Gas capsule

Abstract: A capsule 1 for storing a propellant fluid, for example, helium under pressure comprises a hollow body 2 which includes a frangible area 4. An anchor member 8 attaches an arm 6 to the frangible area 4 such that when a force is applied to the arm 6, said force together with the helium under pressure will cause the frangible area to rupture outwardly of the hollow body 2 thereby to release the helium.

Description: This invention relates to capsules for containing a volume of fluid at high pressure, that is, between 60 and 80 bar. Sealed capsules are well known in circumstances where the force of the fluid under pressure is employed to dispense a substance such as discharging draught beer from a beer dispenser or expelling soda water from a soda siphon. It can also be used for liquid containers for soft drinks or beer under pressure. US Patent 5335808, considered as closest prior art according to the preamble of claim 1, describes a beverage container for soft drinks, beer and the like which includes a hollow body for storing the beverage and a frangible area. Means is provided for fixedly attaching an arm to the hollow body, the arm extending outwardly from the hollow body so that when a force is applied to the arm, the arm will cause the frangible area to rupture with the subsequent release of the beverage contained within the container. Standard one-way soda chargers for preparing soda coater store carbone dioxide at a pressure of more than 400 bars. It is also known to employ sealed capsules containing helium at high pressures in the order of 30 - 40 bar in medical devices using the energy of the pressurised helium to drive a therapeutic agent through the skin of a patient. In PCT published application WO94/24263 there is described a needle-less syringe, which includes a metal capsule containing helium gas at high pressure which is used to force particles of a therapeutic agent through the skin of a patient in a substantially painless manner. The capsule is detachable from the remainder of the syringe and once used, either a new charge of gas can be placed in the capsule or more favourably the capsule can be discarded and a new capsule charged with gas can be attached to the remainder of the syringe. In the circumstance where the gas capsule is a throw away item it is important that it can be manufactured simply and cheaply. In medical applications helium gas is a favoured fluid since it is very light which makes it suitable for use as a propellant for therapeutic agents in that when it impinges against the skin of a patient it will bounce off into the atmosphere and not pass through the skin of the patient. However, helium because it is light, is difficult to contain since it will leak through the most minuscule fault in a container. When the fluid pressure in the container is high the force required to break open the seal is often too high for normal "finger pressure" which is a particular requirement for medical applications. It is an aim of the present invention to provide a capsule for fluid under high pressure which can be manufactured simply and cheaply and can be opened simply by pressing a lever on the outside of the capsule. It is a further aim to provide a capsule for fluid under pressure for example, helium gas, which is substantially leak-proof. It is a further aim to provide a capsule for fluid under pressure that can be easily opened by pressure from a normal adults finger (2kg). According to the present invention a capsule for storing a fluid comprises a hollow body including a frangible area, wherein the fluid is stored at a pressure of at least 60 bar, means for fixedly attaching an arm to the hollow body, the arm extending outwardly from the hollow body such that a force applied to the arm will cause the frangible area to rupture with the subsequent release of fluid, characterised in that the arm is attached to the frangible area so that when the force is applied to the arm in the direction of the hollow body the force acts together with the fluid pressure in the hollow body to cause the frangible area to rupture outwardly. Preferably, the arm is a cantilever and the load is applied at or adjacent the free end of the arm in a direction towards the hollow body. Preferably, the arm is fixedly attached to the frangible area by means of an anchor member located on the outer surface of the frangible area. Alternatively, the arm can be mounted for pivoted movement on the frangible area and may include a foot part located inside the hollow body having an edge for engaging a portion of the frangible area. Embodiments of the invention will now be described by way of example, reference being made to the Figures of the accompanying diagrammatic drawings in which:- Figure 1 is a partial side view partly in cross-section of a first capsule for storing a fluid under pressure; Figure 2 is a view similar to Figure 1 but illustrating a different arrangement of the arm for opening the capsule; and Figure 3 is a view similar to Figure 1 but illustrating a different embodiment of a sealed capsule for storing a fluid under pressure. Referring first to Figures 1 and 2, a sealed metal capsule 1 comprises a substantially cylindrical hollow body 2 for containing a fluid eg. helium gas, under high pressures in the order of 60 - 80 bar. The hollow body 2 is provided at its upper (as shown) end with a frangible area 4. The frangible area 4 is formed by reducing the wall thickness at the upper end of the hollow body 2 over a portion of said end. An arm 6 is fixedly mounted to the outer surface of the frangible area 4 by means of an anchor member 8. The frangible area 4 is defined at least in part by a weakened portion 3 which acts as a 'hinge' and a further portion 5 even more weakened where fracture commences as will be explained. As shown in both Figures, the arm is mounted in cantilever fashion spaced from and extending outwardly from the upper end of the body 2. In use, when the energy of the fluid contained within the hollow body 2 is to be employed to dispense a substance or force particles of a therapeutic agent through the skin of a patient, then a force 'P' is applied at or adjacent the free end of the arm 6 which will cause the frangible area 4 to fracture initially at the portion 5, the portion 3 acting as a hinge. The fluid under pressure is thereby released from the hollow body 2 of the capsule 1. It should be noted that in the above described embodiments, the energy of the fluid eg. helium gas under pressure assists in the rupturing process in that it provides a force tending to lift the frangible area 4 from the remainder of the upper end of the hollow body 2. It will be appreciated that the capsules described with reference to Figures 1 and 2 are relatively inexpensive to manufacture and furthermore are relatively leak-proof. Referring now to Figure 3, where like reference numerals denote like parts, the cylindrical hollow body 2 is provided at its upper (as shown) end with a frangible area 4. The frangible area 4 is defined at least in part by a first weakened portion 3 and a second portion 5 even more weakened. An arm 6 is mounted for pivotal movement about a pivot point 8 on the frangible area 4 and includes a lower (as shown) foot part 9 extending into the interior of the hollow body 2. The foot part 9 includes an edge 10 substantially aligned with the second portion 5 of the frangible area 4. In use, when the energy of the fluid contained within the hollow body 2 is to be utilised to dispense a substance eg. soda water or force particles of a therapeutic agent through the skin of a patient, then a force 'P' is applied at or adjacent the free end of the arm 6 which will pivot about the pivot point 8 thereby causing the edge 10 of the foot part 9 to engage and rupture the frangible area 4 initially at the second weakened portion 5. The pivotal action of the arm 6 together with the pressure of the fluid eg. helium at between 60 and 80 bar will continue the rupturing process with the frangible area 4 being pivoted around the first weakened portion 3 which acts as a hinge. The fluid will thus be released under pressure from the hollow body 2 of the capsule 1. Although reference has been made to the use of the capsules with a needle-less syringe for medical purposes, there are a number of other applications where the force of the contained fluid can be utilised. For example, in the inflation of balloons bearing fluorescent markings for identification by radar and for the inflation of life jackets and dinghies. The energy of the pressurised fluid could also be utilised in a weapon to act as a propellant for a bullet or other projectile.

