VALVE FOR VESSEL CONTAINING A PRESSURIZED GAS, IN PARTICULAR LIQUEFIED PETROLEUM GAS, A CONICAL PRE-SEALING RING FOR SAID VESSEL, AND A CYLINDER COMPRISING SUCH A VALVE

Abstract: The conical pre-sealing ring (30) is intended to provide temporary sealing while the appliance (20) is being screw­ ed into or unscrewed from the valve (10) of a gas cylinder. Deep penetration of the push-element (21) of the appli­ ance (20) can cause the conical pre-sealing ring (30) to re­ verse and remain in this position, even after unscrewing. According to the invention, to overcome this drawback, the conical pre-sealing ring (30) is provided with radial pro­ tuberances (33) which prevent gas-tight contact between the reversed surface of the conical pre-sealing ring (30) and the valve shoulder (16). This ensures that the space (40) always remains in communication with the gas pressure, so that, on dismantling, the sealing ring is returned to its initial position by a purely pneumatic effect.

Description: VALVE FOR VESSEL CONTAINING A PRESSURIZED GAS, IN PARTICULAR LIQUEFIED PETROLEUM GAS, A CONICAL PRE-SEPI.ING RING FOR SAID VESSEL, AND A CYLINDER COMPRISING SUCH A VALVE The present invention relates to a valve for a vessel containing a pressurized gas, in particular liquefied petroleum gas, a conical pre-sealing ring for said vessel, and a cylinder comprising such a valve. More exactly, the valve is of a type intended for being coupled in a gas-tight manner to the lower part of an appliance provided with a push-element having a passage for a pressurized gas, the valve comprising within a body a bore with a shoulder for receiving said lower part, a conically-shaped pre-sealing ring having its apex facing the lower part of the appliance and capable of being deformed with reversal by the penetration of said lower part, thereby pressing its inner surface against said shoulder, a seat with sealing ring, a valve element resting elastically against the seat and intended to be moved by the push-element, and means, cooperating with the lower part of the appliance, for coupling said lower part and engaging it in the bore. The appliance/cylinder assembly for which such a valve or sealing ring is intended is illustrated in Fig. 1, which shows a valve 10 of a cylinder for containing pressurized gas and the lower part of an appliance, for example a tap nozzle 20 which can be screwed into the valve 10, the screwing action causing the valve element of this valve to open (Fig. 1 shows the two elements 10 and 20 before coupling). The valve 10 comprises a valve element consisting of a steel ball 11 held by a spring 12 in gas-tight contact with a sealing ring 13 having a square or rectangular diametrical cross-section, resting on a seat 18. In addition, there is a threaded bore 14 into which the tap nozzle 20 can be screwed. The e tap nozzle 20 comprises a push-element 21 with a passage 26 for the pressurized gas, the push-element 21 coming into contact with the ball 11 when the thread 22 is engaged in the mating thread of the threaded bore 14 of the valve 10, and a flat sealing ring 23 which ensures the gas-tightness of the tap/valve connection when screwing the tap nozzle 20 into the bore 14 has been completed. The valve shown in Fig. 1 also comprises a conventional conical pre-sealing ring 30 of the type to which the invention relates. This pre-sealing ring 30, whose conical cross-section has its apex 31 facing the push-element 21 of the tap nozzle 20, can press against push-element 21 so as to achieve a temporary sealing or pre-sealing while the tap nozzle 20 is being screwed or unscrewed, i.e. while the relative position of the valve 10 and the tap nozzle 20 is such that there is no longer gas-tight contact with the sealing ring 13 (ball slightly depressed), nor gas-tight contact with the flat sealing ring 23 (screwing incomplete). The following steps take place during the screwing of the tap nozzle 20 into the valve 10: - bringing the flat face 24 of the tap nozzle 20 in contact with the apex 31 of the conical pre-sealing ring 30; - causing the push-element 21 to act on the ball 11 to open the valve, whereby pressure builds up on the inner surface 32 of the conical pre-sealing ring 30 and presses it against the body 17 of the valve 10 (at the bottom of the groove 15 in which it is located) and against the flat face 24 of the tap nozzle 20, then (as deformation increases) against the cylindrical surface 25 of the push-element 21, thereby ensuring pre-sealing; and - finally, to provide sealing when screwing is complete, ccopressing the flat sealing ring 23 against the top surface 19 of the valve 10. During removal, the preceding steps take place in the reverse order: - freeing of the flat sealing