GB2300696A - Safety shut off valve - Google Patents

Abstract

A flow operated shut off valve 50 is incorporated into the small bore supply hose 60 of a fluid operated tool (70 fig 1) and has a valve closure member 56 normally biased into a valve open position by a spring 58. Pressure difference across the valve above a predetermined level eg when a downstream hose bursts causes a flow past the closure member having sufficient impulse acting on the closure member to overcome the biasing force of the spring and shut the valve by pressing the closure member against a seat 57a. An additional shut off valve (30) can be incorporated into the supply. Valves may be colour coded to indicate the shut off threshold.

Description

Shut-Off Valve This invention relates to a shut-off valve and especially to a shut-off valve, for use in a pressurised fluid systems, adapted to automatically prevent or reduce the passage of fluid therethrough in response to the fluid pressure difference across said valve exceeding a predetermined level, for example, in the event of a downstream burst or disconnection of a downstream fluid operated tool.

Pressurised fluid systems comprising a pressurised fluid source which supplies pressurised fluid to a fluid operated tool via a hose, pipe or similar conduit (henceforth generically referred to as a hose) are well known. One problem associated with such systems is that in the event of inadvertent disconnection of the tool, or of a breach in the hose near the tool, pressurised fluid is forced out of the hose, causing the hose to move rapidly in an uncontrolled and unpredictable way. A solution to this problem has been to provide a shut-off valve in the hose adapted to automatically prevent or reduce the passage of fluid therethrough in response to the fluid pressure difference across said valve exceeding a predetermined level. Such shut-off valves are used in, for example, pneumatic systems in which a source of compressed air is connected to a pneumatic tool by a large bore hose.

However, such shut-off valves are unsuitable for use where a large bore hose connected at one end to a source of pressurised fluid is connected at its other end to a smaller bore hose for use with a pneumatic hand tool with relatively small fluid consumption.

This is because the back pressure created by the length of small bore hose may reduce the pressure difference across the shut-off valve sufficiently to prevent operation of the shut-off valve even in the event of a downstream burst or inadvertent disconnection of the tool. It is not appropriate to increase the sensitivity of the shut-off valve in order to enable it to operate under these conditions because to do so would cause the shut-off valve to operate when not required to do so if the pressurised fluid system were used with a tool with a greater fluid consumption.

According to a first aspect of the present invention there is provided a shut-off valve, for use in a pressurised fluid system to prevent or reduce the flow of fluid therethrough in response to the pressure difference across said valve exceeding a predetermined level, said shut-off valve comprising: a body defining a chamber therein, said chamber having a fluid inlet and a fluid outlet; a valve member, provided within said chamber, which may move between a first position, in which said valve does not substantially inhibit the flow of fluid from the inlet to the outlet, and a second position in which said valve member prevents or substantially reduces the flow of fluid from the inlet to the outlet; and bias means which provides a bias force to the valve member tending to force said valve member towards its first position; wherein the shut-off valve is configured such that respectively greater differences between the pressures at the inlet and outlet of said chamber tend to cause respectively greater forces to be applied to the valve member which tend to force said valve member towards its second pOsition, and such that said predetermined pressure difference across the valve provides a sufficient force to overcome said bias force and force said valve member to its second position.

Preferably, said shut-off valve is configured such that fluid inlet is adapted to be connected to a relatively large bore hose.

Preferably, said shut-off valve is configured such that said fluid outlet is adapted to be connected to a relatively small bore hose.

Preferably, said shut-off valve is adapted to be permanently attached to a small bore hose.

Preferably, said shut-off valve includes an externally visible coloured portion, the colour of said portion being indicative of the predetermined level at which shut-off occurs.

According to a second aspect of the present invention there is provided a hose and connection system for connecting a source of pressurised fluid to a fluid operated tool, said system comprising: a first hose having a first end adapted for connection to the output of a fluid source and having a second end connected to a second hose; a second hose having a first end connected to the first hose and a second end adapted for connection to a fluid operated tool; a second-hose shut-off valve, adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said shut-off valve exceeding a predetermined level; wherein said shut-off valve is located between said first hose and said second hose.

Preferably, said second-hose shut-off valve is permanently attached to said second hose.

