GB2107433A - Protector valve - Google Patents

Abstract

This valve isolates from the effect of excess fluid pressure a pressure sensitive device connected to bore 8, when pressure from a fluid supply connected to bore 6 rises above a pre-determined level so that the fluid pressure force on piston 34 overcomes the effort of spring 48 and closes the valve member 30, 38 against the valve seat 22. The valve seat and valve member are both provided on a cartridge 12 which is removably screwed to body 4 so that the valve seat and member are removable simultaneously with the cartridge from the body without disturbing connections of the pressure sensitive device and fluid supply to the bore 8 and 6 respectively. <IMAGE>

Description

SPECIFICATION Protector valve This invention concerns protector valves. Protector valves are used to connect a source of fluid pressure to a pressure sensitive device which can be damaged if subjected to a fluid pressure peak of a value exceeding that which the device is intended to withstand. The protector valve closes automatically in response to the fluid pressure exceeding a pre-determined maximum, thus isolating the device from the pressure source so that the device is not subjected to damaging higher pressure; whereas the valve opens automatically in response to the fluid pressure abating below the said maximum. Pressure sensitive devices protected in this way may be devices to measure fluid pressure, for example pressure gauges or pressure switches.

According to the invention a protector valve comprises a body, first and second passage means provided in the body, a valve seat and a valve member both mounted in the body in a manner permitting their removal from the said body, the valve member being automatically moveable relatively to the seat in response to fluid pressure developed in the first passage means to open and close a route between said valve member and seat, and the arrangement being such that when said fluid pressure is below a pre-determined value the first and second passage means are in communication through said open route and when the fluid pressure attains at least said pre-determined value the route is closed and communication between the first and second passage means is interrupted.

The fact that the valve seat and valve member are both removable can have the advantage of facilitating cleaning and/or maintenance of the seat the valve member and their replacement by a substitute if either becomes worn.

The first and second passage means may both be formed in the body, an element provided with the valve seat may be removably mounted on the body, and this element may also carry the valve member.

Thus the valve seat and valve member may be removed from the body by removing the element, without disturbing the first and second passage means. Thus a connection between, for example, a pressure fluid supply line and the first passage means and a connection between, for example, a pressure gauge and the second passage means need not be disturbed when the valve member and seat are removed, The valve member may be moved to close the route in response to the fluid measure acting on a piston in opposition to resilient effort.

The invention will now be further described, by way of example, with reference to the accompanying drawing which is a diagrammatic view partly in section of an embodiment of a protector valve formed according to the invention in a closed position.

The protector valve indicated generally at 2 comprises a body 4 formed at each end with internally threaded bores 6 and 8 which can be conical as shown. Bore 6 is for connection to a source of pressure fluid, for example, a pressure fluid supply line, and bore 8 is for connection to a pressure sensitive device, for example, a pressure gauge.

The body is also formed with an internally threaded cavity 10 into which is removably screwed an end 12a of an element or cartridge 12 bearing on a sealing ring 14 on a shoulder of the cavity wall.

The bores 6 and 8 lead into cavity 10 through further boxes 16 and 18.

Cartridge end 1 2a is formed with a bore 20 opening at one end into a conical recess forming a valve seat. Sliding in bore 20 is a rod 24 formed with an annular groove containing an O-ring seal 26. Rod 24 is waisted at 28, has a frust-conical part 30 (which may have a cone angle similar to that of valve seat 22), and an extension 32 integral with a piston 34 from which a projection or pip 3 extends. Between the part 30 and piston 34 is a resilient, sealing O-ring 38 surrounding the extension 32.

Bore 18 opens to an annular groove 40 in the end part 12a. Also formed in that end part is a bore 42 extending from the groove 40 at one end to the bore 20 and valve seat 22 at its other end.

Above end part 12a, the cartridge 12 is formed with a compartment 44 into which bore 20 opens.

This compartment is closed by a screw-in cover 46 bracing one end of a helical compression spring 48 pressing at its other end on loose plate 50 applied to an end of the rod 24 to urge a valve member comprised of part 30 and ring 38 away from the valve seat 22.

The insertion of end part 1 2a in the cavity 10 forms a chamber 1 ova in the end of that cavity. The piston 34 is located in the chamber 10a which has side walls well clear of the piston periphery. Bore 16 opens in to the chamber 10a adjacent the chamber's end wall 52 acting as a stop for the pip 36 which not only limits the extent to which the valve member 30,38 can be moved clear of the valve seat 22 by the pressure of spring 48 but also ensures face 34a of the piston is exposed to the fluid pressure in bores 6, 16.

The effective surface area of face 34b of the piston is reduced by the extension 32 and is thus less than that of the face 34a. Because of this the fluid pressure delivered by bores 6, to chamber 10a produces a resultant force acting to urge the piston 34 in opposition to the spring 48. The aforesaid resultant force is a function of the fluid pressure in the bores 6, 16. When the pressure in bores 6, 16 is below a pre-determined value, the aforesaid resuitant force on the piston 34 does not exceed the force of the spring 48 and thus the valve member 30,38 is pushed off the seat 22 to leave a gap or route between the valve member and seat so that bore 6 and bore 8 are in communication through the open route.But when the pressure in bores 6, 16 attains at least the pre-determined value, the aforesaid resultant force on piston 34 overcomes the force of spring 48 and presses the valve member onto the seat 22 to close the route. Thus bore 8 is isolated from bore 6 so that further pressure variation in bore 6 is not communicated to bore 8 until the pressure in bore 6 falls below the pre-determined value which enables the route to be opened again.

