GB2028466A

GB2028466A - A Fluid Pressure Relief Valve

Info

Publication number: GB2028466A
Application number: GB7909851A
Authority: GB
Original assignee: Burnett and Rolfe Ltd
Current assignee: Burnett and Rolfe Ltd
Priority date: 1978-06-01
Filing date: 1979-03-21
Publication date: 1980-03-05
Also published as: DK231379A; GB2028466B; GB2022215A

Abstract

The valve includes a closure member (4), and variable biasing means to bias the closure member into the closed position with the biasing means including a third order lever system formed by a lever (19), a bias weight (11), a movable fulcrum (23) and a valve operating member (21, 22) arranged with the valve operating member engaging the lever between the fulcrum and the bias weight. The biasing means are arranged so that the lever, the bias weight and the fulcrum are movable and their positions are infinitely variable with respect to the valve operating member to provide an infinitely variable pressure at which the relief valve vents fluid. The pressure is varied by rotation of a pinion (23) between a fixed rack (27) and a rack (20) on the lever to cause the fulcrum to move along a slot (28) and the lever and the weight to move relative to the valve operating member. <IMAGE>

Description

1

SPECIFICATION

Improvements Relating to a Fluid Pressure Relief Valve This invention relates to a fluid pressure relief valve including a valve closure member and biasing means acting on the closure member to bias it into its closed position, the biasing means being adjustable to vary the pressure at which the valve closure member opens to vent fluid.

Previously, such biasing means have included a third order lever having one end of the lever pivotally connected to a body of the valve, and a weight slidingly attached to the lever so that the weight is movable along the lever towards and away from the pivot to vary the pressure at which the valve closure member moves to vent fluid. In practice, with this type of valve, the range of adjustment between the two extreme positions of the weight provides a variation of the relief pressure of the order of 2A.

Another biasing means which has been used previously includes a pivoted lever in which the position of the pivotal connection between the lever and the valve body has two discreet positions on the lever.

When this is combined with changes in the location of the weight on the other end of the lever an adjustment ratio of the order of 2.5:1 can be achieved.

Previously, we have manufactured a valve in which the biasing means has included a lever having a weight permanently fixed to it at a constant distance from the pivotal connection between the operating member of the valve and the lever. The pivot forming the fulcrum of the lever is movable and may be fixed in any position along its length of travel. This valve has an adjustment ratio of the order of 3: 1.

Of course, with all these types of valve the range of adjustment of the relief pressure can be changed to some extent by exchanging the weight for one having a different mass but this is inconvenient and the weights of different mass are easily mislaid.

According to this invention a fluid pressure relief valve includes a valve closure member and biasing means to bias the closure member into the closed position, the biasing means including a third order lever system formed by a lever, a bias weight, a movable fulcrum, and a valve operating member the biasing means being arranged with the valve operating member engaging the lever between the fulcrum and the bias weight, the arrangement being such that the lever, the bias weight and the fulcrum are movable and their positions infinitely variable with respect to the valve operating member to provide an infinitely variable pressure at which the relief valve vents fluid.

The bias means may be arranged so that, the lever, the bias weight and the fulcrum are moved as a whole with the distance between the bias weight and the fulcrum remaining constant. In this case, the lever is preferably formed as a GB 2 028 466 A 1 screwthreaded shaft having the bias weight secured to one end and a pivot block journaled onto the other end, the pivot block carrying the fulcrum, and the threaded shaft being screwed into a nut engaging the valve operating member.

With such an arrangement, as the screwthreaded shaft and bias weight are rotated, the shaft, bias weight and pivot block move with respect to the nut engaging the valve operating member to move both the weight and the pivot with respect to the valve operating member.

Preferably the distance between the fulcrum and the bias weight is also infinitely variable. This means that the distance between the bias weight and the valve operating member, the distance between the valve operating member and the fulcrum, and the distance between the bias weight and the fulcrum are all variable and this results in a very much greater range of operating pressures at which the relief valve will vent fluid.

In this case the lever preferably includes a rack and the fulcrum preferably includes a pinion meshing with the rack and arranged so that it can be moved in position with respect to valve operating member. The arrangement to enable the pinion to be moved with respect to the valve operating member preferably includes another rack mounted on the valve in a fixed position facing the rack on the lever with the pinion meshing with both racks, as the pinion is rotated the pinion moves with respect to the other rack and the lever moves with respect to both the other rack and the pinion.

