GB2182248A

GB2182248A - Inlet valve assembly for a demand regulator divers valve

Info

Publication number: GB2182248A
Application number: GB08524713A
Authority: GB
Inventors: Donald Lynn Rodocker
Original assignee: Gas Services Offshore Ltd
Current assignee: Gas Services Offshore Ltd
Priority date: 1985-10-07
Filing date: 1985-10-07
Publication date: 1987-05-13
Also published as: GB8524713D0; GB2182248B

Abstract

The present invention provides an inlet valve assembly for a demand regulator divers valve having a valve body 21 to 23, an inlet duct 24, an outlet duct 25 and a valve member 26 in the valve body moveable between a first position in which the inlet duct 24 and outlet duct 25 are in gas flow communication and a second position in which there is no communication between said ducts, the assembly being characterised in that forces exerted by 24 inlet gas supply pressure on the valve member are substantially balanced such that relatively small forces are required to move the member between the said two positions. For example the inlet valve may be held closed by a light spring load acting on the inlet valve member. A preferred inlet valve assembly has an essentially dumbell shaped inlet valve member, and inlet duct pressure acts in a cavity 36 defined between the dumbell end portions and a surrounding valve body portion, and outlet duct pressure (relatively low) acts at the outer end surface of each end portion. <IMAGE>

Description

SPECIFICATION Inlet valve assembly for a demand regulator divers valve A demand regulatordivers valve may be used to supply breathing gas from a high pressure supply to a diver, at ambient pressure, "on demand". Such demand regulator divers valves in general supply gas whilst a diver produces a pressure drop in thevalve by inhalation, and these devices are known in the prior art (for example UK Patent Application No.

2132489 and US Patent No.3680556). A demand re gulator divers valve of the type described in UK Patent Application No.2132489 is illustrated in accompanying Figures 1 and 2 and described below.

High pressure breathing gas, e.g. at 10 to 20 bar over ambient pressure, is supplied to the inlet nipple 1. The gas pressure exerts a force on the inlet valve mem ber 2 which is counter balanced by the spring 3.

Different gas supply pressures are accommodated by adjusting the loading on the spring by means of a threaded adjustment knob 4. On inhalation the diver produces a small pressure drop in duct 5 and within regulatorchamber6which allowsthediaphragm7 to be driven inwards by external ambient pressure 8.

The resulting movement of yoke lever 9 bearing on the diaphragm backing plate 10 causesthe inlet valve member2to lift off its seating on the inlet nipple 1, allowing gasto pass to the divervia chamber6and duct 5.

Priorartdemand regulatordiversvalvesofthis type have the disadvantage that the full inlet pressure must be counterbalanced bythe spring. Fine adjustment of the spring loading is essential to ensure correct operation of the valve: if spring load is too high a large force will be required to liftthe inlet valve member, requiring considerable effort on the part of the diver during inhalation; if the load is too small breathing gas will continuouslyleak("free flow") through the regulator valve. Heavy duty springs are needed to hold the inlet valve closed againsta high inletgas supply pressurewith consequential lack of sensitivity of load adjustment.

The present invention provides an inlet valve assembly for a demand regulator divers valve having a valve body, an inletduct, an outletductand avalve member in the valve body moveable between a first position in which the inlet duct and outlet duct are in gas flow communication and a second position in which there is no communication between said ducts, the assembly being characterised in that forces exerted by inlet gas supply pressure on the valve member are substantially balanced such that relatively small forces are required to move the member between the said two positions. For example the inlet valve may be held closed bya light spring load acting on the inlet valve member.

A preferred inlet valve assembly has an essentially dumbell shaped inlet valve member moveable within the valve body between the first and second positions wherein, in the "closed" position of the valve, inlet duct pressure (relatively high) acts in a cavity defined between the dumbell end portions and a surrounding valve body portion, and outlet duct pressure (relatively low) acts at the outer end surface of each end portion.

The invention also provides a demand regulator divers valve having an inlet valve assembly as described above.

The invention will now be described in detail, by way of example only, with reference to the accompanying drawings, in which: Figure 3 is a cross sectional representation of an assembly according to the invention; and Figure 4 is a cross sectional representation of the Figure 3 assembly attached to a demand regulator divers valve.

Figures 3 and 4 show an inletvalve assembly 20 comprising valve body portions 21,22,23, an inlet duct 24, an outletduct25 and an essentiallydumbell shaped valve member 26. The valve body portions 21,22, 23 may be disassembledforservicing purposes; sealing between valve body portions is established by means of O-ring 27 and valve seat 28. In this embodiment valve body portion 22 is adapted for direct connection to a demand regulator divers valve (see Figure 4) and an 0being 29 seal istherefore provided. Iniet duct 24 is adapted for direct connec- tiontoa breathing gas supply.

Valve member26 has end portions 30 and 31,a valve stem 32 attached to the outer end of portion 31 and a passage 33 providing communication between the external surface of the stem 32 and the end surface of portion 30.

End portion 30 isaslidablefitinsidea boreformed by surrounding valve body portion 23, and a sliding seal is provided by O-ring 34; a cavity 35 is defined between valve body portion 23 and end portion 30.

End portion 31 can sealingly abut valve seat 28.

A cavity 36 is defined between the end portions 30 and 31 and surrounding valve body portion 23. The cavity is in gas flow communication with inlet duct 24 by passageways 37.

When in use, inlet pressure acts in inlet duct 24, passageway 37 and cavity 36; a force is exerted on the inner surfaces of the valve end portions 30,31.At the same time pressure in outlet duct 25 acts in cavity 35. The forces acting on inlet valve member 26 are essentially balanced - in the exemplified case a small net force is exerted in a direction to lift the valve end portion 31 off the valve seat 28 because pressure in cavity 36 is acting over a slightly larger area in that direction by virtue of the small step 39 in valve body portion 23.

