A RELIEF VALVE FOR A PRESSURE CONTAINER

Abstract: A valve (1) for a pressure container (4) serving for distributing a liquid, e.g. beer, under pressure of a gas, e.g. CO2. The valve has a valve seat (8) defining a valve axis (27), an elastomeric valve ring (2) placed coaxially to the valve seat with a preferably coaxially embedded reinforcing ring (17) of e.g. metal, a gas passage (7) which is formed between the valve-ring seat (8) and the valve ring (2) when opening the valve (1), and a liquid passage (10) which is formed at the same time through the central opening (13) of the valve ring. The rim (21) of the reinforcing ring (17) is divided into three sectors (24) of a circle with a larger diameter than the opening (25) of the valve seat (8). The circle sectors (24) are again divided by three curved recesses (26). When the pressure in the container (4) exceeds a preselected permissible overpressure, the elastomeric material in the recesses is deformed to such an extent that openings (29) are made for relieving the overpressure. Thus, the valve according to the invention can function as a very efficient relief valve.

Description: A relief valve for a pressure container The invention relates to a valve for a pressure container for distributing a liquid, e.g. beer, under pressure of a gas, e.g. C0 2 , and of the kind which comprises a valve seat defining a valve axis, an elastomeric valve ring placed coaxially to the valve seat with a preferably coaxially embedded reinforcing ring of e.g. metal, a gas passage which is formed between the valve ring seat and the valve ring when opening the valve, and a liquid passage which is formed at the same time through the central opening of the valve ring. Transportable pressure containers are used for distributing beverages, such as beer, to be served in portions in e.g. a restaurant. When the container is to be used, its valve is mounted with a coupling head with connections for a pressure bottle or cartridge containing a pressure gas, normally CO2 , and a barrel tap for drawing the beverage. In the coupling head is a spindle for opening the valve by displacement with a grip. In order to be able to keep the beverage fresh during transportation and storage, the gas pressure must necessarily be maintained, and the valve must therefore always keep completely tight in closed condition. Conventional valve rings are therefore made of elastomeric materials, such as rubber which can be elastically deformed to abut tightly at the gas passage and the liquid passage, respectively, by the load of at least one compression spring. A safe sealing presupposes that the valve ring is acted upon by relatively great forces which the elastomeric material itself hardly can absorb without the ring being buckled, whereby the gas and/or liquid passage will be liable to leak, and the valve ring can be forced out of its position in the valve. The elastomeric material of said conventional valve ring is therefore stiffened by a plate-shaped reinforcing ring of a strong, solid material, for example stainless steel. A binding agent is applied to the ring at the manufacturing and it is cast together with the elastomeric material to an integrated unit. The transportable pressure containers are normally without any danger to the surroundings. The working pressure is only a few bars, and the containers are dimensioned with a large safety margin in relation to this pressure. However, if a container is exposed to intense heat action, which for instance might be the case when a building is burning, the pressure in the container might get so high, that the container will explode whereby persons, who might be nearby, could be hit and seriously injured. As these containers are used for beverages, they can hardly be supplied with special relief valves for blowing off too high a pressure. This is, among other things, due to the fact that an efficient relief valve is a rather complicated mechanism with components and inaccessible corners which make it hard or impossible to clean the relief valve satisfactorily when cleaning the rest of the container. Therefore, there will always be a risk that such relief valves might be origin for development of e.g. cultures of bacteria which might destroy or poison the beverages stored in the container. The conventional valves have a structure implying that the valves, without being dismounted, can be cleaned effectively and safely in the same process as the rest of the container. However, the construction implies, at the same time, that a rising pressure will close the valve tighter. These conventional valves are therefore not in itself able to ensure a container from exploding due to overpressure. The object of the invention is to provide a valve of the kind mentioned in the opening paragraph that has all the advantages of the conventional valves, and is just as easy to clean optimally, and is furthermore constructed to ensure the container from bursting due to a much too high overpressure. The novel and unique features according to the invention whereby this is achieved, is the fact that the outer periphery of the reinforcing ring defines a curve with at least one first section placed at a