The pre-determined fluid pressure value at which the valve closes can be varied by altering the force exerted by spring 48 by varying the screwed-in position of the cover 46.

The cartridge 12 can be unscrewed from cavity 10 carrying with it the rod 24 so that the valve seat and valve member are both removed together from the body 4 without disturbing connections attached to bores 6 and 8.

Neglecting the connections to bore 6 and 8 in the valve described above, the places where fluid leakage from the body 4 can accidentally occur are substantially reduced to one, namely between the sidewall of cavity 10 and the cartridge end 12a. This is less than in known protector valves.

In the valve described above, the arrangement permits there to be a marked difference between the effective surface areas of piston faces 34a and 34b.

Accordingly for a given fluid pressure in chamber 1 Oa the aforesaid resultant force can be relatively high causing rapid valve closure when the pressure rises to the predetermined value.

Additional sealing may be effected by means of a bellows seal or a diaphragm seal arrangement. Such additional sealing may be provided, for example, to further isolate the bore 20 from all or a greater part of the compartment 44.

CLAIMS (Filed 21 Sept 82) 1. A protector valve comprising a body, first and second passage means provided in the body, a valve seat and a valve member both mounted in the body in a manner permitting their removal from the said body, the valve member being automatically moveable relatively to the seat in response to fluid pressure developed in the first passage means to open and close a route between said valve member and seat, and the arrangement being such that when said fluid pressure is below a pre-determined value the first and second passage means are in communication through said open route and when the fluid pressure attains at least said pre-determined value the route is closed and communication between the first and second passage means is interrupted.

2. A protector valve as claimed in Claim 1, in which the valve seat is on an element on which the valve member which co-operates with the valve seat is mounted, said body has a cahmber, the first and second passage means each open into the chamber through a wall of said chamber, the valve member and seat are simultaneously movable with the element which is removably mounted in said chamber so that when the route is open the route extends through the chamber from one said passage means to the other.

3. A protector valve as claimed in claim 2, in which the element is in detachable screw threaded engagement with screw thread on said wall of the chamber.

4. A protector valve as claimed in claim 2 or claim 3, in which a piston connected to the valve members is disposed in said chamberforfluid pressure developed in the first passage means to act on the piston to urge the valve member in the route closing direction towards the valve seat in opposition to effort applied by resilient means to the valve member.

5. A protector valve as claimed in any one of claims 2 to 4, in which said route comprises third passage means disposed in the element and open at one end at the valve seat, and said third passage means being open at the other end in a groove formed in and surrounding the element into which groove the second passage means opens at said chamber wall.

6. A protector valve as claimed in any one of claims 2 to 5, in which the valve member is mounted on a rod sliding in a bore in the element.

7. A protector valve substantially as herein before described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (7)

**WARNING** start of CLMS field may overlap end of DESC **. The pre-determined fluid pressure value at which the valve closes can be varied by altering the force exerted by spring 48 by varying the screwed-in position of the cover 46. The cartridge 12 can be unscrewed from cavity 10 carrying with it the rod 24 so that the valve seat and valve member are both removed together from the body 4 without disturbing connections attached to bores 6 and 8. Neglecting the connections to bore 6 and 8 in the valve described above, the places where fluid leakage from the body 4 can accidentally occur are substantially reduced to one, namely between the sidewall of cavity 10 and the cartridge end 12a. This is less than in known protector valves. In the valve described above, the arrangement permits there to be a marked difference between the effective surface areas of piston faces 34a and 34b. Accordingly for a given fluid pressure in chamber 1 Oa the aforesaid resultant force can be relatively high causing rapid valve closure when the pressure rises to the predetermined value. Additional sealing may be effected by means of a bellows seal or a diaphragm seal arrangement. Such additional sealing may be provided, for example, to further isolate the bore 20 from all or a greater part of the compartment 44. CLAIMS (Filed 21 Sept 82)

1. A protector valve comprising a body, first and second passage means provided in the body, a valve seat and a valve member both mounted in the body in a manner permitting their removal from the said body, the valve member being automatically moveable relatively to the seat in response to fluid pressure developed in the first passage means to open and close a route between said valve member and seat, and the arrangement being such that when said fluid pressure is below a pre-determined value the first and second passage means are in communication through said open route and when the fluid pressure attains at least said pre-determined value the route is closed and communication between the first and second passage means is interrupted.

2. A protector valve as claimed in Claim 1, in which the valve seat is on an element on which the valve member which co-operates with the valve seat is mounted, said body has a cahmber, the first and second passage means each open into the chamber through a wall of said chamber, the valve member and seat are simultaneously movable with the element which is removably mounted in said chamber so that when the route is open the route extends through the chamber from one said passage means to the other.

3. A protector valve as claimed in claim 2, in which the element is in detachable screw threaded engagement with screw thread on said wall of the chamber.

4. A protector valve as claimed in claim 2 or claim 3, in which a piston connected to the valve members is disposed in said chamberforfluid pressure developed in the first passage means to act on the piston to urge the valve member in the route closing direction towards the valve seat in opposition to effort applied by resilient means to the valve member.

5. A protector valve as claimed in any one of claims 2 to 4, in which said route comprises third passage means disposed in the element and open at one end at the valve seat, and said third passage means being open at the other end in a groove formed in and surrounding the element into which groove the second passage means opens at said chamber wall.

6. A protector valve as claimed in any one of claims 2 to 5, in which the valve member is mounted on a rod sliding in a bore in the element.

7. A protector valve substantially as herein before described with reference to the accompanying drawing.