Claims: A capsule (1) for storing a fluid comprising a hollow body (2) including a frangible area (4), wherein the fluid is stored at a pressure of at least 60 bar means (8) for fixedly attaching an arm (6) to the hollow body (2) the arm (6) extending outwardly from the hollow body (2) such that a force (P) applied to the arm (6) will cause the frangible area (4) to rupture with the subsequent release of fluid, characterised in that the arm (6) is attached to the frangible area (4) so that when the force (P) is applied to the arm (6) in the direction of the hollow body (2) the force (P) acts together with the fluid pressure within the hollow body (2) to cause the frangible area (4) to rupture outwardly. A capsule as claimed in Claim 1, in which the arm (6) is a cantilever and the force (P) is applied at or adjacent the free end of the arm. A capsule as claimed in Claim 1 or Claim 2, in which the arm (6) is fixedly attached to the frangible area (4) by means of an anchor member (8) located on the outer surface of the frangible area (4). A capsule as claimed in any one of Claims 1 to 4 in which the frangible area (4) is defined at least in part by a first weakened portion (3) and a second portion (5) even more weakened. A capsule is claimed in Claim 4, in which the arm (6) is mounted for pivotal movement on the frangible area and includes a foot part (9) located inside the hollow body (2) having an edge (10) for engaging the second portion (5) of the frangible area.

Inventors: BIRCH DAVID W, SHERVINGTON EVELYN A, BIRCH, DAVID W., SHERVINGTON, EVELYN A.
Applicants: BOC GROUP PLC, THE BOC GROUP PLC
Application year: 1996
Main classification: F17C13
IPC codes: A61M5, F17C13, F17C7