred embodiments thereof, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.