It is preferred that the bias means are arranged so that, as the lever, the bias weight and the l 00 fulcrum are moved, contact between the valve operating member and the lever is maintained continuously, whereby a bias force is exerted continuously on the valve operating member during adjustment. This ensures that fluid under pressure is not vented inadvertantly during adjustment of the relief pressure.

Preferably the valve includes a body divided into two chambers with the valve closure member arranged to control communication between the two chambers. When the valve body is arranged in this way the fluid vented upon movement of the valve closure member, passes from one of the chambers into the other. The fluid entering the other chamber may be vented from an outlet of the other chamber but preferably the outlet of the other chamber is arranged to be connected to a pipe to enable the fluid to be collected or recycled or, alternatively, conveyed to a remote location, for example outside a building, before being vented to the atmosphere.

The fluid pressure relief valve in accordance with this invention has particular application in the brewing and foodstuff processing industry in which the valve is used to control the pressure applied to the contents of a tank or other container. For example, in the brewing industry the valve may be connected to a tank which is arranged to hold fermented beer.

In this application the tank and-valve are first 2 GB 2 028 466 A 2 sterilised with steam and then the tank is flushed with carbon dioxide gas and pressurised so that the tank is filled with inert carbon dioxide gas held under a particular pressure which is determined by the setting of the relief valve. The fermented beer, is then introduced into the pressurised container and as it is introduced, the pressure relief valve maintains the same particular pressure in the tank by venting carbon dioxide to compensate for the beer pumped into the tank. The pre-pressurisation of the tank prevents the fermented beer from foaming and merely filling the tank with fob. Once the filling of the tank has been completed the adjustment of the relief valve may be changed for example to provide a lower pressure under which to continue the process.

Since this valve has particular application in the brewing and foodstuff industry it is preferred that the entire valve is manufactured from stainless steel with neoprene or other elastomeric.

sealing material on the seating surfaces of the valve closure member, the elastomeric material being selected so that it is not adversely affected by a steam sterilising operation.

Two particular examples of a pressure relief valve in accordance with this invention will now be described with reference to the accompanying drawings, in which, Figure 1 is a partly sectioned side elevation of the first example; Figure 2 is a partly sectioned side elevation of the second example; and Figure 3 is a scrap section on the line 111-111 shown in Figure 2.

The first example of pressure relief valve comprises a biasing means shown generally as 1 and a valve means. The valve means is entirely conventional and it includes a body formed by an upper chamber 2 and a lower chamber 3, a valve closure member 4 including a fluted stem 5 and a sealing gasket 6, and a valve operating member 7 which engages with the valve closure member 4 and is a sliding fit through a gland 8 in the top wall of the chamber 2. In use, when the fluid pressure in the lower chamber 3 beneath the valve closure member 4 builds up to such an extent that the upwaros force on the valve closure member 4 exceeds the downwards force exerted by the biasing means 1 the closure member 4 lifts to allow fluid to escape from the lower chamber 3 115 into the upper chamber 2. The upper chamber 2 includes an outlet pipe 9 to enable vented fluid to be collected and re-cycled or vented to the atmosphere at a remote location.

The biasing means 1 comprises a screwthreaded shaft 10, a bias weight 11 fixed onto one end of the shaft 10, and a pivot block 13 rotably journaled on to the other end of the screwthreaded shaft 10. The pivot block 13 is arranged to accommodate a journaled pin 14 which passes through the block 13 and engages the sides of a pair of slots 15 formed in opposite sides of a U-shaped support frame 16, only one side of which is shown in the drawing. The nut 12 receives a pin 17 which is guided in a pair of slots 130 18 again formed between the opposite sides of the U-shaped frame 16, so that it is held directly above the valve operating member 7. Vertical movement of the valve operating member and the nut 12 causes a small horizontal movement of the journaled pin 14 along the slots 15.

To vary the bias force applied by the bias means 1 through the nut 12 on to the member 7 the bias weight 11 and the shaft 10 are rotated to screw or unscrew the shaft 10, with respect to the nut 12 and so move the shaft 10, the bias weight 11 and the pivot block 13 axially with respect to the nut 12.

Preferably the biasing means 1 includes an indexing mechanism, not shown, attached to the pin 14 to indicate the pressure at which the relief valve is set to vent fluid under pressure.

This example of a valve has an adjustment ratio of the bias means of 4:1 but, in practice, it is possible to arrange for the adjustment ratio to be as high as 6:1 using valves in accordance with this invention.

