GB2201490A - Suction demand valve - Google Patents

Abstract

A suction demand valve has a closure member 42 that closes a communication opening between an inlet and outlet. A diaphragm 28 is in fluid communication with the outlet and is interconnected with the closure member via a lever arm 69. The inlet and the closure member can withstand a pressure of at least 1000 kPa so that the valve can be connected directly to a high pressure cylinder. The diaphragm and the mechanical advantage of the lever arm are sufficiently large in comparison with the communication opening for the closure member to be displaced when a slight suction pressure is applied to the outlet. The lever arm has a head portion 68 and a tail portion 62. An edge part of the head portion engages a lip 70 adjacent the opening, which acts as a fulcrum, a further part of the head portion engaging the closure member via a pin 60. The tail portion is held, by two ears, in a floating manner, against the diaphragm. <IMAGE>

Description

VALVES THIS INVENTION relates generally to valves and more particularly to a high pressure suction demand valve and to a high pressure cylinder in combination with a suction demand valve.

According to the invention there is provided a high pressure suction demand valve which includes an inlet; a control chamber at least partly defined by a diaphragm and partly by a rigid wall with a communication opening being defined in the rigid wall whereby the inlet is in fluid communication with the chamber; a valve seat defined about the communication opening on the inlet side of the wall; a closure member engageable with the valve seat to open and close the opening; an urging means for urging the closure member into sealing engagement with the seat; a displacing means connected between the diaphragm and the closure member for displacing the closure member away from the seat upon inward displacement of the diaphragm; and an outlet in fluid communication with the chamber; with the inlet, the rigid wall, and the closure member being able to withstand a pressure of at least 1000 kPa.

It will be appreciated that with such a demand valve, it may be directly connected to the outlet port of a high pressure gas cylinder without the need for any pressure reducing arrangement or any other flow regulating arrangement. Thus the suction demand valve may include a connection means for connecting the inlet directly to an outlet port of a high pressure gas cylinder.

Further according to the invention there is provided a valve for controlling the flow of a fluid, which includes a diaphragm; a flow opening defining member which defines an opening through which the fluid may flow; a closure member for closing the opening, that is displaceable into and out of closing engagement with the flow opening defining member to close and open the opening; a displacing member which has a head portion and a tail portion extending therefrom; and a fulcrum defining formation fast with the flow opening defining member and adjacent the opening, the fulcrum defining formation engaging an edge part of the head portion, with a further part of the head portion engaging the closure member and with the tail portion engaging the diaphragm.

The valve according to.this aspect of the invention'may also be a suction demand valve, which may be used with low or high pressure supplies.

A pair of spaced lugs or ears may be provided on the diaphragm or on an auxiliary plate which assists in locating the tail portion of the displacing member.

Still further according to the invention there is provided a high pressure gas cylinder in combination with a high pressure suction demand valve in accordance with the invention.

The cylinder may, in particular, contain acetylene.

The demand valve may further include an excess flow shut-off valve arrangement at its inlet.

The invention is now described, by way of an example, with reference to the accompanying drawings, in which: Figure 1 shows a sectioned view of a high pressure suction demand valve connected to an acetylene cylinder; and Figure 2 shows a plan view of the valve itself, Figure 1 being a view along line I-I.

Referring to the drawings, a suction demand valve for supplying gas from a high pressure cylinder is designated gene rally by reference numeral 10 the cylinder being designated by reference numeral 11. 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 web 22 with a cylindrical wall 24 extending on one side thereof. The recess defined by the cylindrical wall 24 is closed off by a diaphragm 28. The web 22, the cylindrical wall 24 and the diaphragm 28 define a chamber 36. The- chamber 36 communicates with the inlet port 14 by means of a passage 38 in the web 22 and a communication opening 40. A closure member 42 is located outside the chamber 36 and is urged into sealing engagement with a valve seat that is outside the chamber 36 and which defines the communication opening 40. The closure member 42 is urged into sealing engagement with the valve seat by means of an auxiliary i art spring 44. A filter cap 46 is provided between the passage 38 and the valve seat.

