GB2123531A

GB2123531A - Valves

Info

Publication number: GB2123531A
Application number: GB08318731A
Authority: GB
Inventors: John Alexander Currie
Original assignee: INDUSTRY SECRETARY OF STAT
Current assignee: INDUSTRY SECRETARY OF STAT
Priority date: 1982-07-13
Filing date: 1983-07-11
Publication date: 1984-02-01
Also published as: GB2123531B; GB8318731D0

Abstract

A valve for controlling the flow of fluid from a reservoir comprises a casing (1) defining a chamber (3) and an inlet (4) adapted to be connected to the reservoir, and an outlet (5). The casing contains first and second sealing members, a first sealing member (8) adapted to form a seal between the chamber and the outlet, and a second sealing member (15) adapted to form a seal between the inlet and the outlet. The first and second sealing members are joined by a deformable sleeve (16). The chamber is adapted to contain pressurised fluid which acts on the second sealing member (15) to maintain the seal. Depressurisation of the chamber permits the second sealing member to move, breaking the seal and allowing flow of fluid from the reservoir through the outlet (5). In a modification, the deformable sleeve alone forms the first sealing member. <IMAGE>

Description

SPECIFICATION Improvements in or relating to valves This invention relates to valves for controlling the flow of fluid and is especially but not exclusively suited for use in fire extinguishers.

The conventional arrangement for a fire extinguisher is to have a reservoir of pressurised fluid suitable for extinguishing flames, and a valve mechanism which may be actuated to release the fluid when desired. In one known extinguisher design, the fluid is prevented from escaping from the reservoir by a diaphragm. To actuate the extinguisher a plunger is depressed which drives the sharp point of a striker member into the diaphragm to rupture it, releasing the fluid. This arrangement suffers from the disadvantage that quick and effective release of the fluid is not guaranteed. The penetrating point may cause only a small hole in the diaphragm thereby providing only a restricted pathway for the flow of fluid.

Additionally any hole made in the diaphragm may be sealed by the striker member as it continues to penetrate the diaphragm. The fluid will therefore be unable to escape from the reservoir and the fire extinguisher will fail to be properly actuated.

Alternatively pieces of diaphragm fractured by the striker may become lodged in the outlet pipe through which the fluid flows thereby restricting or even preventing the flow thereof.

It is an object of the present invention to provide a fast acting valve which overcomes, at least in part, some or all of the disadvantages of the prior art valves described above.

Accordingly there is provided a valve for controlling the flow of fluid from a reservoir comprising a casing defining a chamber, said casing having an inlet attachable to a reservoir of pressurised fluid, and an outlet; the chamber containing a first sealing member adapted to form a seal between the chamber and the outlet, and a second sealing member adapted to form a seal between the inlet and the outlet, the first and second sealing members being axially spaced one from the other with the outlet there between, said first sealing member including a deformable sleeve sealed to the second sealing member; the chamber being adapted to contain pressurised fluid, the arrangement being such that a force resulting from the presence of said pressurised fluid in the chamber can act on the second sealing member to prevent movement thereof in a sense such as to break the seal between inlet and outlet; and means for depressurising the chamber to permit movement of the second sealing member and thus permit flow of fluid from the reservoir.

Preferably the means for depressurising the chamber is constituted by the chamber having an opening closed by a third sealing member, rupturable to permit release of fluid to depressurise the chamber. Thus when the third sealing member is ruptured, the pressurised fluid in the chamber may escape through the opening, thereby depressurising the chamber.

In a convenient arrangement the third sealing member is rupturable in response to a mechanically applied force. It is envisaged that there may be provided a striker pin which may be depressed to pierce or shear the third sealing member. Alternatively the third sealing member is rupturable in response to the actuation of an explosive charge. In yet another alternative arrangement the third sealing member is rupturable in response to the actuation of an electrically controlled solenoid.

Conveniently the second sealing member has a bleed aperture to permit a restricted flow of fluid from the reservoir into the chamber, whereby the chamber is provided with fluid at a pressure greater than that of the surrounding atmosphere.

In this arrangement the reservoir is employed as a source of fluid to pressurise the chamber, thereby obviating the need for an additional source of fluid.

However the bleed aperture must be of a sufficiently small diameter to allow depressurisation of the chamber when required.

Conveniently there is provided resilient biasing means acting on the second sealing member to maintain it in a closed position. The second sealing member will therefore be firmly secured in its closed position and prevented from moving even when the pressures of fluid acting on its opposite faces (i.e. in the reservoir and chamber) is equai. It is only when the chamber is depressurised that the resilient biasing means is overcome by the force of the pressure of fluid in the reservoir and the second sealing member permitted to move.

Alternatively or additionally, the area of the second sealing member exposed to the fluid in the chamber is greater than the area thereof exposed to the fluid in the container. The fluid therefore exerts a net force on the second sealing member so as to urge it into a closed position. The member forms a fluid tight seal until the chamber is depressurised and the pressure of fluid in the reservoir breaks the seal.

