GB2201489A - Valve arrangement - Google Patents

Abstract

A valve arrangement for supplying gas from a high pressure supply has a pressure reducing arrangement and a suction demand arrangement carried by a single housing 20. The housing is a substantially cylindrical hollow body 24 with an internal partition 22 to define two opposed cavities 36, 52. The pressure reducing arrangement is associated with one cavity and the suction demand arrangement with the other cavity. Each cavity is closed off by a diaphragm 28, 50, which serves to control an associated valve closure member 42, 56 of the presstire reducing and suction demand arrangements respectively. <IMAGE>

Description

VALVE ARRANGEMENTS THIS INVENTION relates to a valve arrangement for supplying gas from a high pressure supply thereof.

According to the invention there is provided a valve arrangement for supplying gas from a supply thereof that is at a high pressure, which includes a housing; and a pressure reducing arrangment for providing gas at a substantially lower pressure than that of the supply and a suction demand arrangement for delivering low pressure gas in response to an applied suction, both arrangements being carried by the housing.

The housing may comprise a substantially cylindrical hollow body with an internal partition to define two opposed cavities and the pressure reducing arrangement is associated with one cavity and the suction demand arrangement is associated with the other cavity.

Each cavity máy be closed off by a diaphragm and the valve arrangement may include an inlet connectable to a high pressure supply, and an outlet.

The pressure reducing arrangement may include a first diaphragm which partly defines a first chamber the rest of the chamber being defined by the housing; a first urging means for urging the first diaphragm inwardly to decrease the size of the first chamber; a first communication opening between the inlet and the first chamber; a first closure member located outside the first chamber and engageable with a first valve seat defined about the first communication opening on the upstream side thereof; and a first displacing means connected between the first diaphragm and the first closure member for displacing the first closure member away from the first valve seat upon inward displacement of the first diaphragm. An auxiliary urging means may also be provided to urge the first closure member towards the first seat.

The first urging means may be externally adjustable to vary the force exerted by it on the first diaphragm.

The suction demand arrangement may be similar in construction to the pressure reducing arrangement, except that it does not have an urging means. Thus, it may include a second diaphragm which partly defines a second chamber and is inwardly displaceable by a negative pressure within the second chamber; a second closure member located outside the second chamber and engageable with a second valve seat defining a second communication opening between the first chamber and the second chamber; and a second displacing means connected between the second diaphragm and the second closure member for displacing the second closure member away from the second valve seat upon inward displacement of the second diaphragm when the pressure in the second chamber is decreased below ambient pressure. The second displacing means may include a lever with a mechanical advantage that is greater than unity.A further auxiliary urging means may be provided to urge the second closure member towards the second seat.

The valve may further have an excess flow shut-off valve at its inlet and may also have a pressure indicating means for indicating the pressure at the inlet.

The invention is described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 shows a plan view of a valve in accordance with the invention; Figure 2 shows a sectioned view along line II-II in Figure 1; and Figure 3 shows a sectioned view along line III-III in Figure 1.

Referring to the drawings, a valve for supplying gas from a high pressure supply thereof (not shown) is designated generally by reference numeral 10. The valve 10 comprises a housing 12 which has an inlet port 14, an outlet port 16 and a pressure indicating arrangement 18.

The housing 12 comprises a substantially circular cylindrical body 20 which has a central web 22 with a cylindrical wall 24 extending on one side and a similar cylindrical wall 26 extending on the other side thereof. The recess defined by the cylindrical wall 26 is closed off by a first diaphragm 28 that is urged inwardly by means of a compression spring 30. One end of the spring 30 bears against the first diaphragm 28 and the other end bears against a washer 32 which may be displaced in and out by a screw-threaded plunger 34. The central web 22, the cylindrical wall 26 and the first diaphragm 28 define a first chamber 36.

The first chamber 36 communicates with the inlet port 14 by means of a passage 38 in the web 22 and a communication opening 40. A first closure member 42 is located outside the first chamber 36 and is urged into sealing engagement with a valve seat that is outside the first chamber 36 and which defines the first communication opening 40. The first closure member 42 is urged into sealing engagement with the valve seat by means of a first auxiliary spring 44. A filter cap 46 is provided between the passage 38 and the valve seat. A pin 48 is located between the first diaphragm 28 and the first closure member 42, such that inward displacement of the first diaphragm 28 is transferred to the first closure member 42, displacing it away from its valve seat such that gas may flow from the inlet port 14 into the first chamber 36.As the pressure builds up in the first chamber 36 the first diaphragm 28 will be displaced outwardly and when the pressure within the first chamber 36 reaches a predetermined value determined by the force exerted by the spring 30, the first closure member 42 will be allowed to engage its seat and thereby close the first communication opening 40. If gas is allowed to escape from the first chamber 36 then the pressure therein will decrease causing the first diaphragm 28 to move inwardly to once again displace the first closure member 42 and open the first communication opening 40. The pressure in the first chamber 36 then builds up and the first communication opening 40 is again closed.It will be appreciated that, in operation, the pressure in the first chamber 36 is less than that supplied to the valve 10 at its inlet port 14, the supply pressure accordingly being reduced to a predetermined value which is determined by the position of the plunger..34 which varies the pressure of the spring 30.