The closure member 42 is displaced away from its seat to open the communication opening 40 by means of a pin 60 and a lever arrangement 69 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 60 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 chamber 36 is in direct communication with the outlet port 16.

It will be appreciated that the communication opening 40 is normally closed. However, if the pressure in the chamber 36 is decreased below ambient pressure the diaphragm 28 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 pin 60 inwardly to displace the closure member 42 away from its seat.

Gas will then flow from the inlet port 14 into the chamber 36, increasing the pressure in the chamber 36 causing the diaphragm 28 to be displaced outwardly, thereby allowing the closure member 42 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 inlet port 14, passage 38, the valve seat around the communication opening 40 and the closure member 42 can withstand a pressure of at least 1000 kPa. The lever arrangement 69 has a sufficiently large mechanical advantage in relation to the effective area of the communication opening 40 and the diaphragm 28 to displace the closure member 42 if the pressure in the chamber 36 drops slightly in comparison with ambient pressure.

Claims (16)

1. A high pressure suction demand valve which includes an inlet; a control chamber at least partly defined by a diaphragm and partly by a rigid wall with a communication opening being defined in the rigid wall whereby the inlet is in fluid communication with the chamber; a valve seat defined about the communication opening on the inlet side of the wall; a closure member engageable with the valve seat to open and close the opening; an urging means for urging the closure member into sealing engagement with the seat; a displacing means connected between the diaphragm and the closure member for displacing the closure member away from the seat upon inward displacement of the diaphragm; and an outlet in fluid communication with the chamber: with the inlet, the rigid wall, and the closure member being able to withstand a pressure of at least 1000 kPa.

2. The valve claimed in Claim 1, which includes a connection means for connecting the inlet directly to an outlet port of a high pressure gas cylinder.

3. The valve claimed in Claim 1, which includes an excess flow shut-off arrangement at the inlet.

4. The valve claimed in Claim 1, in which the displacing means includes a lever arm.

The valve claimed in Claim 4 in which the mechanical advantage of the lever arm. and the surface area of the diaphragm are sufficiently large in comparison with the area of the communication opening for the closure member to be displaced in use, with a small pressure differential across the diaphragm and a supply pressure of at least 1000 kPa.

6. The valve claimed in Claim 5, which includes a pin and in which the lever arm has a head portion and a tail portion extending from the head portion, with a free end of the tail portion being engaged by the diaphragm and a part of the head portion engaging the closure member by means of the pin.

7. The valve claimed in Claim 6, which includes a fulcrum defining formation which is engaged, in use, by an edge part of the head portion.

8. The valve claimed in Claim 1, which includes a filter means between the inlet and the communication opening.

9. A valve for controlling the flow of a fluid, which includes a diaphragm; a flow opening defining member which defines an opening through which the fluid may flow; a closure member for closing the opening, that is displaceable into and out of closing engagement with the flow opening defining member to close and open the opening; a displacing member which has a head portion and a tail portion extending therefrom; and a fulcrum defining formation fast with the flow opening defining member and adjacent the opening, the fulcrum defining formation engaging an edge part of the head portion, with a further part of the head portion engaging the closure member and with the tail portion engaging the diaphragm.

10. The valve claimed in Claim 9, which is a suction demand valve and which includes an urging means for urging the closure member into closing engagement with the flow opening defining member, with the closure member being on one side of the flow opening defining member and the diaphragm on the other side thereof, the head portion engaging the closure member via the opening.

11. The valve claimed in Claim 9, in which the head portion engages the closure member indirectly, and which includes a pin located between the head portion and the closure member.

12. The valve claimed in Claim 9, in which the head portion is substantially flat and the tail portion is curved.

13. The valve claimed in Claim 9, which includes a pair of spaced lugs fast with the diaphragm for locating the tail portion of the displacing member

14. The valve claimed in Claim 9, which includes a locating formation about the opening for locating the head portion adjacent the opening.

15. A suction demand valve substantially as described in the specification with reference to the accompanying drawings.

16. A high pressure gas cylinder in combination with a suction demand valve as claimed i any one of Claims 1 to 8 inclusive or 15.