WO1994027072A1

WO1994027072A1 - Safety devices

Info

Publication number: WO1994027072A1
Application number: PCT/GB1994/001027
Authority: WO
Inventors: Gordon W. Mclean
Original assignee: RICHARD THRELFALL GROUP Ltd
Current assignee: RICHARD THRELFALL GROUP Ltd
Priority date: 1993-05-12
Filing date: 1994-05-12
Publication date: 1994-11-24
Anticipated expiration: 1995-11-12
Also published as: GB9309755D0; AU6654494A

Abstract

A safety device is provided comprising a body (1) defining a flow path (2, 3) a closure member (7) being situated within the flow path, there being biasing means (9) bearing against the closure member and fusible or corrodible linking means (12) wherein, in an emergency situation, the linking means melts or corrodes, causing the closure member to change an operating status of the device. The device may be used as a fluid control valve which closes automatically in the event of an emergency.

Description

SAFETY DEVICES

The invention relates to safety devices and particularly, but not exclusively, to safety devices for use in conjunction with fluid control valves or flow lines.

In U.K. Patent application GB 2.231.64U there is descri bed a valve which is fail safe in the event of a fire. The valve comprises a rotatable ball arrangement having a cylindrical passageway formed therein. The valve has a first, open configuration with the passageway in line with a fluid flow path, and a second configuration in which the valve is closed. In the event of a fire, a meltable valve seating arrangement to one side of the ball, and a spring, bearing against the opposing side of the ball co-operate to bring about a degree of re-sealing.

A disadvantage which has been discovered with the above type of valve is that in some circumstances following a fire, the ball may stick in the open position, or residual particles of the seating arrangement may hinder re- sealing. In such circumstances, the valve is susceptible to leakage.

Accordingly, a first aspect of the invention provides a safety device comprising :

a body defining a flow path a closure member situated within the flow path; biasing means bearing against the closure member; and fusible or corrodible linking means wherein, in an emergency situation, the linking means melts or corrodes, causing the closure member to change an operating status of the device.

Preferably, the safety device performs an automatic shut-off function and, in ti e emergency situation, the operating status changes from an open configuration, in which fluid is allowed to flow along the flow path, to a closed configuration in which the flow path is obstructed.

Preferably, the valve body comprises an internal passageway, forming the flow path, and a fixed member situated within the passageway, the fixed member having a solid portion and one or more apertures, to permit fluid flow through the one or more apertures when in the open configuration, the closure member being of a complimentary construction to that of the fixed member, such that in the closed configuration, the fixed member and the closure member co-operate to obstruct the flow path.

Preferably, both the fixed member and the closure member are positioned transversely with respect to the fluid flow path.

A circlip. or similar fixing means, may be provided for retaining the biasing means in position within the body.

Preferably, in the open configuration, the fixed member and the closure member are held apart by the linking means and. in the closed configuration, are urged towards each other by the biasing means. - .1 -

Preferably, the closure member is a plate-like member having one or more apertures formed therein. The closure member may comprise a circular washer and the fixed member may comprise a solid central portion suspended within the passageway and joined to the rest of the valve body by at least two bridging portions.

Alternatively, the closure member may be a closure valve. The closure valve preferably comprises a connecting rod and a head.

The biasing means encircle the connecting rod and bear against the head such that, upon the occurrence of an emergency, the head is brought into contact with the fixed member so as to obstruct the flow path.

Guide means may be provided for guiding movement of the closure member when changing from the open configuration to the closed configuration. In an alternative arrangement, the biasing means may encircle the connecting rods, bear against the fixed member and be arranged to act against the guide means so as to move the valve and change the operating status of the device in an emergency. The biasing means may comprise a compression spring or one or more disc springs.

The guide means may be a part of the closure valve.

The safety device may form part oi^' a fluid flow line.

Alternatively, the safety device may form a part of a fluid control valve. Preferably, the fluid control valve additionally comprises a valve seat and a valve member abutting the valve seat, the biasing means bearing against the valve member and the valve member being movable from a closed position, to an open position, in which fluid flow can take place along the flow path through a passage in the valve member.

Preferably, the valve seat and the biasing means are situated on opposing sides of the valve member, the action of the biasing means tending to form an effective sealing arrangement between the valve member and the seat.

As an alternative to performing a shut-off function the safety device may be an automatic opening device such that, in the emergency situation, the operating status changes from a closed configuration, in which the flow path is obstructed, to an open configuration in which fluid is allowed to flow along the flow path. In the closed configuration the fixed member and the closure member may be held together by the linking means and. in the open configuration, are urged apart from each other by the biasing means.

