JPH0658459A - Double sealing type high-purity fluid valve - Google Patents

Abstract

PURPOSE: To provide a bellows type shield valve which is of a double sealing type and capable of preventing contamination of high purity fluid. CONSTITUTION: This valve includes a valve seat 18 to block a flow through a pipe 14 and a sealing member 16 to be engaged in a closed state. A control rod 24 moves the sealing member. A first bellows 22 is connected between an end of a valve stem housing 20 and the sealing member 16. A pipe 14 and the valve are surrounded in an outside shell 30. A second bellows 34 is set on the inside of the first bellows 22. A space 36 between the bellows is communicated to a space 38 between the valve and the outside shell 30. Fluid must pass separate double walls made of metal before leaking to the atmospheric air. That is, fluid is doubly sealed in the valve of bellows structure and necessity of using an O ring or a packing gland is eliminated by using the bellows, and accordingly, it is possible to prevent contamination of fluid by them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of high-purity and dangerous fluid shield valves, and in particular to the ability to detect leaks before they leak to the environment. The present invention relates to a high-purity fluid shield valve capable of double-sealing fluid so as to prevent clogging and such leakage and prevent contamination of the high-purity fluid. The valves of the present invention are typically used to control the flow of highly flammable or toxic fluids or fluids that are very harmful to the environment.

[0002]

BACKGROUND OF THE INVENTION The present invention is a sophisticated instrument used in applications where the fluid flowing through the valve must be maintained at a very high level of purity and therefore must not be contaminated by the materials used in the valve. It is an improvement of the model valve. Therefore, the valve does not use packing material or O-ring seals. Instead, a sealing member, which moves into and out of sealing engagement with the valve seat, is attached to one end of the bellows to allow its movement. In this manner, all of the surfaces that are wetted or contacted by the fluid (except the sealing member itself) are typically type 316L.
To 321 stainless steel. Such valves are very reliable and effective in preventing fluid contamination when used within their rated values. Such valves are often used in the semiconductor industry where extremely high purity gases are important.

FIG. 1 illustrates, in simplified form, a bellows shield valve 12 for high purity fluid of the type known in the art and manufactured by the Applicant. Valve 12
It is shown installed on the pipe 14. As shown in FIG. 1, the valve 12 includes a sealing member 16 that sealingly engages a valve seat 18 to block flow through the pipe 14. The sealing member 16 moves the control rod 2 in the direction of the arrow 26.
By moving 4 the valve seat 18 is pressed into a sealing engagement. The movement of the control rod 24 can be brought about by the rotation of a manual wheel or by actuation of a pneumatic drive.

In order to allow the movement of the sealing member 16 while maintaining the closed system, the bellows 22 is provided in the valve shaft housing 2.
It is connected between the zero end 28 and the sealing member 16. With the exception of the sealing member 16, all of the surfaces that are wetted or contacted by the fluid are metal surfaces and O-to comply with the requirement of not introducing contamination into the fluid.
It is important that no ring or sealing gland is used.

By the way, despite the high reliability and quality of the shield valve capable of preventing the contamination of these high-purity fluids,
In addition, there are situations in which leakage of fluid into the surrounding environment cannot be tolerated. For example, leaks of gaseous hydrogen pose a risk of explosion which, if accumulated, would destroy the entire factory. A technique called double containment has been developed in industry for these extremely dangerous applications. The technical concept is to enclose all parts of the system where hazardous fluids are used with an outer shell that contains the leaking fluid. For this,
Coaxial tubes, elbows and other parts were developed.

The Catalog of Curtain Systems Incorporated, located in Middlebury, Connecticut, USA, is catalog No. 250-035-316L-500.
At, a double containment diaphragm valve is shown.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to develop a bellows type shield valve which is of a double containment type and which can prevent contamination of a high purity fluid. The diaphragm valve is of a different type than the valve that uses a bellows. It is not clear if the double containment technique can be used with valves using bellows and the presence of double containment diaphragm valves is of little reference as the travel path length in bellows valves is several times greater than that in diaphragm valves. . Therefore, there is no prior art that serves as a reference for solving the problem of developing a double containment type bellows valve for high purity fluid.