greater distance from the valve axis than the inner periphery of the valve-ring seat, and at least one second section placed at a smaller distance. When the overpressure in the container reaches a preselected level, the elastomeric part of the valve ring will start being forced out through the valve seat until the reinforcing ring abuts on the valve seat at its first periphery section and prevents the safety ring from being shot out into the room endangering the surroundings . At a sufficiently high overpressure, the reinforcing ring is deformed while the elastomeric material of the valve ring yields at its second periphery section so that an opening for relieving the overpressure in the container is formed between the valve ring and the valve seat. Therefore, the valve according to the invention functions as a very efficient relief valve. To obtain optimum security against the container exploding due to a too high overpressure, the distance between the valve axis and the first section of the periphery curve can be between 0.9 and 1.2 and preferably between 1.0 and 1.1 times the distance between the valve axis and the inner periphery of the valve seat while the distance between the valve axis and the second section can be between 0.75 and 0.95 and preferably between 0.8 and 0.9 times the distance between the valve axis and the inner periphery of the valve seat. In an especially simple and expedient embodiment, the first section of the curve which is defined by the outer periphery of the reinforcing ring can run along a circle and the second section can define a curved recess in the circular outer periphery . In practise, it is an advantage if the outer periphery of the reinforcing ring runs along a number of equally spaced circles that are broken by just as many recesses. In order to be able to blow off a too high overpressure in the container via the openings at the recesses, each of these recesses must span a sufficiently great area, and at the same time the material thickness of the reinforcing ring must not be too thick. It has turned out that the valve ring functions efficiently as relief valve when the greatest breadth of each recess is at least twice as broad as the thickness of the reinforcing ring. The effect is promoted when the recess furthermore is provided with sharp edges as the elastomeric material is cut completely or partly through along these edges . The reinforcing ring can advantageously be shaped as a plate with a bottom and an annular rim. Having this double curved design, the ring is given a great section modulus against axial load so that the ring preliminary is able to force the elastomeric material out through the opening in the valve seat under the action of the overpressure in the container. When the valve ring has a collar facing the valve seat, the annular rim of the reinforcing ring can advantageously be fitted into this collar at a short distance of preferably less than 2 mm from the collar side opposite of the side facing the valve seat so that the elastomeric material in and at each recess attains a thickness so thin and thereby a small section modulus that the material can be deformed to a sufficient extent under the action of the preselected overpressure. The invention will be explained in greater detail below with reference to the drawing, in which Fig. 1 is a cross-sectional side view of a section of a valve according to the invention. Fig. 2 shows a valve ring for the valve shown in fig. 1, Fig. 3 shows the valve ring in fig. 2 seen from below, Fig. 4 is a cross-sectional side view of a section of the valve ring shown in fig. 2 and 3 in loaded condition, and Fig. 5 shows the valve ring in fig. 4 seen from below. Transportable containers are used for distributing beverages, such as beer, cola, soft drinks, and wine, under pressure of C0 2 . However, the containers can also be used for many other liquids, just as the gas can be another than C0 2 . The containers do not have to be transportable, but can just as well be stationary. The valve can be designed as shown, but such valves also have many other designs. The embodiment shown in fig. 1 is therefore only used in the below description to exemplify the invention, and as the structure is known per se, it will only be described in broad outline. The valve consists mainly of a valve body 5 screwed into a connection piece 3 on a pressure container 4, and a riser pipe 6, only fragmentarily shown, which is displaceably fitted in the body. The left side of the figure shows the valve in open position, while the right side shows the valve in closed position. Furthermore, an elastomeric valve ring 2 for opening and closing the valve is placed concentrically to the valve seat 8 in the valve. This valve ring is shown on a larger scale in fig. 2. When the valve is open, as shown in the left side of the figure, there is a gas passage 7 between a valve seat 8 in the valve body 5 and a contact face 9 on the valve ring 2. There is furthermore a liquid passage 10 between a valve plug 11 and a valve-ring seat 12 in the central opening 13 of the valve ring. When the valve is to be closed, as shown in the right side of the figure, the riser pipe 6 is displaced