According to a second aspect of the invention, there is provided a fluid control valve comprising :

a valve body de lining a flow path: a valve member movable from a closed position to an open position in which fluid flow can take place along the flow path: and a safety device comprising a closure member and fusible or corrodible linking means adapted to melt or corrode upon the occurrence of an emergency to cause or allow the closure member to move, to cut off fluid flow through the valve.

There may be a valve seat within the flow path, the valve member abutting the valve seat.

Fluid flow may take place through a passage in the valve member.

The safety device may be housed within the valve body, there being biasing means bearing against the closure member to move the closure member when melting or corrosion takes place.

Preferably, the valve seat comprises a first, rigid, seat portion and a second, resilient, seat portion, the valve member normally engaging the resilient portion.

Preferably, the rigid seat portion is of metal and the resilient seat portion is of a plastics material.

Preferably, the resilient seat portion is made of PTFE.

Preferably, the biasing means exerts a degree of compression sufficient to cut off fluid flow through the valve in an emergency, regardless of which side of the valve is the high pressure side.

The biasing means may either abut directly against the valve member, or via a bearing member. The bearing member mav be made of PTFE. The biasing means may comprise a compression spring or one or more disc springs.

The valve member may comprise a ball member.

By way of example, specific embodiments of the invention will now be described, with reference to the accompanying drawings, in which :-

Figure 1 is a side view in cross section of an embodiment of a valve incorporating a safety device;

Figure 2 is a more detailed side view, in section, of part of the safety device of Figure 1 ; and

Figure 3 is an end view of the valve part of Figure 2.

Figure 4 is a side view in section of a second embodiment of safety device; and

Figures 5 to 7 are respectively side sectional views of third to fifth embodiments of safety devices.

The valve shown in Figures 1 to 3 is intended for use as a gas meter control cock, and must therefore be capable of operating at low pressures, for example of less than 1 bar.

The valve comprises a brass body 1 defining a through passageway having an inlet end 2 and an outlet nd 3. Within the passageway, there is a valve seat indicated generally at 4. This seat comprises a rigid shoulder 5 defined by the brass body 1 and a ring 6 of PTFE.

Abutting the o-ring 6 is a valve member in the form of a ball 7 having a passage 8 therethrough. The ball 7 is urged against the o-ring 6 by a compression spring 9. The compression spring 9 acts between a bearing member 10 of brass, and a closure member 1 1 . The closure member 1 1 is held in position in the passageway by fusible linking means 12.

The fusible linking means 12 abuts the closure member 1 1 and also engages a fixed portion 19. which forms part of the valve body 1 .

The fixed portion 19 is shown in more detail in Figures 2 and 3, it comprises a central region 20. suspended in the passageway by two bridging portions 21 . The central portion has a diameter " A " which is less than the internal diameter of the passageway and allows fluid to flow around it by means of apertures 22.

Closure member I I is a washer having a central hole whose diameter is less than the central diameter "A" oϊ^' the fixed portion 19.

In the position shown, with the passage 8 aligned with the valve passageway through the body 1 . the valve is in its open position, with the ball 7 sealingly abutting the o-ring 6.

The ball 7 can however be turned through 90" so that the passage extends at right angles to the valve passageway, and close the valve, by means of a rectangular cross-section spigot 13 which engages in an appropriately shaped socket in the top of the ball 7.

The spigot 13 forms the lower part of a valve spindle 14.

The valve spindle 14 is rotatable in an upwardly extending bore 15 of the valve body. The spindle is retained in position by a circlip l b and the bore 15 also contains an o-ring 17.

A square section operating head 18 is integral with the spindle 14.

In use. the gas flows from right to left as viewed in the figure, and so the gas pressure is applied to the right hand side of the ball 7.

However, since this pressure is extremely low. it may not be sufficient in itself, to urge the ball 7 into sealing engagement with the o-ring 6. However, ample force is provided by the spring 9. The PTFE bearing member 10 enables the ball 7 to be turned relatively easily between the opened and closed position, in spite of the spring pressure.

Thus, the embodiment shown comprises a valve which seals efficiently even under very iow pressures. Indeed, the valve can be used under vacuum conditions.

The valve will of course operate very effectively at high pressures also.

If there is high pressure on the right hand .side of the valve, then this will assist the spring 9 in urging the ball 7 into sealing engagement with the o-ring The valve can be used as a bi-directional valve. Provided that the strength of the spring 9 is selected accordingly, the spring is capable of providing effective sealing, even if a relatively high pressure is applied to the left hand side of the valve.

