Valve, particularly double-seat valve

Details Valve, particularly double-seat valve Valve, particularly double-seat valve

1999-09-15

2001-05-15

Walton, George L. (Department: 3753)

Fluid handling

With leakage or drip collecting

C137S240000, C137S614180, C251S063500, C251S063600, C251S900000

Reexamination Certificate

active

06230736

ABSTRACT:

The invention relates to a valve with a valve housing and at least one movable valve body cooperating with a valve seat or face, which has at least one sealing groove open to the valve seat or face, in which is placed or placeable a sealing body for sealing the valve body with respect to the valve seat or face.
In the case of valves of this type, they can in particular be single-seat or double-seat aseptic valves, such as are used for the control of flowable products in the chemical and foods sector. They can be constructed as ring main valves, bottom seat valves, angle valves or the like and generally have axially movable valve bodies.
Double-seat valves are more particularly used for the control of flowable products to be kept separated in the brewing, beverages, dairy, foods, pharmaceutical or chemical sectors, particularly in dairy installations for the control and simultaneous separation of milk and cleaning fluid. A double-seat valve has a valve housing, which has a first housing area e.g. connectable to a first pipe, e.g. a product pipe, and a second housing area e.g. connectable to a second pipe, e.g. a cleaning fluid pipe. For the random connection or sealed separation of the housing areas are provided an axially movable, first valve body cooperating with a valve seat and a second valve body cooperating with a valve seat and which is movable axially and relative thereto and in series therewith. The valve bodies define between them a leakage cavity open to the environment of the valve and each valve body has at least one sealing groove open to the associated valve seat, in which is placed or placeable a sealing body for sealing the valve body against the valve seat. The valve bodies are movable in such a way that in a closed position they prevent an overflow of fluid between the housing areas and in an open position permit an overflow, accompanied by a sealing of the leakage cavity. The leakage cavity is more particularly used for the leakage-proof separation of the products, because with sealing problems fluid passes from one or both of the housing areas into the leakage cavity, but not into the other housing area.
Particularly in the indicated use sectors, hygiene and cleanliness, as well as the possibility of a rapid, thorough cleaning of a valve is very important. Particular importance is attached to the fact that no contaminants can be deposited in the valves and/or contaminants can be easily removed. Thus, for cleaning purposes many of these valves can be rinsed through at regular intervals with a cleaning fluid in order to eliminate any contaminants which may have become deposited. Deposits which have not been removed, particularly with dairy products, cosmetics, etc., can aid the formation of germs, so that in unfavourable cases large product batches are contaminatable and therefore rendered unusable. It is generally desired to be able to easily replace and/or clean valves fixed within pipe networks.
Known double-seat valves, such as are disclosed by DE 38 35 944 or EP 711 940, are able to very adequately fulfil many of these requirements, but sometimes there is a tendency to contamination and germ formation.
The problem of the invention is to provide a valve obviating the disadvantages of the prior art. The valve is in particular to be constructed in such a way that the tendency to deposit difficultly removable contaminants is reduced or substantially suppressed.
To solve this problem the invention proposes a valve having the features of claim
1
.
In the case of valves according to the preamble, the technical problem is inventively solved in that at least one sealing groove is connected through the associated valve body in fluid-conducting manner to the environment of the valve. In the case of double-seat valves the connection can particularly lead to the leakage cavity. Preferably such a connection is provided in all sealing grooves used for sealing against the valve seat. Thus, in addition to the groove opening facing the associated valve seat through which an inserted sealing body can project, a sealing groove has a connection leading out of the interior of the sealing groove to the environment. As a result, on inserting a sealing body, it is not possible for air inclusions to form, which can offer potential spaces for deposits. Thus, the air in the sealing groove displaced by the sealing material on fitting does not have to escape through the valve seat-facing groove opening reduced in size or closed normally by the sealing body to be inserted, but can instead be displaced by the inserted seal directly through the valve body and into the open. The at least one fluid pipe or line through the valve body also offers the possibility of cleaning the vicinity of the sealing groove and inserted sealing means by appropriate rinsing from the rear, i.e. through the at least one fluid line in the direction of the valve seat-facing groove opening. The rear opening of a sealing groove also permits a rapid leak indication if a seal tears. Whereas up to now in the case of a seal tear leaking fluid had to pass along the valve seat to the seal in order to be detactable, there is now an optionally shorter leakage flow path transversely to the circumferential direction of the seal through the sealing groove, which can aid in a much earlier leak indication, so that possibly greater contamination can be prevented by the replacement of seals in good time. The fluid-conducting connection between the sealing groove and the environment through the valve body can preferably be implemented by several, e.g. four fluid channels or bores with a radial fraction preferably regularly distributed round the sealing groove circumference. These fluid channels can e.g. issue into a hollow inner space of a valve body open to the environment and/or in the case of double-seat valves into the leakage cavity.
According to a further development, another measure for preventing the formation of deposits results from the fact that at least one and preferably all the sealing grooves have a through, convexly curved, particularly circular cross-section. In the latter can be inserted a cross-sectionally adapted, particularly cross-sectionally circular seal, normally in a slightly compressed state. As opposed to the known profiled, particularly dovetailed sealing grooves more particularly used with double-seat valves, an angle-free inner contour of the sealing groove offers no contaminant collecting points, because there is no possibility of a migration behind the sealing body and a deposition of contaminants of pockets in the vicinity of inner edges not filled by sealing material. A substantially circular sealing body cross-section also permits the smallest possible elastomer surface, which is also advantageous from the hygienic and cleaning standpoints.
A further development of a double-seat valve is characterized in that the seals of both the first valve body and the second valve body are constructed as radial seals. The latter preferably cooperate with a substantially cylindrical valve seat or face, which is formed between the housing spaces, particularly by the actual valve housing, but can also be provided on an insert separate from the valve housing. Unlike in the case of conventional solutions, no axially acting pressing force is necessary for sealing purposes. Therefore the drive for the axial movement of the valve body need only be sufficiently powerful to counteract axial forces caused by fluid pressure in the housing spaces. The drive does not have to apply an axial force or pretension for the sealing function. If such valves are pneumatically operated, they can be switched or actuated with much lower air pressures down to e.g. max 4 to 5 bar. Conventional valves, in which the sealing function is brought about by axial pressing of a valve body onto the associated valve seat, generally require between approximately 6 and approximately 8 bar. Therefore a drive according to this preferred development can be designed in a less expensive, lighter and smaller manner.
Whereas known double-seat valves

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