A valve of this kind is described in EP 0 883 766, arranged at the bottom of a vessel, which is part of a deodorization plant for vegetable oil. In a plant of this kind there is very high temperature, usually of about 250°C.

This puts up extremely high demands on valves, which is to be used in such plants, especially on the seal members of the valves.

The object of the present invention is to provide a valve, which meets the demands being put up for example at a plant of the just defined kind.

According to the invention this object may be obtained by means of a valve of the initially defined kind, which is characterized by - that an E-ring sealing of metal, which in cross-section has at least three branches directed in the same direction, is arranged to seal against at one end said circumferential portion of the valve disc and at the other end said seating member, when the valve disc is in its closed position, - that the valve disc in its closed position, besides through the E-ring seating, has direct contact with the seating member, the E-ring sealing having such axial extension that it comes in contact with both the seating member and the valve disc before said direct contact occurs upon movement of the valve disc from its opened to its closed position, and - that at least one fastening member is arranged to retain the E-ring sealing in either one of the seating member or the valve disc.

By an E-ring sealing in this connection a ring sealing is intended, the cross-section of which has three or more branches, all being directed radially towards or away from the centre of the E-ring sealing. Each branch in said cross-section is formed by an annular flange extending both in the circumferential direction of the ring sealing and radially.

In a preferred embodiment of the invention an E-ring sealing is used, the cross-section of which has only three branches of said kind. Advanta- geously such E-ring sealing may be made of a metal plate ring, which in a cross-section has been bent in a way such that the intermediate of said three branches is formed of a substantially V-or U-shaped central part of the metal plate ring. Alternatively the central part of the metal plate ring may have been folded 180°, seen in the cross-section of the E-ring sealing, so that the intermediate branch is formed by two portions of the metal plate ring, which are in contact with each other. Thus, an E-ring sealing with three branches delimits two annular cavities between the branches respectively, which are open to a radially directed first side of the E-ring sealing and one (or none) annular cavity, which is open to a radially directed (opposite) second side of the E-ring sealing.

In a preferred embodiment of the invention the E-ring sealing is relea- sably connected with either of the seating member and the valve disc. In that way the E-ring sealing may easily be changed, if required.

As earlier said the E-ring sealing is kept in place by means of at least one fastening member. Preferably the E-ring sealing is kept in place by means of several fastening members being evenly distributed round the circumferential portion of the valve disc. The fastening members may be formed in any suitable way. In a preferred embodiment of the invention the fastening members comprise separate holders, e. g. in the form of small plate pieces provided with holes or grooves for screws or the like, which is arranged to releasably retain the holders to one of the seating member or the valve disc. The fastening members are arranged to extend into one of the cavities of the E-ring sealing, preferably the cavity that is open against the said radially directed second side of the E-ring sealing.

For contact between the valve disc and the seating member the valve disc may have a first flange, which extends along the circumferential portion of the valve disc and is directed towards the seating member.

Thus, when the valve disc is in its closed position this first flange is present in direct contact with the seating member. In a preferred embodiment of the invention the valve disc also has a second flange, which extends along and at a distance from the first flange, and with which the second flange the said fastening device are connected, in a preferred way releasably. In an alternative embodiment of the invention the second flange may comprise at least one projection, which is intended to be permanently connected with the same. In this case entire or a part of the E-ring sealing may be arranged to be bend around each such projection, thanks to the flexibility of the E-ring sealing, in order to be releasably connected with the valve disc.

As initially said the E-ring sealing may be arranged at either one of the seating member or the valve disc. In the case the E-ring sealing is arranged at the seating member the valve disc does not need to have any of the said flanges. Instead the seating member may be formed with for example a groove or an edge extending in the circumference direction of the seating member where the E-ring sealing may be arranged. Then, holders of the aforementioned kind may be attached to the seating mem- ber, and to be arranged to hold the E-ring sealing in place. However, in a preferred embodiment of the invention the E-ring sealing is attached to the valve disc and thereby arranged between the first and the second flange.

The above mentioned branches seen in a cross-section of the E-ring sealing may be directed in different directions depending on how a liquid pressure is intended to affect the valve, when this is used and is closed.

For the case the valve is to be arranged in the bottom of a vessel filled with liquid and the valve disc is to be present above the valve seating, the branches of the E-ring sealing is suitably directed away from the centre of the valve disc. Hereby, the pressure from the liquid in the vessel namely can contribute to the sealing of the E-ring sealing against the seating member and the valve disc.