The spring 9 has a dual function. In addition to forming the seal by urging the ball 7 against the o-ring 6. it also forms part of a safety device comprising additionally the closure member 1 1 , the fusible linking means 12 and the fixed portion 20.

In the event of a fire or an unacceptably high temperature, the fusible linking means 12 is arranged to melt. Melting of the means 12 allows the closure member 1 1 to move, under the action of the spring 9 towards the fixed portion 20. where the closure member overlays the portion 20 and, since the internal diameter of the aperture of the closure member is less than that of the solid central portion 20 of the plug, fluid flow is cut-off. The strength of the spring 9 is selected to be sufficient to cut-off the flow and maintain the valve in the cut-off state in an emergency condition, for any of a range of anticipated fluid pressures.

It will be appreciated that the connection between the spigot 13 and the ball 7 is such as to permit a degree of movement of the ball 7 longitudinally of the through passageway under the influence of the spring 9 and that, to this extent, the ball 7 can be regarded as free floating.

Alterations may be made to the disclosed embodiment without departing from the principal of the invention. For example, the valve spindle design may be altered, the compression spring 9 might for example be replaced by - lϋ - disc springs, and the spring means may act directly on the ball 7 without the interposition of a bearing member as such. The circlips could be replaced by threaded retainers.

In the embodiment shown, the manufacturing tolerances needed to achieve the required range of assembly conditions need not be stringent, since any excess play is taken up by the spring. Since the sealing force is largely dependent upon the spring, and is therefore reasonably consistent, the effort required to open and close the valve will also be reasonably consistent. The turning effort can therefore be reasonably accurately predicted and the valve can be designed so that the turning effort is reasonably low.

A further advantage is that any wear which takes place between the valve seat and the ball is automatically compensated for by the spring.

Although, the embodiment of figures 1 to 3 shows the safety device formed by the closure member 1 1 , the fusible linking means 12 and the fixed portion 20 as an integral part of a fluid control valve, the safety device may be provided independently of such a valve and disposed within a flow line.

Figures 4 to 7 show alternative embodiments of safety devices for use within a flow line. Features similar to those described in relation to figures 1 to 3 are designated bv like numerals.

In the embodiment shown in figure 4 there is shown a flow line 23 incorporating a safety device. The safety device comprises linking means 12. closure member 24. spring 9. a spring retaining circlip 25 and a fixed portion 26 defining an aperture 27. The portion 26 forms an integral part of the flow line 23.

In an emergency situation, the linking means 12 is arranged to melt. The spring 9 is then able to urge the closure member 24 into overlying engagement with the fixed portion 26 to thereby block fluid flow through aperture 27. The circlip 25 acts as a scat for the spring 9 to locate it within the flow line 23.

Referring now to figure 5. a further embodiment of safety device is shown. The device incorporates a closure member in the form of a closure valve which comprises a head 28. a connecting rod 29 and a valve guide 30. The closure valve is situated within the flow line 23 (which may be identical to the flow line 23 of figure 4) with the head 28 on one side of aperture 27 and the guide 30 on the other. The connecting rod 29. linking head 28 to guide 30. is encircled by spring 9. Fusible linking means 12 is provided between valve guide 30 and a retaining circlip 25.

In an emergency, the device of figure 5 works as follows: the fusible linking means melts: valve guide 30 is then free to move, under action of spring 9. into abutment against the portion 26, closing off the aperture 27.

Figure 6 shows a further safety device again incorporating a type of closure valve having a head 28 and connecting rod 29. However, in this embodiment a fixed guide and support 3 1 is provided within the flow line parallel to, and spaced apart from the portion 26. The connecting rod 29, in a normal non-emergency situation, extends through the fixed guide and support 3 1 . The spring 9 encircles the connecting rod and bears against the fixed guide and support 1 and the head 28. On the side of the guide and support 31 opposite to that of the head 28. fusible link means 12 and fixing nut 32 hold the closure \ alve in position.

In an emergency, the fusible link means 12 melts and the head 28 - under action of the spring 9 and guided by guide and support 31 - is brought in.o abutment with the portion 26. closing off the aperture 27.

It should be noted that it is envisaged that the need for fixing nut 32 may be dispensed with and the valve held in place in the open configuration by link means 12 alone.

Figure 7 shows a yet further embodiment of safety device. In this example, the closure member has both a head 33 and a base 34, one on either side of aperture 27 and linked by connecting rod 29. Both head and base extend across the full width of the flow line and act as guides. Spring 9 encircles the connecting rod 29 and bears against the base 34 and portion 26. Link means 12 hold the head 33 away from the aperture 27.

In an emergency, link 12 melts and the device changes to the closed configuration.

