GB2085567A - Fluid closure and discharge devices - Google Patents

Abstract

A discharge mechanism primarily for a stored-pressure fire extinguisher, in place of the conventional piercer, has a diaphragm 11 closing the outlet passage 18 of the extinguisher, with the central portion of the diaphragm clamped between a pair of plugs 12 and 13. When an operating lever 28 is squeezed a plunger 26 is forced down onto the plug assembly and displaces that assembly upstream into a wider- diameter part of the outlet passage, in so doing the diaphragm 11 being sheared around its periphery to open up the full bore of passage 18 to flow. The plug assembly 12/13 can be allowed to return by releasing the lever 28, to seat against a shoulder 17 and temporarily interrupt the discharge. <IMAGE>

Description

SPECIFICATION Fluid closure and discharge devices The present invention relates to closure and discharge devices for containers of pressurised fluids.

The invention is particularly concerned with containers in the form of fire extinguishers of the stored-pressure type, i.e. those in which a gaseous fire extinguishing agent is stored under its own pressure, or where a liquid or powder fire extinguishing agent is stored in the same container as, and under the pressure of, a gaseous propellant.The invention may, however, also be applied to fire extinguishers of the type where a separate cartridge of pressurised propellant is provided inside a container of fire extinguishing agent to be released into the main container only when discharge of the fire extinguishing agent is desired (in which case the relevant "container" from the point of view of the invention is the said cartridge rather than the main container), and may be found to be of utility in relation to a wide variety of devices which involve storage and discharge of pressurised fluids.

It is common practice for the outlet passageway of a stored-pressure fire extinguisher to be sealed by a frangible diaphragm which is pierced by a suitable actuating mechanism when it is desired to discharge the contents of the extinguisher. Most mechanisms of this type involve a pointed member which is simply thrust into the diaphragm to form an initial hole of relatively small size therein, the size of the hole being increased somewhat as the material of the diaphragm is ripped aside by the force of the escaping fluid. As will be appreciated, the sizes and shapes of the holes produced in this manner can be quite irregular, leading to unpredictable behaviour in the flow of discharged fluid. There is also the possibility of the punctured portion of the diaphragm re-sealing against the piercing member or otherwise obstructing the outlet passageway.

It is an aim of one aspect of the invention to provide a closure and discharge device for a stored-pressure fire extinguisher or other container of pressurised fluid which depends upon a frangible diaphragm to seal an outlet passageway of the container, in which the seal can be broken in a manner which more reliably ensures the opening up of a free flowpath of predetermined dimensions for the discharged fluid.

Accordingly in this aspect the invention resides in a container for pressurised fluid having a closure and discharge device comprising: a frangible diaphragm mounted by its peripheral portion to seal an outlet passageway of the container, with a radially inner portion of the diaphragm being held between an assembly of plug members disposed within the passageway; and an actuating mechanism operable to displace the assembly of plug members upstream in the sense of said passageway thereby to shear that portion of the diaphragm held between said members from its aforesaid peripheral portion.

A device as defined above can be arranged so that substantially the whole part of the diaphragm which extends across the passageway is sheared (i.e. as opposed to being pierced with a point) and displaced upstream with the plug members into a larger cross-sectioned portion of the passageway, or into the main body of the container, to leave a substantially unrestricted outlet flowpath of accurately determined dimensions for the discharged fluid.

Preferably the undisplaced position of the assembly of plug members is defined by the abutment of that assembly against an upstreamfacing seat around the passageway. In such case the parts can be arranged so that the load exerted on the plug assembly by the pressurised contents of the sealed container is transmitted to the seat without imparting significant bending or shear stress to the diaphragm. Also such an arrangement permits the discharge of fluid from the container to be temporarily checked during use by allowing the plug assembly to return to its seated position under the control of the actuating mechanism.

These and other aspects of the present invention will now be more particularly described by way of example, with reference to the accompanying drawings, in which: Figure 1 is a sectional view of the head portion of a stored-pressure fire extinguisher embodying the invention; and Figure 2 is a similar view of an alternative central assembly for the extinguisher of Figure 1.

Referring to Figure 1, the illustrated fire extinguisher comprises a shell 1 to which is welded a neck ring 2, the ring 2 accommodating a central assembly 3 with an operating head 4 thereabove.