Preferably, said second hose shut-off valve is provided in the second-hose part of a coupling which releasably connects said first hose to said second hose.

Preferably, said first hose is of a first, relatively large, bore, and said second hose is of a second, relatively small, bore.

Preferably, there is provided a first-hose shut-off valve located at some point between the fluid source and the second end of the first hose, said first-hose shut-off valve being adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said first-hose shut-off valve exceeding a predetermined level.

Preferably, the predetermined level of pressure difference at which the first-hose shut-off valve operates is greater than the predetermined level of pressure difference at which the second-hose shut-off valve operates.

Preferably, said second-hose shut-off valve is in accordance with the first aspect of the invention.

According to a third aspect of the present invention there is provided a method of providing an automatic shut-off or reduction of fluid flow in a fluid system comprising a source of pressurised fluid, an output from said source in the form of a first hose of a first, relatively large, bore, a second hose of a second, relatively small, bore, connection means for connecting said first hose to said second hose and a fluid operated tool, operable by pressurised fluid passing from said source through said first and second hoses to said tool, said method comprising the steps of:: providing, in said first hose between said fluid source and said connection means, a first shut-off valve, adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said first shut-off valve exceeding a first predetermined level; providing a second shut-off valve, adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said second shut-off valve exceeding a second predetermined level; wherein said second shut-off valve is located downstream of said first shut-off valve and said second predetermined level of pressure difference is lower than said first predetermined level of pressure difference.

Preferably, second shut-off valve is located between said first hose and said second hose.

Preferably, said second shut-off valve is permanently attached to said second hose.

Preferably, said method includes use of a shut-off valve in accordance with the first aspect of the present invention and/or a system in accordance with the second aspect of the present invention.

Embodiments of the present invention will now be described by way of example only, with reference to the accompanying drawings in which: Fig. 1 is a schematic illustrating the use of a method, and of an embodiment of the apparatus, in accordance with the present invention; Fig. 2 is a cross-sectional view of an embodiment of a shut-off valve in accordance with the present invention; Fig. 3a is a cross-sectional view of an element of the embodiment of Fig. 2; Fig. 3b is an end view of the element of Fig. 3a; Fig. 4a is an end view of an element of the embodiment of Fig. 2; Fig. 4b is a cross-section and view of the element shown in Fig. 4a; Fig. 5a is an end view of a further element of the embodiment shown in Fig. 2; Fig. 5b is a vertical cross-sectional view of the element of Fig. 5a.

With reference to the drawings, there will now be described system for effecting shut-off and a shut-off valve for use in a pressurised fluid system comprising a pressurised fluid source 10, having an output in the form of a first relatively large bore ose (comprising a first upstream portion of large bore hose 20, and a second downstream portion of large bore hose 40), a second hose 60 of relatively small bore and a fluid operated tool 70 operable by pressurised fluid passing from the said source 10 through said first and second hoses 20, 40, 60 to said tool 70. As shown in Fig. 1 there is provided a first shut-off valve 30 between the upstream and downstream portions of large bore hose 20, 40, and a second shut-off valve 50.The first shut-off valve 30 is adapted to prevent or reduce the flow of fluid therethrough in response to the difference in pressure across said valve exceeding a first predetermined level. The second shut-off valve 50 which, in the illustrated embodiment, also comprises connection means for connecting the downstream portion of the large bore hose 40 to the small bore hose 60, is adapted to prevent or reduce the flow of fluid therethrough in response to the pressure difference across said second shut-off valve exceeding a second predetermined level.

The second predetermined level (at which the second shut-off valve operates) is smaller than the first predetermined level (at which the first shut-off valve operates) thus allowing the second shut-off valve to operate in the event of inadvertent disconnection of the tool 70 from the small bore hose 60 or in the event of a burst in the small bore hose 60. The second shutoff valve 50 may be permanently attached to the small bore hose 60 so that if the fluid source 10 and large bore hose 20, 40 system should be required for use with a higher fluid capacity tool, disconnection of the small capacity tool 70 and small bore hose 60 from the pressurised fluid source 10 will automatically include removal of the second shut-off valve 50 from the pressurised fluid source 10.