ring 23, the temporary sealing being again provided by the conical pre-sealing ring 30; - allowing the ball 11 to return its initial position and closure of the valve 10; and - causing the flat face 24 of the tap 20 to separate from the apex 31 of the conical pre-sealing ring 30, whereby the gas contained in the enclosed space defined by the ball 11, the conical pre-sealing ring 30 and the flat face 24 of the tap nozzle 20 escapes. It should be pointed out that, according to the above, the sealing of the conical pre-sealing ring 30 results from the gas pressure acting on its inner surface 32. After each new filling, a given cylinder, and therefore a given valve, will be used by a different user, and therefore with a different appliance. The dimension A (Fig. 1), which mainly determines the penetration of the push-element 21 of the tap nozzle 20 into the valve 10, is in principle constant from one appliance to another, but there may be variations due to manufacturing tolerances. It has been observed in particular that tap nozzles 20 having a dimension A larder than the nominal dimension can cause a reversal of the conical pre-sealing ring 30 at the end of the screwing, as shown in Fig. 2. Such a reversal renders the conical pre-sealing ring 30 inoperative during unscrewing, since it cannot return unaided to its original conical state. In fact, if dimension A is too large, the inner surface 32 of the conical pre-sealing ring 30 will be stuck against the edge of the valve shoulder 16. In this case, even the smallest leak at the external edge of the conical pre-sealing ring 30 (for example at the bottom of the groove 15) will cause decompression of the volume 40. On unscrewing the tap nozzle 20 the conical pre-sealing ring 30 will remain in its reversed position, since its inner surface 32 is subjected to the ambient pressure. The conical pre-sealing ring 30 therefore remains pressed against the shoulder 16 by the pressure on its other surface. This can result in a leak during the whole transitory period during which the valve element remains partly open: the push-element 21 is no longer in complete contact with the conical pre-sealing ring 30, and the ball 11 has not yet cane into contact with the sealing ring 13. The conical pre-sealing ring 30 can therefore remain permanently reversed so it is no longer able to provide the temporary seal during a subsequent screwing-in of the tap nozzle 20. In extreme circumstances, in which the previously-mentioned appliances penetrate too deeply into the valve, and with the aim of improving the security of the valves described above, it is an object of the invention to provide a means of preventing the reversal of the conical pre-sealing ring. To this end the valve according to the present invention comprises within a body, a bore with a shoulder for receiving the lower part of an appliance, a conically-shaped pre-sealing ring having its apex facing the lower part of the appliance and capable of being deformed with reversal by the penetration of said lower part, thereby pressing its inner surface against said shoulder, a seat with sealing ring, a valve element resting elastically against the seat and intended to be moved by the push-element, and means, in caribination with the lower part of the appliance, for coupling said lower part and engaging it in the bore, wherein the pre-sealing ring comprises, at its inner surface, at least one radial protuberance adapted to prevent gas-tight contact between the inner, possibly reversed, surface of the sealing ring and the edge of the valve shoulder, and to enable the gas pressure to act permanently on this inner surface when the valve element is depressed by the lower part of the appliance. The invention further relates to a cylinder for holding a pressurized gas, the cylinder comprising a valve according to the invention. The invention moreover relates to a conical pre-sealing ring of the type intended for providing pre-sealing between a valve and a lower part of an appliance able to be coupled in a gas-tight manner to the valve, wherein the sealing ring comprises at least one radial protuberance on one of its surfaces. In addition thereto the invention relates to a conical pre-sealing ring for a valve according to the invention. The pre-sealing ring according to the invention will, solely by the action of the gas pressure, return to its original position when the appliance is removed. It is pointed out that this return to the original position is purely the result of a pneumatic effect, the protuberances having no mechanical stiffening effect on the conical pre-sealing ring. Preferably, the pre-sealing ring comprises a plurality of radial protuberances and these protuberances are