[0008]

SUMMARY OF THE INVENTION In accordance with the present invention, this object is to provide an outer shell of a valve having a hole surrounding the body of the valve and having a hole aligned with the opening in the valve body through which the control rod extends. This is accomplished by providing a second bellows that extends coaxially inside the bellows and connects the outer shell to the sealing member. Thus, the outer shell and the second bellows completely surround the valve body and the first bellows.

Thus, the present invention also includes a body defining an internal passageway and a valve seat surrounding the internal passageway, and in a sealing engagement with the valve seat to prevent fluid flow through the internal passageway. A sealing member movable away from the sealing engagement to permit fluid flow through the internal passageway, a body opening, and extending into the body around the opening to provide movement of the sealing member, and A shield valve of the type that does not use O-rings or packing lands, including a first bellows connecting the sealing member to the body, the outer side having a hole surrounding the shield valve body and aligned with the body opening. A shell and a second bellow extending inside the first bellows around the outer shell hole and connecting the outer shell to the sealing member, the outer shell and the second bellows being the valve body. Providing a shielding valve, characterized in that completely surrounds the first bellows.

It is important to note that the type of seal provided by the present invention includes a metallic double wall between the fluid and ambient air except for the sealing member itself. That is,
Hazardous fluids must penetrate metallic double walls before they reach the surrounding atmosphere.

The present dual containment system allows for the detection of leaks inside the valve and the repair of any dangerous fluid before it reaches the ambient atmosphere. In the first embodiment using a valve, the space between the metal double walls is maintained under reduced pressure by a vacuum pump and even the presence of tiny holes in the valve allows traces of hazardous fluid to enter the evacuated space between the metal walls. Aspirate, where dangerous fluids can be detected and aspirated by a vacuum pump.

In a second mode of use of the present invention, the space between the double metal walls is maintained at a higher pressure than the dangerous fluid, so that if a small hole develops in the valve, pressurized gas will leak the dangerous fluid. The pressurized gas, which is of high purity and which may be inert, instead penetrates into the inner chamber where the dangerous fluid is present and is detected there.

It will thus be appreciated that the dual containment structure allows for the detection of leaks well before even a small amount of hazardous fluid reaches the ambient atmosphere.

[0014]

An outer shell having a hole surrounding the shield valve body and aligned with the valve body opening, and a second shell extending within the first bellows around the outer shell hole and connecting the outer shell to the sealing member. The valve body and the first by the bellows
Completely encircles Bellows and. Hazardous fluids must pass through separate double-walled metal walls before they leak to the atmosphere. That is, the fluid is doubly contained in the bellows type valve. Moreover, the need to use O-rings or packing lands is eliminated, thus preventing contamination of the fluid by them.

[0015]

FIG. 2 is an explanatory view showing the principle of the present invention. To provide double containment, pipe 14 and valve 12
It should be clear that must be enclosed within the outer shell 30. The outer shell 30 is spaced from the surrounding part.

The space inside bellows 22 also needs to be enclosed because of the potential for leakage through bellows 22. If the use of O-rings is allowed, then it is straightforward to place the O-ring around the control rod 24 around the opening 32. However, the use of O-rings is not allowed, so another new strategy must be found.

As a result of many studies, the present inventor has conceived to install the second bellows 34 inside the first bellows 22. To the knowledge of the inventor, this method has never been used for valves. The space 36 between the bellows communicates with the space 38 between the valve and the outer shell 30.

Although this scheme was a viable solution, the structure itself shown in FIG. 2 is in principle
Since its assembly structure is difficult or impossible in practice, there are many problems to be solved and it is not yet practical. As a result of trials, it was found that the problem can be solved by the structure shown in FIG. 3 and the present invention can be put into practical use.