The assembly 3 comprises a tubular member 5 which is screwed into a coaxial socket member 6, the socket member being screwed coaxially into the neck ring 2 and sealed thereagainst by a pair of O-rings 7 and 8. The tubular member 5 carries at its lower end a dip tube 9 through which the fire extinguishing agent, e.g. powder, is ejected when the apparatus is used. Clamped between the upper end of the member 5 and the socket 6 is a tapered washer 10 and the peripheral portion of a frangible metal diaphragm 11 , the portion of the diaphragm 11 radially inwards of the washer 10 being held between two plug members 12 and 13.

The diaphragm is of dished cross-section as shown, and the disc-shaped upper plug member 1 2 has a central protrusion which fits together with the dished portion of the diaphragm into a recess 14 in the head of the lower plug member 13, to keep the parts 11/12/13 mutually centred.

The integrity of this sub-assembly is maintained by a coil spring 1 5 compressed between the head of the plug member 13 and a spider 1 6 fixed in the tubular member 5, the spring pressing the head of the plug member 1 3 upwards against the diaphragm 11 and a plug member 12, and the outer peripheral portion of the plug member 12 bearing against an axially-facing annular seat 1 7 surrounding the bore 1 8 of the socket member 6.

The lower plug member 13 extends downwards from its head portion in the form of guide rod 1 9, the lower end of which is slidably borne by a central boss of the spider 1 6.

The operating head 4 is secured to the neck ring 2 by screws (not shown). It comprises a body 20 which defines a fixed hand grip 21 and interconnecting passages 22 and 23 leading to a union 24 to which a flexible discharge hose 25 is coupled. The body 22 also forms a sliding bearing for a plunger 26 sealed to the body by an O-ring 27, and has an operating lever 28 pivoted to it at 29. The extinguisher is operated by squeezing the lever 28 towards the grip 21 to depress the plunger 26. Normally, however, the lever 28 is locked in its illustrated position to prevent unintentional discharge from the extinguisher, by means of a pin 30 passing through the lever and held at each end in apertures in the flanking walls 31 ofthegrip21.

In the inoperative condition of the extinguisher illustrated its charge is retained by the diaphragm 11 extending across the bore of member 6. Since, however, the diaphragm is backed up by the plug member 12 seating against the member 6 at 17, the diaphragm is not subjected to any substantial bending or shearing stress by the pressure loading on the assembly 11/12/13. The diaphragm need not, therefore, be made with the strength and precision of those diaphragms typically employed to seal prior art fire extinguishers where the diaphragm must by itself withstand the full internal/external pressure difference.

To operate the extinguisher the pin 30 is withdrawn and the lever 28 moved to press the plunger 26 downwards against the upper face of the plug member 12. This action is effective to shear the portion of the diaphragm 11 which is held between the plug members 12 and 13 away from its peripheral portion clamped between the washer 10 and the socket member 6. Shearing of the diaphragm permits the assembly of plug members 12 and 13 together with the detached portion of the diaphragm to be moved downwards by the plunger 26 against the action of the spring 1 5 into the larger diameter bore of the tubular member 5, to leave the bore 1 8 of the socket member 6 substantially unobstructed, the parts being guided in this movement by the rod 19 sliding in the spider 1 6.Discharge of the fire extinguishing agent from shell 1 can now take place through the outlet passageway defined by dip tube 9, tubular member 5, bore 18, passages 22 and 23, union 24 and hose 25. At any time, the discharge can be temporarily checked by releasing the lever and allowing the plug members and plunger to return under the action of the spring 1 5 to the position in which the plug member 1 2 seats against the face 1 7 of the socket member 6.

After use, the apparatus can be recharged by the following operation. The operating head 4 is detached by removing its fixing screws, and the central assembly 3 is then removed by unscrewing the socket member 6 from the neck ring 2, for this purpose the socket member being formed as at 32 for engagement by a suitable tool. With the assembly 3 removed the tubular member 5 can be unscrewed from the socket member 6 (member 5 being formed at 33 for engagement by a wrench), and the plug members 12 and 13 separated so that the remnants of the diaphragm 11 can be removed. The components of assembly 3 are reassembled in reverse sequence, with a fresh diaphragm 11, and a fresh quantity of powder or other fire extinguishing agent is placed into the shell 1 through the open neck before the assembly 3 is replaced.Initially on replacement of the assembly 3 the socket member 6 is screwed into the neck ring 2 only to the extent that the upper 0-ring 7 just comes into sealing contact with the neck ring, the lower 0-ring 8, which is on a smaller diameter portion of the member 6, being out of contact with the neck ring at this time. In this position a plurality of pairs of aligned radial bores 34 provided through the engaged members 5 and 6 can communicate with a side bore 35 in the neck ring, which is normally closed by a plug 36.