with the valve ring 2 by a first compression spring 14 until the contact face 9 of the valve ring abuts on the valve seat 8. Thereby, the gas passage 7 is closed. At the same time, the valve plug 11 is displaced by a second compression spring 15 to abut on the valve-ring seat 12 so that the liquid passage 10 is also closed. When the container 4 is to be used, its valve 1 is detachably mounted with a coupling head (not shown) with a displaceable, tubular spindle 16, of which the bottom part is seen in fig. 1. The spindle treads with its bottom part on the valve plug 11 and the valve ring 2, which both are removed from their seats 8; 12, so that the valve is opened when the spindle is displaced downwards in the figure by operating a grip (not shown) on the coupling head. The gas is supplied to the valve and the container via the coupling head which, in operation, is connected with a pressure bottle or cartridge containing pressure gas (not shown) . Similarly, the liquid is led out via the valve and the tubular spindle 16 of the coupling head, said spindle is connected with a barrel tap at the place of drawing (not shown) . A first reinforcing ring 17 of e.g. stainless steel is, after having been surface treated with a binding agent, concentrically embedded in the elastomeric material, e.g. vulcanised rubber, of the valve ring 2. A second reinforcing ring 18 of e.g. stainless steel is fitted onto the valve ring 2 partly by being clamped around the elastomeric material of this ring, and partly by being beaded around the inner rim area 19 of the first reinforcing ring 17. Combined the two reinforcing rings 17 and 18 serve for reinforcing the valve ring 2 and absorbing the stress from the spindle 16 of the coupling head when the valve is opened. The first reinforcing ring 17 is shaped as a plate with a bottom 20 and an annular rim 21 extending into a collar 22 on the valve ring 2 at a short distance from the underside of the collar. Fig. 3 shows this reinforcing ring 17 seen from below. A number of transverse openings 23 are made in the ring for creating a break-joint between the parts of the elastomeric material of the valve ring that are on the two sides of the reinforcing ring 17. The rim 21 of the reinforcing ring 17 is divided into three sectors of a circle 24 having a larger diameter than the opening 25 of the valve seat 8. The circle sectors 24 are again separated by three curved recesses 26. When the valve ring 2 is placed in the valve 1, each of these curved recesses 26 are at a shorter distance from the valve axis 27 than the edge 28 of the opening 25 in the valve seat 8. Fig. 4 and 5 are on a larger scale fractional, cross-sectional views of the valve ring 2 in a situation where it is loaded by an overpressure higher than the permissible. At first, the overpressure has forced the main part of the elastomeric collar 22 of the valve ring out through the opening 25 in the valve seat 8 until the circle sectors 24 of the valve ring abut on the underside of the valve seat 8. At the end, the bottom 20 of the valve ring is also shot up through the opening 25 of the valve seat while its rim is stopped by the valve seat so that the valve ring now has the shape shown in fig. 4. As mentioned earlier, there is only a thin layer of elastomeric material under the rim of the valve ring, the material will therefore yield in the recesses 26 under a stress combined by the overpressure in the container and the tension that is generated between the rim of the valve ring and the elastomeric material over the valve seat. Furthermore, the edges of the recesses are sharp and they will therefore at the same time try to cut partly or completely through the elastomeric material in the recesses. All things considered, the result of the above mentioned processes is that the elastomeric material in the recesses is deformed so that openings 29 are made at the recesses through which the gas can flow in the direction indicated by the arrow. Thereby, the overpressure in the container is relieved. At overpressures at a preselected level, the valve according to the invention thereby functions as a very efficient relief valve . In the embodiment described above and shown in the drawing, the valve ring 2 had a second reinforcing ring 18 besides the first reinforcing ring 17, this ring 18 was merely clamped onto the elastomeric part of the valve ring. When the valve ring is deformed, its elastomeric collar 22 will therefore be forced free of the reinforcing ring 18, as shown in fig. 2. It is in this connection to be noted that the functioning of the valve as relief valve do not depend on the presence of the second reinforcing ring 18, and that other embodiments of the valve ring 2 without this reinforcing ring are possible within the scope of the invention. Furthermore, the embodiment of the reinforcing ring 17 as described and shown only serves as an example for illustrating the invention. The outer periphery of the ring can thus be designed in many other ways. Thus, there can be more or less than three recesses, and each recess does not necessarily have to be curved just as the periphery sectors between the recesses do not necessarily have to be circular.