The second example has a generally similar valve body to the first example and corresponding parts have been given the same reference numerals. The biasing means 1 comprises a lever 19 having a rack 20 formed on its top edge towards one end and the bias weight 11 attached to the opposite end. The lever 19 engages a freely rotating runner or journal 2 formed by a ball-race mounted in a U-shaped saddle 22. The saddle being coupled to the valve operating member 7 by a screwthreaded shaft to allow for vertical adjustment. The rack 20 is arranged to mesh with a spur gear pinion 23 which is located on a square shaft 24 connected to an adjusting knob 25.

The biasing means 1 includes a support frame 26 having a generally inverted U-shape with a rack 27 forming the upper member of the support frame 20. The pinion 23 meshes with both racks 20 and 27 and the shaft 24 passes through slots 28 in both sides of the frame 26.

As the pinion 23 is rotated it travels along the rack 27 which is fixed relative to the valve operating member 7, and the [ever 19 moves over the runner or journal 21 twice the distance travelled by the pinion 23 so varying the leverage of the bias weight 11 with respect to the valve operating member 7.

The adjusting knob 25 and shaft 2,4 are provided with a friction pad and locking nut 30 to enable the setting to be fixed after adjustment. Preferably the biasing means 1 includes an indexing arrangement or graduated scale attached to the support frame 26 to indicate the pressure at which the relief valve is set to vent fluid under pressure.

With this example since, the length of the lever, the distance from the bias -weight to the valve operating member, and the distance between the valve operating member and the fulcrum are all adjustable a significantly greater range of adjustment is provided for the pressure at which the relief valve vents fluid than is obtainable with previous valves.

7 3 GB 2 028 466 A 3 This example of a valve has an adjustment ratio of the bias means of 7:1 but it is possible, in practice, to arrange for the adjustment ratio to be 45 as high as 9:1 using valves in accordance with this invention.

Claims

1. A fluid pressure relief valve including a valve closure member and biasing means to bias the closure member into the closed position, the biasing means including a third order lever system formed by a lever, a bias weight, a movable fulcrum and a valve operating member, the biasing means being arranged with the valve operating member engaging the lever between the fulcrum and the bias weight, the arrangement being such that the lever, the bias weight, and the fulcrum are movable and their positions are 60 infinitely variable with respect to the valve operating member to provide an infinitely variable pressure at which the relief valve vents fluid.

2. A valve according to claim 1, in which the lever, the bias weight, and the fulcrum are movable as a whole with the distance between the bias weight and the fulcrum remaining constant.

3. A valve according to claim 1 or 2, in which the lever is formed as a screwthreaded shaft having the bias weight secured to one end and a pivot block journaled on to its opposite end, the pivot block carrying the fulcrum, and the threaded shaft being screwed into a nut forming the valve operating member.

4. A valve according to claim 3, in which the pivot block includes a pin and the biasing means includes a slotted frame extending alongside the screwthreaded shaft, the pin engaging the sides of the slot in the frame to form the fulcrum.

5. A valve according to claim 3 or 4, in which the nut is held between the opposite sides of a frame and so prevented from rotating with the screwthreaded shaft.

6. A valve according to claim 1, in which the 85 distance between the fulcrum and the bias weight is infinitely variable.

7. A valve acording to claim 6, in which the lever includes a rack and the fulcrum includes a pinion meshing with the rack and arranged so that it is movable in position with respect to the valve operating member.

8. A valve according to claim 7, in which the biasing means includes a frame carrying another rack which faces the rack on the lever with the pinion meshing with both racks, in use, rotation of the pinion moving the pinion with respect to the other rack and hence to the valve operating member, and,moving the lever with respect to both the other rack, and hence the valve operating member, and the pinion.

9. A valve according to any one of the preceding claims, in which the bias means are arranged so that, as the lever, the bias weight and the fulcrum are moved, contact between the valve operating member and the lever is maintained continuously, whereby a bias force is exerted continuously on the valve operating member during adjustment of the relief pressure.

10. A valve according to any one of the preceding claims, in which the valve includes a body divided into two chambers with the valve closure member arranged to control communication between the two chambers.

11. A valve according to any one of the preceding claims, which is manufactured from stainless steel with neoprene or other eiastomeric sealing material on the seating surfaces of the valve closure member, the elastomeric material being selected so that it is not adversely affected by a steam sterilising operation.

12. A valve according to any one of the preceding claims, further includes indexing means to indicate the pressure at which the relief valve is set to vent fluid under pressure.

13. A valve according to claim 1, constructed -substantially as described with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by the Courier Press, Leamington Spa, 1980. Published by the Patent Office, 25 Southampton Buildings, London, WC2A 1 AY, from which copies may be obtained.