The deformable sleeve joining the first and second sealing members allows a degree of movement therebetween such that each may accurately locate in its respective closed position.

The sleeve is preferably in the form of collapsible bellows. In one convenient arrangement the first and second sealing members both engage the casing to form face seals therewith. Accordingly both seals are breakable by movement of the sealing members.

Alternatively the deformable sleeve is sealed to a wall of the chamber. Accordingly, with this arrangement, the first sealing member remains sealed despite movement of the second sealing member.

The invention further resides in a fire extinguisher incorporating a valve as hereinbefore described.

Two embodiments of the invention will now be more closely described, by way of example only, with reference to the accompanying drawings, in which Figure 1 is a sectional view of a valve according to the present invention shown when in a closed condition, Figure 2 is a sectional view of the valve of Figure 1 shown when in an open condition, Figure 3 is a sectional view of an alternative embodiment of valve according to the present invention shown when in a closed condition, and Figure 4 is a sectional view of the valve of Figure 3 shown when in an open condition.

The valve of Figures 1 and 2 comprises a substantially cylindrical valve casing 1 closed at one end by an end plate 2 to define therein a chamber 3. The casing 1 has apertures communicating with the chamber 3 to form an inlet 4 and an outlet 5. The inlet is attachable to a reservoir (not shown) of pressurised fluid which may be charged from a fluid source through a duct 6 in the casing, sealed after charging by a plug 7.

Slidably contained within the chamber 3 is a hollow piston 8 constituting a first sealing member. The piston 8 has a flange 9 which seats on a shoulder 10 on the casing which protrudes into the chamber to form a face seal as shown at 1 The flange 9 and shoulder 10 provide a fluidtight seal between the chamber 3 and the outlet 5.

At its opposite end the piston 8 is shaped to form an annular seat 12 against which pushes a coil spring 13. The spring 1 3 is contained between the piston 8 and the end plate 2 and acts to urge into abutment the flange 9 and shoulder 10 so as to maintain the seal 11. The piston 8 terminates with an integrally formed, hollow foot 14 which depends from the seat 12.

Adjacent the foot 14 is a disc 1 5 constituting a second sealing member. The disc 1 5 and piston 8 are connected one to the other by a bellows portion 1 6 which forms a deformable sleeve permitting limited relative movement therebetween. The disc 1 5 is seated on a further shoulder 1 7 on the casing to form a second face seal at 1 8. The disc 1 5 thereby forms a fluid tight seal between the inlet 4 and outlet 5. At the centre of the disc is a bleed aperture 1 9 through which the inlet communicates with the chamber 3.

The end plate 2 has at its centre an aperture 20 in communication with the chamber 3 and providing an opening to the exterior of the valve via space 21 and channel 22. The aperture 20 is closed by a plug 23 secured in place by a locking nut 24. The plug has a bore 28 extending axially through its centre but prevented from communicating with the space 21 by a cap 25 constituting a third sealing member. The cap 25 is integrally formed with the plug 23 and connected thereto via a grooved weak section 26. The cap is further protected by a protective cover 27.

In use the input aperture 4 of the valve is attached to a reservoir of pressurised fluid, which fluid passes through the bleed aperture 1 9 and into the chamber 3 until the pressure therein equals that of the reservoir. Piston 8 and disc 1 5 are both in their respective closed positions with seals 11 and 18 preventing any flow of fluid to the outlet 5 from the chamber and inlet respectively.

The coil spring 1 3 acts against the piston 8 to maintain the seal 11 firmly closed. The uppermost face of the disc 1 5 presents a larger area to the pressurised fluid than the underside thereof. The fluid therefore exerts a net force on the disc in a downward direction in the sense of Figure 1, urging it against the shoulder 1 7 to keep seal 18 firmly closed. A small amount of relative movement between the piston 8 and the disc 1 5 is permitted by virtue of the bellows portion 1 6.

This ensures that both seals 11 and 18 may firmly abut their respective shoulders 10, 1 7, without the need for the piston and disc to be precisely dimensioned. In this state the fluid is safely maintained within the reservoir until required for use.

To actuate the extinguisher the cap 25 constituting the third sealing member is fractured at its weak section 26. This may conveniently be facilitated by removing the protective cover 27 and manually applying a breaking force e.g. by means of a hammer or plunger. Alternatively a striker rod (not shown) may be inserted into the channel 22 and caused to strike and fracture the cap 25.

Once the cap 25 is fractured a pathway is formed for the chamber 3 to communicate via bore 28, space 21 and channel 22 with the exterior of the valve. Fluid in the chamber 3 rapidly escapes, and may not be so rapidly replaced by fluid from the reservoir as the bleed aperture 1 9 is of a relatively small diameter. Consequently the chamber 3 quickly becomes depressurised.

Without the equalising pressure in the chamber 3, the spring 13 is unable to withstand the pressure of the reservoir on the disc 1 5, and the disc and piston move upwardly to the position shown in Figure 2.