If the valve instead should be arranged so that a liquid pressure would be directed substantially away from the centre of the valve disc and out towards the surrounding portion of the valve disc, it would be suitable to have the branches of the E-ring sealing directed towards the centre of the valve disc.

An E-ring sealing of the kind mentioned above is previously known, e. g. through EP 1 306 589, but as far as known has not previously been used in a valve in the way suggested according to the invention.

The invention is to be further described in the following with reference to the accompanying drawing, in which Fig. 1 diagrammatically shows a valve according to the invention seen in axial section and in its open position, and Fig. 2 shows a part of a valve disc and an E-ring sealing at the circumferential portion of the E-ring sealing.

In figure 1 there is shown a valve 1, which is arranged in the bottom of a vessel 2. The valve 1 is connected with the vessel 2 through a seating member 3. The seating member comprises a first component 4, which is arranged to be fixedly connected to the vessel bottom, e. g. through wel- ding, and a second component 5, which is a part of the valve 1 and is arranged to be releasably connected to the first component 4. Further- more, the valve 1 comprises a valve disc 6, which is arranged to be moved between a closed position and an open position by means of a control member 7. When the valve disc 6 is present in its open position a flow passage P is formed through the same, whereby the liquid may flow out of the vessel 2. The valve disc 6 is supported by a piston rod 8, which is connected with a piston 9 arranged within the control member 7. More- over, the control member 7 has two connections 10 and 11 for a pressure fluid. These connections open in a first space 12 and a second space 13, respectively, on either side of the piston 9. The control member 7 is con- nected with the component 5 of the seating member 3 through a number of supporting elements 14.

In the figure 2 there is shown in axial section an edge portion of the valve disc 6. Underneath, this edge portion has a first annular outer flange 15 and a second annular inner flange 16. The outer flange 15 is arranged to be in contact with the seating member 3 when the valve disc is present in its closed position. Fastening members 17 in the form of small plate pieces, distributed along the inner flange 16, are arranged to be releasably connected with this inner flange 16 by means of fastening elements 18 and retain an E-ring sealing 19 underneath the valve disc 6.

The E-ring sealing 19 is arranged between the outer flange 15 and the inner flange 16.

The E-ring sealing 19 has a first upper branch 20, a second intermediate branch 21 and a third lower branch 22. The intermediate branch 21 com- prise$ two portions, a first portion 21 a and a second portion 21 b. The first portion 21 a connects the intermediate branch 21 with the upper branch 20 and the second portion 21 b connects the intermediate branch 21 with the lower branch 22. Between the branches 20-22 three cavities is for- med. At the radially outer side of the E-ring sealing a first cavity 23 is formed between the upper branch 20 and the intermediate branch 21, and a second cavity 24 is formed between the intermediate branch 21 and the lower branch 22. At the radially inner side of the E-ring sealing a third cavity 25 is formed between the two portions 21a and 21 b of the intermediate branch 21. The fastening members 17 extend into the third cavity 25 and in this way keep the E-ring sealing in place. The upper branch 20 is in contact with the valve disc 6 when the E-ring sealing 19 is in place. The lower branch 22 is arranged to get into contact with the seating member 3 (see figure 1) before the outer flange 15 of the valve disc 6 does, when the valve disc 6 is moved towards its closed position.

The valve described above operates as follows.

When the valve disc 6 is present in its open position an over pressure is present in the space 12 below the piston 9. For closing of the valve disc 6 a pressure fluid is forced into the space 13 above the piston 9 simulta- neously fluid is released out of the space 12, the valve disc 6 being moved downwardly towards the seating member 3 thereby. As can be seen from figure 2, the lower branch of the E-ring sealing first comes into contact with the seating member 3. Then the valve disc 6 moves further against the seating member 3, which results in that the outer flange 15 comes into contact with the seating member 3. In this position of the valve disc 6 its upper branch 20 is pressed by spring force occurred in the E-ring sealing 19 to seal against the valve disc 6, whereas the lower branch 22 is forced to seal against the seal member 3.

A total sealing between the flange 15 and the seating member 3 is not expected, wherefore liquid, which is present in the vessel 2 when the valve is closed, will flow between the outer flange 15 and the seating member 3 in the cavities 23 and 24 of the E-ring sealing. The pressure from the liquid will press the upper branch 20 against the valve disc 6 and the lower branch 22 against the seating member 3 even harder than before and in this way ensure a good sealing between the valve disc 6 and the seating member 3 even at a high liquid level in the vessel 2.