Claims: C A I M S 1. A valve (1) for a pressure container (4) for distributing a liquid, such as beer, under pressure of a gas, such as C0 2 , and of the kind which comprises a valve seat (8) defining a valve axis (27), an elastomeric valve ring (2) placed coaxially to the valve seat with a reinforcing ring (17) of e.g. metal fitted preferably coaxially, a gas passage (7) which is formed between the valve-ring seat (8) and the valve ring (2) when opening the valve (1), and a liquid passage (10) which is formed at the same time through the central opening (13) of the valve ring, characterised in that the outer periphery of the reinforcing ring (17) defines a curve with at least one first section at a greater distance from the valve axis (27) than the inner periphery of the valve-ring seat, and at least one second section at a smaller distance. 2. A valve (1) according to claim 1, characterised in that the distance between the valve axis (27) and the at least one first section of the curve defined by the outer periphery of the reinforcing ring (17) is between 0.9 and 1.2 and preferably between 1.0 and 1.1 times the distance between the valve axis (27) and the inner periphery of the valve seat (8) . 3. A valve (1) according to claim 1 or 2 , characterised in that the distance between the valve axis (27) and the at least one second section of the curve defined by the outer periphery of the reinforcing valve (17) is between 0.75 and 0.95 and preferably between 0.8 and 0.9 times the distance between the valve axis (27) and the inner periphery of the valve seat (8) . 4. A valve (1) according to claim 1, 2, or 3 , characterised in that the at least one first section of the curve defined by the outer periphery of the reinforcing ring (17) runs along a circle, and that the at least one second section defines a recess (26) in the circular outer periphery. j. A valve (1) according to claim 4, characterised in that the greatest breadth of the at least one recess (26) is at least twice the thickness of the reinforcing ring (17). 5. A valve (1) according to claim 4 or 5 , characterised in that the at least one recess (26) is curved. 7. A valve (1) according to each of the claims 4, 5, or 6, characterised in that the at least one recess (26) has sharp edges (29) . 8. A valve (1) according to each of the claims 1 - 7, characterised in that the reinforcing ring (17) is shaped as a plate with a bottom (20) and an annular rim (21) . 9. A valve (1) according to claim 8, and where the valve ring (2) has a collar (22) facing the valve seat (8), characterised in that the annular rim (21) of the reinforcing ring (17) is placed in the collar (22) of the valve ring (2) at a short distance from the collar side opposite of the side facing the valve seat (8) . 10. A valve (1) according to claim 8 or 9 , characterised in that the annular rim (21) of the plate-shaped reinforcing ring (17) is placed in the collar (22) at a distance of less than 2 mm from the collar side opposite of the side facing the valve seat (8) .

Inventors: IPSEN BERNT, WINTHER MORTEN N, IPSEN, BERNT, WINTHER, MORTEN, N.
Applicants: IPSEN BERNT, MICRO MATIC AS, WINTHER MORTEN N, IPSEN, BERNT, MICRO MATIC A/S, WINTHER, MORTEN, N.
Application year: 1998
Main classification: B67D1
IPC codes: B67D1