As shown in Figure 4, when the inletvalve assembly of Figure 3 is used in conjunction with a demand regulator divers valve to supply breathing gas from a high pressuresupplyto a diver, alight- load spring 40 can be used acting on the valve stem 32 to maintain the inlet valve 20 normally closed.

When the pressure in duct 5 is reduced, e.g. bythe diver inhaling,the diaphragm 7 and backing plate 10 move to actuate the yoke lever 9, all owing lifting of the inlet valve from the seat and causing breathing gas to pass fro inlet duct 24through passageways 37 and cavity 36 to outlet duct 25 and thence via duct 5 to the diver.

The inlet valve assembly of the present invention can advantageously be used with a demand regula tordiversvalveto reduce the effort expended bya diver in breathing. Such an inlet valve may be provided separately as an assemblyforfitting to such a demand regulator, or it may be integrally formed with the regulator.

Whilstthe particular embodiment has been described as having, in use, a slight inlet valve biastowards the "open position" the configuration of the inlet valve assembly could be modified if desired to provide a bias in the opposite direction. This could,for example, be achieved by providing a step or steps 39 in the valve body portion 23 which serve to increase the bore diametertowardsthe closed (cavity 35) end.

Equally an inlet valve assembly according to the invention could be completely balanced with no net force in eitherthe "open" or "closed" directions.

An assembly according to the invention is simple and cheap to manufacture, is convenientto fit and service and does not rely on springs or other resilient means within the assembly to balance the forces exerted by inlet gas pressure.

Claims

1. An inletvalveassemblyfora demand regulator divers valve having a valve body, an inlet duct, an outlet duct and a valve member in the valve body moveable between a first position in which the inlet duct and outlet duct are in gas flow communication and a second position in which there is no communication between said ducts, the assembly being characterised in that forces exerted by inlet gas supply pressure on the valve member are substanti- ally balanced such that relatively small forces are required to move the member between the said two positions.

2. An inletvalve assembly according to claim 1 having an essentially dumbell shaped inlet valve member moveable within the valve body between the first and second positions wherein, in the "closed" position of the valve, the inlet duct communicates with a cavity defined between the dumbell end portions and a surrounding valve body portion, and the outlet duct communicates with the outer end surface of each end portion.

3. A demand regulator divers valve having an inlet valve assembly according to claim 1 or 2.

4. An inlet valve assembly substantially as hereinbefore described with reference to Figures 3 and 4 ofthe drawings.

5. A demand regulator divers valve having an inlet valve assembly substantially as herein before described with reference to Figures 3 and 4 of the drawings.

5. A demand regulator divers valve having an inlet valve assembly substantially as herein before described with reference to Figures 3 and 4 ofthe drawings.

Amendments to the claims have been filed, and have thefollowing effect: *(a) Claims 1 to 5 above have been deleted.

*(b) New claims 1 to 5 have been filed asfollows:

1. An inletvalvefora demand regulatordivers valve of the type having a regulator valve body, a diaphragm forming a wall portion of a chamber in the body, a regulator valve inlet duct, a regulator valve outlet duct and means operable in response to def lection of the diaphragm to actuate an inlet valve, the inlet valve having a valve body, an inletductdirectly connectable to a breathing gas supply, an outlet duct and an essentially dumbell shaped inlet valve member movable within the valve body between a first position in which the inlet duct and outlet duct are in gas flow communication and a second position in which there is no communication between said ducts, wherein in the "closed" position of the valve the inlet duct communicates with a cavity defined by the inner surfaces of the valve member between dumbell end portions and a surrounding valve body portion, and the outlet duct communicates with outer end surfaces of each dumbell end portion, and being characterised in that the inlet valve comprises an assembly, connectable as a unit directly by its outlet duct to the inlet duct of a demand regulatordivers valve ofthe said type in place of the conventional inlet valve and further characterised in that said inlet and outlet ducts of the assembly are axially aligned.

2. An inletvalve assembly according to claim 1 comprising first and second members together defining a valve body member, said valve body member having an inletductthrough said first member and an outlet duct through said second member, said ducts being axially aligned, a chamber defined within said valve body member, a bell member locatedwithin said chamber with a closed end towards said inlet duct and an open end towards said outlet duct, a valve seat on said open end of said bell member, said valve seat being towards said outlet duct, an elongate dumbell shaped valve member mounted with one dumbell end within said bell memberforming a sealing sliding fit with the inner surface of said bell memberandtheotherdumbell end sealingly seating on said valve seat, said valve body member and said bell member defining a first annularcavityforming part of said inlet duct between the inner surface of the valve body member and the outer surface ofthe bell member and said bell member and said valve member defining a second annular cavity between the inner surfaces ofthe valve member between the dumbell end portions and the inner surface ofthe surrounding portion of the bell member, said two annular cavities being coaxial and being in gas flow communication via at least one radial passagewaythrough said bell member, a valve stem extending from said valve memberto terminate beyond said outlet, an axial bore in said valve stem and said valve memberopening at one end in the closed end of said bell shaped member beyond said one dumbell end portion and at its other end on the external surface of the stem and providing pressure equalisation between a third cavity between the inner end surface of said bell member and the outer surface of said one dumbell end portion and the outlet, said valve stem at the end remote from the valve portion being connectable to means operable to actuate said inlet valve.

3. An inletvalve as defined in claim 1 or2remov- ably connected externally ofthe inlet duct of a demand regulator divers valve in place of the conventional regulatorinletvalve.

4. An inlet valve assembly substantially as hereinbefore described with reference to Figures 3 and 4 of the drawings.