FIG. 3 shows the manner in which the valve stem housing 20 and outer shell are closed in the preferred embodiment. The valve stem closure 40 allows for assembly. The process of assembling the parts will be described.

First, the second bellows 34 are welded to the sealing member base 42 of FIG. 2, and the rear first bellows 22 are also welded to the sealing member base 42. The control rod 24 is then inserted through the hole 44 in the closure 40 and the rear second bellows 34 is welded to the closure 40 as shown in FIG. The first bellows 22 are then also welded to the closure 40.

The subassembly consisting of the sealing member, both bellows and the closure is then inserted into the already mounted valve stem housing 20 and welded at weld 46 along the perimeter. The assembly is completed by slip-fitting the cylindrical portion of outer shell 30 around closure 40 and welding it accordingly with welds 50 and 52.

In the present invention, the space between the two bellows and the space 38 between the valve shaft housing 20 and the outer shell 30.
Means useful for communicating with each other are incorporated. An annular recess 56 is provided in the closure 40 and the space 36 between the two bellows is connected by a single or multiple perforations. Perforations 54 are shown as a representative example.

In summary, the space 58 is wetted or contacted by the dangerous fluid. The spaces 36 and 38 may be maintained at a higher pressure or a lower pressure than the space 58 as described above. The space 60 is open to the atmosphere through the hole 44. In the first embodiment using a valve, the space between the metal double walls is maintained under reduced pressure by a vacuum pump and even the presence of tiny holes in the valve allows traces of hazardous fluid to enter the evacuated space between the metal walls. Aspirate, where dangerous fluids can be detected and aspirated by a vacuum pump. In a second embodiment using a valve, the space between the double metal walls is maintained at a higher pressure than the dangerous fluid, and if small holes develop in the valve, the pressurized gas prevents the dangerous fluid from leaking, Pressurized gas, which may be highly pure and inert, enters the interior of the inner chamber where dangerous fluids are present and is detected there.

As a result of this construction, the hazardous fluid in space 58 must pass through separate double-walled metal walls before it can escape to the atmosphere. That is, the fluid is doubly contained in the bellows type valve, and the need to use O-rings or packing lands is eliminated, thereby preventing contamination of the fluid by them.

[0025]

The present invention provides a structure that is simple to assemble as a bellows valve for dual containment high purity fluids that is particularly adapted for managing the flow of hazardous fluids such as highly flammable or toxic fluids.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view of a bellows type high purity fluid valve known in the prior art.

FIG. 2 is a partial cross-sectional view showing the principle of a double containment type bellows type shield valve for a high purity fluid according to the present invention.

FIG. 3 is a partial cross-sectional view showing a valve stem closing portion according to a preferred embodiment of the present invention.

[Explanation of symbols]

 12 Bellow type shield valve 14 Pipe 16 Sealing member 18 Valve seat 20 Valve shaft housing 22 Bellow 24 Control rod 30 Outer shell 32 Opening 34 Second bellow 36 Space between bellows 38 Space between valve and outer shell 40 Closing body 42 Sealing member base 44 Hole 46, 50, 52 Welded portion 54 Perforated 56 Annular recess 58, 60 Space

 ─────────────────────────────────────────────────── —————————————————————————————————————————————————————————————————————— inventors That up out up out up out Mill Mill Street 1553 San Luis Obispo, California

Claims (1)

[Claims] 1. A body comprising an internal passageway and a valve seat surrounding the internal passageway, and in sealing engagement with the valve seat to prevent flow of fluid through the internal passageway and of fluid through the internal passageway. A sealing member movable away from the sealing engagement to permit flow, a body opening, and extending into the body around the opening to provide movement of the sealing member and the sealing member to the body. A shield valve of the type that does not use O-rings or packing lands, the outer shell having a hole surrounding the shield valve body and aligned with the body opening; A second member extending within the first bellows around a shell hole and connecting the outer shell to the sealing member.
And a second bellows completely surrounding the valve body and the first bellows.