With the plug removed, the shell 1 can be pressurised with gaseous propellant, e.g. nitrogen or air, for the fire extinguishing agent, a pressure source being connected to bore 35 and charging taking place through bores 34, member 5 and dip tube 9. With the pressure source still connected, final sealing of the extinguisher is effected by screwing member 6 down fully until the 0-ring 8 seals against the portion 37 of the neck ring 2; the pressure source is then disconnected and the plug 36 and head 4 can be replaced.

Turning now to Figure 2, this shows an alternative form of central assembly 3' for the fire extinguisher of Figure 1. This assembly comprises a tubular member 5, socket member 6, dip tube 9, washer 10, spring 1 5 and spider 1 6 all identical to the elements identified by the same reference characters in the previously-described embodiment. However, in this case there is a flat, centrally apertured frangible sealing diaphragm 38 clamped by its peripheral portion between the washer 10 and socket member 6, while the radially inner portion of the diaphragm is held between two plug members 39 and 40. The subassembly 38/39/40 is secured by a threaded post 41 which extends from the top of a guide rod 42 and passes through central apertures in the lower plug member 40 and diaphragm 38 into a tapped bore in the upper, poppet shaped plug member 39, the member 39 being screwed down onto the post 41 until the lower plug member 40 is pressed against the shoulder 43 at the junction of the post 41 and rod 42.

The functioning of this embodiment is in all essential respects equivalent to that described with reference to Figure 1, the only other structural difference required being the provision of a somewhat shorter plunger 26' in view of the greater axial extent of the upper plug member 39 as compared with the plug member 12.

Claims (1)

1. A container for pressurised fluid having a closure and discharge device comprising: a frangible diaphragm mounted by its peripheral portion to seal an outlet passageway of the container, with a radially inner portion of the diaphragm being held between an assembly of plug members disposed within the passageway; and an actuating mechanism operable to displace the assembly of plug members upstream in the sense of said passageway thereby to shear that portion of the diaphragm held between said members from its aforesaid peripheral portion.

2. A container according to claim 1 wherein, on operation of the actuating mechanism, substantially the whole part of the diaphragm which extends across the passageway is sheared and displaced upstream with the plug members into a fluid flow region of larger cross-section than the portion of said passageway normally sealed by the diaphragm.

3. A container according to claim 1 or claim 2 wherein the undisplaced position of the assembly of plug members is defined by the abutment of that assembly against an upstream-facing seat around the passageway.

4. A container according to claim 3 wherein the actuating mechanism is also operable to allow the plug assembly to return to,its position in abutment with said seat subsequent to shearing of the diaphragm, thereby to temporarily check the discharge of fluid through the passageway.

5. A container according to any preceding claim having an opening which is normally closed by a closure assembly which includes means defining said passageway together with said diaphragm and plug members, such closure assembly being removable to allow the introduction of material to the container through said opening.

6. A container according to claim 5 wherein said opening is defined by a ring member in which the closure assembly is sealingly received, and there is a charging port through the wall of said ring member for the introduction of pressurised gas to the container; when the closure assembly is partially inserted into the ring member said port can communicate with the interior of the container whereby the container can be charged with gas through said port, the said opening being sealed against gas leakage by first sealing means; and when the closure assembly is fully inserted into the ring member said port is isolated from the interior of the container by second sealing means.

7. A container according to claim 6 wherein the communication of said port with the interior of the container in said partially-inserted position is by way of a fluid passage through the closure assembly which opens to said outlet passageway upstream of the diaphragm but which is isolated from said port in the fully-inserted position of the closure assembly.

8. A fire extinguisher comprising a container holding a gaseous fire extinguishing agent stored under its own pressure, or a liquid or power fire extinguishing agent stored together with and under the pressure of a gaseous propellant, the said container being in accordance with any preceding claim.

10. A fire extinguisher substantially as hereinbefore described with reference to Figure 1 or Figure 2 of the accompanying drawings.