In other variations of safety devices and valves the closure member may be pushed or pulled into engagement by biasing means other than springs, such as by pressurised cylinder, gravity or internal line pressure. The safety device may be used in combination with types of valves other than ball valves, for instance butterfly, globe, gate or plug valves or in combination with any other pipeline component.

As an alternative to automatic cut-off in the event of fire, the fusible linking means may be adapted to be easily corrodible such that ingress of chemicals or similar, into a flow line will cause dissolution of the ϋnj ing means and cut-off the fluid flow. The linking means may be adapted to disintegrate or fracture when subjected to shock or excessive pressure.

The safety device could, by rearrangement of the various apertures and components, also be used to initiate a fluid flow instead of cutting it off. For instance, excessive heat could cause a linking means in a sprinkler system to melt and initiate a sprinkling operation.

The reader^'s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. Each feature d isclosed i n this speci fication ( including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one. or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A safety device comprising :

a body defining a flow path: a closure member situated within the flow path; biasing means bearing against the closure member: and fusible or corrodible linking means wherein, in an emergency situation, the linking means melt or corrode, causing the closure member to change an operating status of the device.

2. A safety device as claimed in Claim 1 . in which the operating status changes from an open configuration, in which fluid is allowed to flow along the flow path. to a closed configuration in which the flow path is obstructed.

3. A safety device as claimed in Claim 1 or Claim 2. in which the valve body comprises an internal passageway, forming the flow path, and a fixed member situated within the passageway, the fixed member having a solid portion and one or more apertures, to permit fluid flow through the one or more apertures when in the open configuration, the closure member being of a complimentary construction to that of the fixed member, such that in the closed configuration, the fixed member and the closure member co-operate to obstruct the flow path.

4. A safety device as claimed in Claim 3. in which both the fixed member and the closure member are positioned transversely with respect to the fluid flow path.

5. A safety device as claimed in Claim 4. in which fixing means are provided for retaining the biasing means in position within the body.

6. A safety device as claimed in any one of Claims 3 to 5, in which, in the open configuration, the fixed member and the closure member are held apart by the linking means and. in the closed configuration, are urged towards each other by the biasing means.

7. A safety device as claimed in any one of Claims 3 to 6. in which the closure member is a plate-like member having one or more apertures formed therein.

8. A safety device as claimed in any one of Claims 3 to 6, in which the closure member comprises a closure valve.

9. A fluid control \ alve comprising

a valve body defining a flow path: a valve member movable from a closed position to an open position in which fluid flow can take place along the flow path and a safety device comprising a closure member and fusible or corrodible linking means adapted to melt or corrode upon the occurrence of an emergency to cause or allow the closure member to move, to cut off fluid flow through the valve.

10. A fluid control valve as claimed in Claim 9. having a valve seat within the flow path, the valve member abutting the valve seat.

1 1. A fluid control \ alve as claimed in Claim 9 or Claim 10. in which the safety device is housed within the valve body, there being biasing means bearing against the closure member to move the closure member when melting or corrosion takes place.

12. A fluid control valve as claimed in any one of Claims 9 to 1 1. in which the valve seat comprises a first, rigid, seal portion and a second, resilient, seat portion, the valve member normally engaging the resilient portion.

13. A fluid control valve as claimed in Claim 12. in which the rigid seat portion is of metal and the resilient seat portion is of a plastics material.

14. A fluid control valve as claimed in Claim 13. in which the resilient seal portion is made of PTFE.

15. A fluid control valve as claimed in any one of Claims 1 1 to 14, in which the biasing means exerts a degree of compression sufficient to cut off fluid flow through the \ alve in an emergency, regardless of which side of the valve is the high pressure side.

16. A fluid control \ alve as claimed in any one of Claims 1 1 to 15, in which the biasing means abuts directlv against the valve member.

17. A fluid control \ alve as claimed in any one of Claims 1 1 to 15. in which the biasing means abuts against the valve member via a bearing member. - I S -

18. A fluid control \ alve as claimed in Claim 17. in which the bearing member is made of PTFE.

19. A fluid control valve as claimed in any one of Claims 1 1 to 18, in which the biasing means comprises a compression spring or one or more disc springs.

i

20. A fluid control valve as claimed in any one of Claims 9 to 19. in which the valve member comprises a ball member. -

21. A safety device constructed and arranged substantially as herein described, with reference to Figures 1 to 4. or Figure 5. or Figure 6, or Figure 7 of the accompanying drawings.

22. A fluid control valve constructed and arranged substantially as herein described, with reference to Figures 1 to 4. or Figure 5. or Figure 6, or Figure 7 of the accompanying drawings.