arranged in a regular angular distribution. Further characteristics and advantages of the invention will become evident from reading the detailed description below, given with reference to the attached drawings, wherein: Figs. 1 and 2, already referred to, show a valve/appliance provided with a conical pre-sealing ring of the prior art; Fig. 3 is a bottom view of the pre-sealing ring according to the invention, viewed from line III-III of Fig. 4; Fig. 4 is a transversal cross-section along line IV-IV of Fig. 3; and Fig. 5 is homologous with Fig. 2, but for a conical presealing ring according to the invention. Fig. 3 is a bottom view of the pre-sealing ring 30 according to the invention, showing the radial protuberances 33. It has been found by experiment that the presence of eight radial protuberances 33 arranged regularly at 450 ensures the return of the conical pre-sealing ring 30 to its original position, whatever the depth of penetration of the push-element 21, even for very large dimensions A (Fig. 1). A standard conical pre-sealing ring 30 has approximately the following dimensions (see Fig. 4): external diameter d1 = 17 iron; internal diameter d2 = 7.5 rtrn; thickness of the conical part a = 1.1 mm and overall height h = 4 itrn. Given these dimensions, protuberances 33 having a thickness e = 1 mm and a width w = 1.3 rrrn enable the desired effect to be obtained without an appreciable change in the mechanical properties of the conical pre-sealing ring compared with a conical pre-sealing ring of the prior art. The conical pre-sealing ring 30 may be made of an elastomer material such as an NBR (nitrile butadiene rubber), or such as epichlorohydrin or polyurethane. These various materials offer a high chemical resistance to normal liquefied petroleum gas, a low permanent deformation after compression, and a high resistance to ageing under the influence of air or heat. Fig. 5 is homologous with Fig. 2, but for a conical presealing ring 30 according to the invention: it can be clearly seen that the space 40 is always in communication, thanks to the radial protuberances 33, with the gas pressure surrounding the push-element 21 and the valve element. It is this communication which ensures the return of the conical pre-sealing ring 30 to its original position, even after deep penetration of the push-element 21.

Claims: CLAIMS 1. Valve of the type intended for being coupled in a gas-tight manner to the lower part of an appliance provided with a pushelement having a passage for a pressurized gas, the valve comprising within a body, a bore with a shoulder for receiving said lower part, a conically-shaped pre-sealing ring having its apex facing the lower part of the appliance and capable of being deformed with reversal by the penetration of said lower part, thereby pressing its inner surface against said shoulder, a seat with sealing ring, a valve element resting elastically against the seat and intended to be moved by the push-element, and means, in combination with the lower part of the appliance, for coupling said lower part and engaging it in the bore, wherein the pre-sealing ring comprises, at its inner surface, at least one radial protuberance adapted to prevent gas-tight contact between the inner, possibly reversed, surface of the sealing ring and the edge of the valve shoulder, and to enable the gas pressure to act permanently on this inner surface when the valve element is depressed by the lower part of the appliance. 2. Valve according to claim 1, wherein the conical pre-sealing ring comprises a plurality of radial protuberances, these protuberances being arranged in a regular angular distribution. 3. Valve according to claim 1, wherein the conical pre-sealing ring comprises eight radial protuberances arranged regularly at 45O 4. Cylinder for holding a pressurized gas, the cylinder comprising a valve according to one of claims 1 to 3. 5. Conical pre-sealing ring of the type intended for providing pre-sealing between a valve and a lower part of an appliance able to be coupled in a gas-tight manner to the valve, wherein the sealing ring comprises at least one radial protuberance on one of its surfaces. 6. Conical pre-sealing ring according to claim 5, wherein it comprises a plurality of radial protuberances, these protuberances being arranged in a regular angular distribution. 7. Conical pre-sealing ring according to claim 6, wherein it comprises eight radial protuberances arranged regularly at 450. 8. Conical pre-sealing ring for a valve according to one of claims 1 to 3.

Inventors: BEAUDOUIN, JEAN-CLAUDE JOSEPH JULIEN
Applicants: SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.
Application year: 1984
Main classification: F16L29
IPC codes: F17C13, F16L29