With the disc 1 5 now separated from the shoulder 17, the seal 18 is now broken and fluid is free to escape from the reservoir through the outlet, thus providing a jet of fluid, for example to assist in extinguishing a fire. When the reservoir is exhausted of fluid, the disc and piston return under the action of the spring 1 3 to their closed positions as shown in Figure 1. The protective cap 27 may be removed and the broken cap 25 replaced to once again seal the chamber 3. The plug 7 may be removed and the reservoir recharged with fluid through the duct 6. By this method the fire extinguisher may be refilled and is therefore capable of repeated use.

Figure 3 shows an alternative embodiment of valve according to the present invention which obviates the need for the piston of Figure 1. The casing 1 and plate 2 are substantially similar to the embodiment of Figure 1 and elements common to both embodiments are given like reference numerals. The disc 1 5 and chamber 3 are as before, with a coil spring 13 urging into contact the disc and a shoulder 1 7 to form a seal 18.

However instead of the piston of Figure 1, an extended bellows portion 36 forming a deformable sleeve connects the disc 1 5 directly to the shoulder 10 provided on the casing above the outlet 5. The bellows portion 36 constitutes part of the first sealing member preventing flow of fluid from the chamber 3 to the outlet 5.

The actuation of the extinguisher of Figures 3 and 4 is similar to that of the embodiment previously described. The cap 25 is fractured at its weak section 26 to provide a pathway through which fluid escapes from the chamber 3, rapidly depressurising it. As before the coil spring 1 3 is unable to compensate for the depressurising of the chamber and the disc 1 5 moves upwardly due to the pressure of the reservoir, collapsing the bellows portion 36 to the position shown in Figure 4.

The disc 1 5 is now separated from the shoulder 1 7 and the seal 1 8 is consequently broken allowing fluid to flow from the reservoir through the outlet 5 as before. When the reservoir is exhausted of fluid the disc 1 5 is returned to contact the shoulder 1 7 by the action of the spring 1 3. The reservoir can then be recharged as previously described and the extinguisher reused.

It will be appreciated by those skilled in the art that many alterations may be made to the valve designs described above without departing from the scope of the present invention. Although face seals have been described throughout, it will be appreciated that diametric seals could be effectively employed with a minimum of amendment. Similarly various methods of ~depressurising the chamber will be apparent to those skilled in the art, any of which may be effectively employed.

Claims

1. A valve for controlling the release of fluid from a reservoir comprising a casing defining a chamber, said casing having an inlet attachable to a reservoir of pressurised fluid, and an outlet; the chamber containing a first sealing member adapted to form a seal between the chamber and the outlet, and a second sealing member adapted to form a seal between the inlet and the outlet, the first and second sealing members being spaced one from the other with the outlet therebetween, said first sealing member including a deformable sleeve sealed to the second sealing member; the chamber being adapted to contain pressurised fluid, the arrangement being such that a force resulting from the presence of said pressurised fluid in the chamber can act on the second sealing member to resist movement thereof in a sense such as to break the seal between inlet and outlet; and means for depressurising the chamber to permit movement of the second sealing member and thus permit flow of fluid from the reservoir through the outlet.

2. A valve according to claim 1 wherein the first and second sealing members engage the casing to form face seals therewith.

3. A valve according to claim .2 wherein both seals are breakable by movement of the sealing members.

4. A valve according to claim 3 wherein the first sealing member is in the form of a hollow piston slidably contained within the chamber.

5. A valve according to claim 1 wherein the deformable sleeve is sealed to a wall of the chamber.

6. A valve according to claim 5 wherein the first sealing member remains sealed despite movement of the second sealing member.

7. A valve according to any one of claims 1 to 6 wherein the deformable sleeve is in the form of collapsible bellows.

8. A valve according to any preceding claim wherein the means for depressurising the chamber is constituted by the chamber having an opening closed by a third sealing member, rupturable to permit release of fluid to depressurise the chamber.

9. A valve according to claim 8 wherein the third sealing member is rupturable in response to a mechanically applied force.

10. A valve according to claim 8 wherein the third sealing member is rupturable in response to the actuation of an explosive charge.

11. A valve according to claim 8 wherein the third sealing member is rupturable in response to the actuation of an electrically controlled solenoid.

12. A valve according to any one of claims 1 to 11 wherein there is provided resilient biasing means acting on the second sealing member to urge it towards a closed position.

1 3. A valve according to any preceding claim wherein there is provided a bleed aperture to permit a restricted flow of fluid from the reservoir into the chamber, whereby the chamber is provided with pressurised fluid.

14. A valve according to claim 1 3 wherein the area of the second sealing member exposed to the fluid in the chamber is greater than the area thereof exposed to the fluid in the reservoir.

1 5. A valve substantially as hereinbefore described with reference to Figures 1 and 2 or Figures 3 and 4 of the accompanying drawings.

1 6. A fire extinguisher incorporating a valve according to any preceding claim.