GB2025577A

GB2025577A - Valve arrangements

Info

Publication number: GB2025577A
Application number: GB7918620A
Authority: GB
Original assignee: AGA AB
Current assignee: Linde Sverige AB
Priority date: 1978-05-31
Filing date: 1979-05-29
Publication date: 1980-01-23
Also published as: BR7903390A; IT1120916B; DE2920882A1; DE2920882C2; FR2427531A1; DK222379A; SE411793B; ES481022A1; AR216217A1; JPS5524283A; FI791705A7; SE7806293L; NO791795L; GB2025577B; NL7904303A; IT7923069A0

Abstract

A valve arrangement for controlling the residual pressure of a pressure- medium system e.g. a gas container. The residual-pressure valve includes a body 12 sealingly displaceable in a flow passage 11 and is biased against a first stop 32, e.g. by spring 19. A valve member 15 having a spindle 16 is displaceable in body 12 to open and close a seal 20 which engages a seat 14 in the closed position. Member 15 is biased to closed position by a spring 18. Strength of spring 18 sets residual pressure. A second stop 33 is provided to permit forcible opening of valve by displacement of said valve body 15 to the right whereby stop 33 arrests spindle 16 and thereby opens valve for e.g. filling of an associated gas container. <IMAGE>

Description

SPECIFICATION Valve arrangements The present invention relates to valve arrangements.

In certain pressure-medium systems for gaseous or liquid media, it is desirable to prevent the systems from being emptied completely. If, for example, a gas system intended for uncontaminated so-called noble gases is completely emptied, air may enter the system, whereby when the system is later filled with noble gas the gas will become contaminated. To prevent this there is usually arranged at a suitable location, e.g. the location of the outlet of the system, a a valve which is set to the lowest pressure to which the system can be emptied, i.e. the residual-gas pressure. The valve can also be designed to permit gas to be charged to the system. Subsequent to filling the system, the valve is closed and then serves solely to ensure that the system will not be emptied beneath said level.Although a number of such valve constructions have been provided, all have certain disadvantages. Moreover, there construction is often complicated.

A particular problem encountered with containers for noble gases is that containers returned by consumers are almost always practically empty of gas and the valve of the container has not been fully closed. As a result, atmospheric air is able to enter the gas container for instance as a result of changes in temperature, thereby contaminating any noble gas subsequently charged to the system. Conse quently, a container returned in the aforementioned condition must be purified, which is costly. Normal ly, this purifying procedure requires the flask or container to be cacuum-pumped or flushed with the gas with which the system is to be filled. In addition, it is often necessary to first heat the flask, in order to remove any moisture which has collected on, inter alia, the flask walls.

One method of avoiding these difficulties is to provide the valve of the gas container with a special valve, a so-called residual-pressure valve, which prevents the container from being emptied of its contents to an extent such that the pressure in the flask is beneath atmospheric or ambient pressure.

Thus, the valve is constructed in a manner such as to ensure that the gas pressure in the container is of such a high level that ambient air is unable to pass into the container. The residual gas pressure in the container should lie within the range of 0.1 to 0.2 Megapascals (e).

Certain types of known residual-gas valves have, inter alia, the disadvantage that the sealing pressure against total emptying of the gas content of the flask has been unsatisfactory. Because of this, it has been necessary to increase the level to which the flask can be emptied to one which is found unacceptable by the consumer, since he thereby loses too high a percentage of the contents of the flask. Other kinds of residual-gas valves require re-setting manually when filling the container, which complicates the filling operation and places particular requirements on the personnel responsible. Valve arrangements are also known in which the residual-gas valve is automatically re-set when a filling operation is commenced. Such valves, however, have a construction which comprises a multiplicity of elements, which is difficult and expensive to manufacture.

Furthermore, this lattertype of valve requires a lot of space in its longitudinal direction, which is an obvious disadvantage.

According to one aspect of the invention, there is provided a valve arrangement for use between a first region whose pressure is to be maintained above a predetermined level and a second region of normally lower pressure, said arrangement comprising a flow passage; a valve body sealingly displaceable in the flow passage; a first stop means against which the valve body is biased in use by pressure of said first region; a valve member mounted in said body for movement relative thereto to open and close said passage and biased into the closed position by a force setting said predetermined level; and a second stop means against which the valve member is arranged to abut following displacement of said valve body away from said first stop means whereby said passage can be opened.

Preferably, said valve body is biased towards said first stop means by resilient means.

Preferably, there are provided two springs arranged coaxially about said valve member one of said springs providing said force and the other of said springs biasing said valve member towards the first stop means.

Expediently, there is provided means for receiving a mechanical element in said passage to displace said valve body away from said first stop means for bringing said valve member into abutment with said second stop means.