The recess formed by the cylindrical wall 24 is closed by a second diaphragm 50 to define a second chamber 52. The second chamber 52 communicates with the first chamber 36 via a second communication opening 54 that is defined in the central web 22. A second closure member 56 located on the side of the second communication opening 54 faces towards the first chamber 36 to sealingly engage a second valve seat defined about the second communication opening 54. The second closure member 56 is urged into seating engagement with its valve seat by means of a further auxiliary spring 58. A further filter cap 60 is provided.

The second closure member 56 is displaced away from its seat to open the second communication opening 54 by means of a further pin 61 and a lever arrangement formed by a disc portion 68 which is attached at an edge region to one end of a cranked arm 62. The other end 66 of the arm 62 is located between two spaced projections 64 fast with the diaphragm 28. The disc portion 68 engages the pin 61 and is located by a lip formation 70 that engages an edge region of the disc 68 that is opposite to the arm 62. The end 66 of the arm 62 is not pivotally attached to the projections 64 and is merely located thereby such that it may move relative thereto. It will be appreciated that in use the lip formation 70 acts as a fulcrum for the lever arrangement formed by the disc 68 and the arm 62. The second chamber 52 is in direct communication with the outlet port 16.

It will be appreciated that the second communication opening 54 is normally closed. However, if the pressure in the second chamber 52 is decreased below ambient pressure the second diaphragm 50 is inwardly displaced causing the lever arrangement formed by the arm 62 and disc 68 to pivot about the lip formation 70 and push the second pin 61 inwardly to displace the second closure member 56 away from its seat. Gas will then flow from the first chamber 36 into the second chamber 52, increasing the pressure in the second chamber 52 causing the second diaphragm 50 to be displaced outwardly, thereby allowing the second closure member 56 to engage its seat.

The inlet port 14 is at the free end of a stem 71; An excess flow shut-off arrangement 72 is provided within the stem 71 close to the inlet port 14. This arrangement 72 has a ball 74 which is urged away from a downstream seat 76 by a spring 78. If the stem 71 is broken to provide a relatively free flowpath for gas.to flow, an excess flow rate will result which will cause the ball 74 to be displaced against the seat 76, closing it off and thereby shutting off the flow. The pressure of the gas will then keep the ball 74 seated against its seat 76.

The central web 22 has a further passage 80 which communicates with the passage 38. A hollow member 82 is secured to the web 22 in communication with the passage 80. The member 82 has an internal bore in which is located a piston 84 that is urged towards the passage 80 by a spring 86. An indicating pin 88 is fast with the piston 84 and projects into a window 90. The extent to which the spring 86 is compressed will depend on the pressure of gas in the passage 80 and, accordingly, the extent to which the pin 88 projects into the window 90 is an indication of the pressure supplied to the valve 10.

Claims (13)

1. A valve arrangement for supplying gas from a supply thereof that is at a high pressure, which includes a housing; and a pressure reducing arrangment for providing gas at a substantially lower pressure than that of the supply and a suction demand arrangement for delivering low pressure gas in response to an applied suction, both arrangements being carried by the housing.

2. The valve arrangement of Claim 1, in which the housing comprises a substantially cylindrical hollow body with an internal partition to define two opposed cavities and the pressure reducing arrangement is associated with one cavity and the suction demand arrangement is associated with the other cavity.

3. The valve arrangement of Claim 2, in which each cavity is closed off by a diaphragm.

4. The valve arrangement of Claim 1, which includes an inlet connectable to the high pressure supply, and an outlet.

5. The valve arrangement of Claim 4, in which the pressure reducing arrangement includes a first diaphragm; a first chamber defined by the first diaphragm and a part of the housing; a first urging means for urging the first diaphragm inwardly to decrease the size of the first chamber; a first communication opening between the inlet and the first chamber; a first valve seat about the first opening on the upstream side thereof; a first closure member engageable with the first valve seat to close the first opening; and a first displacing means connected between the first diaphragm and the first closure member for displacing the first closure member away from the first valve seat upon inward displacement of the first diaphragm.

6. The valve arrangement of Claim 5, which includes an auxiliary urging means for urging the first closure member towards the first valve seat.

7. The valve arrangement of Claim 5, in which the first urging means is externally adjustable to vary the force exerted by it on the first diaphragm.

8. The valve arrangement of Claim 5, in which the suction demand arrangement includes a second diaphragm; a second chamber defined by the second diaphragm and part of the housing; a second communication opening between the first chamber and the second chamber; a second valve seat about the second opening on the first chamber side thereof; a second closure member engageable with the second valve seat to close the second opening; and a second displacing means connected between the second diaphragm and the second closure member for displacing the second closure member away from the second valve seat upon inward displacement of the second diaphragm.

9. The valve arrangement of Claim 8, which includes a further auxiliary urging means for urging the second closure member towards the second valve seat.

10. The valve- arrangement of Claim 8, in which the second displacing means includes a lever arm with a mechanical advantage that is greater than unity.

11. The valve arrangement of Claim 1, which includes an excess flow shut-off arrangement.

12. The valve arrangement of Claim 1, which includes a pressure indicating means for indicating the supply pressure.

13. A valve arrangement substantially as described in the specification with reference to the accompaying drawings.