With reference to Figs. 2 to Sb, an embodiment of the second shut-off valve 50 comprises a body comprising a first body portion 51 for connection to a large bore hose 40 and a second body portion 52 for connection to a small bore hose 60, said first and second body portions 51, 52 together defining a generally cylindrical chamber 54, having an inlet 53 defined by the first body portion 51 and an outlet 55 defined by the second body portion 52. The first and second body portions 51, 52 are generally cylindrical. Provided in the chamber 54 is a generally cylindrical seat member 57, having a first axial end at which is provided an inwardly extending annular shoulder 57b which defines a circular aperture which is adjacent to and aligned with the outlet 55.The seat member 57 is also provided with a second axial end located approximately axially centrally in the chamber 54 and which forms an annular seat 57a. Located towards the inlet end of the chamber 54 and able to move axially within the chamber 54, is a valve disc 56 which is provided with a central aperture 59. The valve disc 56 is biased towards the inlet end of the chamber 54 by bias means in the form of a coil spring 58, the first end of which engages the valve disc 56 and the second end of which abuts the annular shoulder 57b of the seat member 57.

In use, pressurised fluid flows through the inlet 53 into the chamber 54, around and through the valve disc 56 and through the outlet 55 to the small bore hose 60.

When the small bore hose 60 is intact and the tool is attached thereto, the pressure difference across the cut-off valve 50 is relatively small and the flow of fluid through the second shut-off valve 50 is permitted. However, should the tool 70 become detached from the small bore hose 60 or should be small bore hose 60 burst or become breached, the pressure difference across the valve 50 will increase substantially. The increased pressure difference across the shut-off valve 50 will exert a force upon the valve disc 56 sufficient to compress the spring 58 and thus move the valve disc 56 in the direction of the fluid flow until it abuts the annular seat 57a, thus effectively shutting off the outlet 55 from the inlet 53 and preventing or reducing the flow of fluid through the shut-off valve 50.The shut-off valve 50 therefore operates automatically in order to shut off or reduce the flow of pressurised fluid in response to pressure across the shut-off valve exceeding a predetermined level. After the valve 50 has shut off the fluid supply, the pressure difference across valve 50 will remain above the predetermined level until the breach of the small bore hose, or inadvertent disconnection of the tool is rectified. Upon such rectification the provision of fluid through the shut-off valve 50 via the aperture 59 in the valve disc 56 will eventually cause the pressure difference across the valve 50 to decrease sufficiently for the valve disc 56 to be forced away from the seat 57a by the spring 58, effectively opening the valve 50, and allowing work to be resumed. The predetermined level may be selected, for example by selecting the stiffness of the coil spring used.Typical bores for a small bore hose for use in a pneumatic system are about 6-13mm.

Although not specifically shown in the drawings, in a preferred embodiment the second shut-off valve 50 is permanently attached to the small bore hose 60 and forms part of a first element of a releasable coupling mechanism for releasably coupling the small bore hose 60 to the large bore hose 40. A second complimentary coupling element is attached to the first hose, allowing convenient coupling and decoupling of the hoses. A number of low consumption fluid powered tools, each with an associated small bore hose, shutoff valve and coupling element may be provided, enabling easy connection of a selected tool to the fluid source whilst ensuring that each tool and associated hose is provided with a shut-off valve with operating parameters well suited to the tool's fluid consumption and the hose bore. Higher consumption tools with associated large bore hoses could also be provided with coupling elements to allow easy coupling to the fluid source via the large bore hose 40, and these might not require associated shut-off valves but could rely upon the first shut-off valve (provided in the first hose 40) to provide shut-off in the case of a hose breach or inadvertent disconnection of the tool.

The described embodiments of the present invention therefore provide a method and apparatus enabling unobtrusive automatic shut-off of fluid supply to a small bore hose for use with a low consumption tool, without adversely affecting the subsequent supply of fluid to a larger bore hose, supplying a larger consumption tool, by the same system.

Modifications and improvements may be incorporated without departing from the scope of the invention.