It is possible to produce displacement of said valve body away from said first stop means in responce to increased pressure of pressure medium in said second region.

According to a further aspect of the invention, there is provided a pressure medium system having; a first region whose pressure is to be maintained above a predetermined level; a second region of normally lower pressure; and a valve arrangement according to said one aspect of the invention connected between said first and second regions.

For a better understanding of the invention, and to show how the same may be carried into effect, reference will now be made, by way of example to the accompanying drawing, in which: Figure 1 is a longitudinal sectional view of gas-container valve provided with a residualpressure valve: Figure 2 illustrates the residual pressure valve partly in section, in a position closed against filling; and Figure 3 illustrates partly in section, the residualpressure valve in a poition open forfilling.

The valve assembly illustrated in Figure 1 comprises a valve housing 1 which can be screwed onto a gas container or flask with screw thread 6. Arranged in the valve housing is a longitudinally extending gas passage 7 for communication with the gas container. Communicating with the passage 7 is a further passage 11, which extends transversely of said passage 7 and which is intended to be connected e.g. to a gas-consumer. The passage 7 can be closed by means of a valve plunger 2 having a plug 2a by moving plug 2a into abutment with a seating 8 in housing 1. Plunger 2 is operated by rotating a knob 4 connected to the valve plunger. The plunger 2 is mounted in a guide sleeve and sealed thereagainst via a seal 3. When knob 4 is rotated to open the valve, plunger 2 and plug 2a are lifted by means of a valve spring 5, thereby to provide communcation between the passages 7 and 11.

A gas-regulator unit, or a hose-coupling or pipecoupling, for example, is connected to a connection stub 9 of the assembly by means of screw threads 10, said passage 11 being arranged in said conriection stub 9. Arranged in the passage 11 is a residual-pressure valve which is illustrated in more detail in Figures 2 and 3 and operates to prevent pressure in the gas container dropping below a predetermined level.

The residual-pressure valve comprises an axially movable valve body 12, one half of which is sectioned in the figures. Body 12 is sealingly mounted for sliding movement in passage 11 and is sealed against the internal wall thereof by means of a sealing ring 22. The body 12 has the form of a sleeve and is provided with a bore 27. Arranged between an abutment surface in the bore 27 and the wall 28 of the main housing is a spring 19 biasing body 12 against a stop plate 21. The wall 28 is provided with through-holes 25 for the passage of gas. Holes 13 for the passage of gas are also provided in the sleeve-like body 12. Body 12 is provided with a valve seating 14 against which a valve member 15 provided with a seal 20 abuts.

Member 15 includes a spindle 16 which is arranged for axial movement centrally in body 12. The spindle is provided on the end thereof remote from seai 20 with a retaining element 17. Arranged between the element 17 and the bottom of bore 27 is a further spring 18. The springs 18 and 19 extend coaxially with the spindle 16. Arranged in a recess 26 in the stub 9 is the stop plate 21 for restricting movement of body 12 in the opening direction of the valve. A hole for enabling member 15 to move axially is arranged in plate 21, which is axially movable in recess 26, the movement being limited by a stop surface 32 in one direction.

As will be seen from Figure 2, the screw threads 10 on the stub 9 carry a threaded sleeve 23, which biases an element 29 into sealing engagement via a sealing ring 24 with stub 9. In this respect, the element 29 may be a device for connecting the valve assembly to a regulator or to a hose connection.

Figure 2 illustrates the conditions in which gas is delivered from the gas container. When the main valve is opened by rotation of knob 4, gas flows through the holes 25 into the bore 27 and through the holes 13. The gas pressure will lift valve member 15 against spring 18 and the seal 20 from the seating 14to allow the gas to flow out through the stub 9.

When the pressure of the gas in the flask has fallen to a value at which the force exerted by the spring 18 cannot be overcome, said pressure representing the desired residual-gas pressure, the valve member 15 returns to its seating and hence there is no risk of air leaking into the gas container.

When the gas container is to be filled, gas must pass through the residual-pressure valve means in the opposite direction, the valve closing direction.

Since the residual-pressure valve only comprises one seating 14and one valve member 15 itmeans that seating member 14 and member 15 must be separated from one another during a flask-filling operation. This is achieved by displacing the body 12 together with valve member 15 in the closing direction towards the wall 28 of the main housing.

When the spring retaining element 17 reaches the wall 28, the spindle 16 is unable to continue its axial movement, as illustrated in Figure 3. The body 12 however, can continue to move axially, causing the seating 14 to leave the seal 20 and member 15. The gas can then pass through the hole 13, the bore 27, the holes 25 and into the gas container via the main valve. To move the body 12 axially in the described manner, the element 29, which is screwed on the stub 9, as shown in Figure 2, is replaced by an element 29a having an extension 31 which bears on the axial plate 21 and displaces the sleeve-like body 12 in an axial direction towards the main valve, as shown in Figure 3. The plate 21 is displaced in the recess 26. The connecting element 29a seals against the stub 9via its sealing ring 24a.In orderto displace the valve body 12 towards the main valve it is necessary to overcome the force exerted by the spring 19. When the flask is filled with the desired amount of gas, the connecting element 29a is removed. The spring 19 will then return the residualpressure valve body 12 to its starting position. The prime purpose of the spring 19 is positively to ensure that the frictional force between the seal 22 and the wall of the stub 9 is overcome to close the valve. It is possible, however, to exclude the spring 19 when a sufficiently high gas pressure prevails in the gas container. Subsequent to filling the container, the pressure prevailing therein moves the valve body to the "emptying position" of the residualpressure valve means.Instead of the mechanical effect of the extension 31 on the residual-pressure valve body 12, it is also possible to permit the pressure of the gas during a filling operation, when said pressure is sufficiently high, to act directly on the valve body 12 and to move said body in said axial direction to the "filling position" of said valve body 12.

The mechanical forced opening ofthe residualpressure valve by means of the connecting element 29a is of course necessary when the gas flask is to be vacuum-pumped prior to being filled. Further, in this connection, it is also necessary to provide the return spring 19.

Thus there has been described a valve construction which comprises one single valve seat and one single valve member, which are common to the filling and emptying function of the valve. When filling the gas container with a pressure medium, the valve arrangement can be actuated either mechanically or by means of pressure exerted by the pressure medium. Return of the residual-pressure valve means to its original position subsequent to a filling operation can either be effected by the pressure of the pressure medium in the container, or by using a spring force. The spring 19 which effects said return of said valve means is arranged coaxially relative to the valve spindle and covers the residual-pressure spring 18, and hence the residual-pressure valve means requires but small space in its longitudinal direction. The described residual-pressure means thus comprises few elements, which are simple to assemble and which function fully satisfactorily.

The scope of the invention is not restricted to the described and illustrated embodiment, but can be modified within the scope of the following claims.

For example, the functions of the valve can be reversed, which means that the residual-pressure valve means can be mounted in a reversed position in the flow passage.

Claims

1. A valve arrangement for use between a first region whose pressure is to be maintained above a predetermined level and a second region of normally lower pressure, said arrangement comprising a flow passage; a valve body sealingly displaceable in the flow passage; a first stop means against which the valve body is biased in use by pressure of said first region; a valve member mounted in said body for movement relative thereto to open and close said passage and biased into the closed position by a force setting said predetermined level; and a second stop means against which the valve member is arranged to abut following displacement of said valve body away from said first stop means whereby said passage can be opened.

2. An arrangement according to claim 1 wherein said valve body is biased towards said first stop means by resilient means.

3. An arrangement according to claim 2 wherein there are provided two springs arranged coaxially about said valve member one of said springs providing said force and the other of said springs biasing said valve member towards the first stop means.

4. An arrangement according to claim 1,2 or 3 wherein there is provided means for receiving a mechanical element in said passage to displace said valve body away from said first stop means for bringing said valve member into abutment with said second stop means.

5. An arrangement according to claim 1,2 or 3 wherein means are provided to produce displacement of said valve body away from said first stop means in response to increased pressure of pressure medium in said second region.

6. A valve arrangement substantially as hereinb- efore described with reference to Figures 2 and 3 of the accompanying drawing.

7. A pressure medium system having; a first region whose pressure is to be maintained above a predetermined level; a second region of normally lower pressure; and a valve arrangement according to any one of claims 1 to 6 connected between said first and second regions.

8. A pressure medium system substantiaily as hereinbefore described with reference to Figure 1 of the accompanying drawing.

9. A valve arrangement arranged to prevent a pressure-medium system from being emptied to a level at which the pressure in said system is below a given set residual pressure, and for enabling said system to be filled or vacuum-pumped, said arrangement comprising a residual-pressure valve means arranged in a flow passage of said system, said valve means being set to said residual pressure and comprising a spring-biased valve body sealing against a seating, said spring bias corresponding to the set residual pressure, wherein the whole of the residual-pressure valve means is arranged sealingly displaceable in the flow passage; wherein there is arranged in said flow passage a first stop means against which the valve seating of the residualpressure valve means is arranged to abut when said valve means is displaced by means of the residual pressure in the system or by means of said residual pressure in combination with a spring means arranged between the valve seating and the wall of said passage, said residual-pressure valve means being openable by means of a pressure in the system exceeding said residual pressure; and wherein arranged in the flow passage on the opposite side of the residual-pressure valve means is a second stop against which the valve body of said valve means is arranged to abut subsequent to displacement of said valve means, by means of an external device or an externai pressure medium, said residual-pressure valve means being forcibly opened.