Claims (19)

1. A shut-off valve, for use in a pressurised fluid system to prevent or reduce the flow of fluid therethrough in response to the pressure difference across said valve exceeding a predetermined level, said shut-off valve comprising: a body defining a chamber therein, said chamber having a fluid inlet and a fluid outlet; a valve member, provided within said chamber, which may move between a first position, in which said valve does not substantially inhibit the flow of fluid from the inlet to the outlet, and a second position in which said valve member prevents or substantially reduces the flow of fluid from the inlet to the outlet; and bias means which provides a bias force to the valve member tending to force said valve member towards its first position; wherein the shut-off valve is configured such that respectively greater differences between the pressures at the inlet and outlet of said chamber tend to cause respectively greater forces to be applied to the valve member which tend to force said valve member towards its second position, and such that said predetermined pressure difference across the valve provides a sufficient force to overcome said bias force and force said valve member to its second position.

2. A shut-off valve as claimed in Claim 1 wherein said shut-off valve is configured such that the fluid inlet is adapted to be connected to a relatively large bore hose.

3. A shut-off valve as claimed in either preceding claim wherein said shut-off valve is configured such that said fluid outlet is adapted to be connected to a relatively small bore hose.

4. A shut-off valve as claimed in any preceding claim wherein said shut-off valve is adapted to be permanently attached to one end of a relatively small bore hose, the other end of which is attached, or adapted to be attached to a fluid powered tool.

5. A shut-off valve as claimed in any preceding claim wherein said shut-off valve includes an externally visible coloured portion, the colour of said portion being indicative of the predetermined level at which shut-off occurs.

6. A hose and connection system for connecting a source of pressurised fluid to a fluid operated tool, said system comprising: a first hose having a first end adapted for connection to the output of a fluid source and having a second end connected to a second hose; a second hose having a first end connected to the first hose and a second end adapted for connection to a fluid operated tool; a second-hose shut-off valve, adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said shut-off valve exceeding a predetermined level; wherein said shut-off valve is located between said first hose and said second hose.

7. A system as claimed in claim 6 wherein said second-hose shut-off valve is permanently attached to said second hose.

8. A system as claimed in Claim 7 wherein said second hose shut-off valve is provided in the second-hose part of a coupling which releasably connects said first hose to said second hose.

9. A system as claimed in any of Claims 6 to 8 wherein said first hose is of a first, relatively large, bore, and said second hose is of a second, relatively small, bore.

10. A system as claimed in any of Claims 6 to 9 wherein there is provided a first-hose shut-off valve located at some point between the fluid source and the second end of the first hose, said first-hose shut-off valve being adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said first-hose shut-off valve exceeding a predetermined level.

11. A system as claimed in Claim 10 wherein the predetermined level of pressure difference at which the first-hose shut-off valve operates is greater than the predetermined level of pressure difference at which the second-hose shut-off valve operates.

12. A system as claimed in any of Claims 6 to 11 wherein said second-hose shut-off valve is of the type defined in any one of Claims 1 to 5.

13. A method of providing an automatic shut-off or reduction of fluid flow in a fluid system comprising a source of pressurised fluid, an output from said source in the form of a first hose of a first, relatively large, bore, a second hose of a second, relatively small, bore, connection means for connecting said first hose to said second hose and a fluid operated tool, operable by pressurised fluid passing from said source through said first and second hoses to said tool, said method comprising the steps of:: providing, in said first hose between said fluid source and said connection means, a first shut-off valve, adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said first shut-off valve exceeding a first predetermined level; providing a second shut-off valve, adapted to prevent or reduce the flow of fluid therethrough in response to the fluid pressure difference across said second shut-off valve exceeding a second predetermined level; wherein said second shut-off valve is located downstream of said first shut-off valve and said second predetermined level of pressure difference is lower than said first predetermined level of pressure difference.

14. A method as claimed in claim 13 wherein said second shut-off valve is located between said first hose and said second hose.

15. A method as claimed in either of Claims 13 or 14 wherein said second shut-off valve is permanently attached to said second hose.

16. A method as claimed in any one of Claims 13 to 15 wherein said method includes use of a shut-off valve as claimed in any of Claims 1 to 5 or a system as claimed in any one of Claims 6 to 12.

17. A shut-off valve as hereinbefore described with reference to or as shown in the accompanying drawings.

18. A hose and connection system as hereinbefore described with reference to or as shown in the accompanying drawings.

19. A method as hereinbefore described with reference to or as illustrated by the accompanying drawings.