Patent GB-1432347-A (GB)
Title: Pressure vessels
IPC: F17C13/06
Filed: 1972-05-13
Abstract: 1432347 Pressure vessels THOMAS ASHWORTH & CO LTD 11 May 1973 [13 May 1972] 22567/72 Heading B1X [Also in Divisions F2 and G1] A pressure vessel, for example a fire extinguisher or a moisture tester, i.e. a device for use in estimating the moisture content of materials, comprises a body having an opening, a removable closure for the opening, a deformable sealing member between the body and the closure, means for restraining the closure against blowing off the body and for applying pressure to the sealing member thereby to compress the member and provide a seal between the body and the closure and, for ensuring that the sealing member will "blow-out" (i.e. deform either by expansion or by rupture to break the seal between the body and the closure) when subjected to a pressure lower than that pressure at which the vessel would fracture, pressure limitation means comprising opposed surfaces on the body and closure which come into face-to-face abutment when a predetermined compressive force has been applied to the sealing member thereby positively to prevent application of further compressive force to the sealing member. The sealing member, which preferably is annular and may be of circular cross-section, preferably is made of resilient material such as rubber, for example nitrile rubber, or other elastomeric material. A moisture tester (of the general type disclosed in Specification 386767) is illustrated in Figure 1 and comprises a body having a cylindrical lower part (not shown) fitted with a pressure gauge (not shown) and a frusto-conical upper part 10, provided with a circular opening 11 whioh is closable by a cap 12 having an annular lip 13 and an annular protrusion 14 which define a first shoulder 15 and a second shoulder 16 between a cylindrical lower part 17 of the cap and the second protrusion and between the protrusion and the lip, respectively. The neck of the body is provided with a forged aluminium yoke 18 pivoted on opposed stub axles 19 and provided with a set-screw 20 having a hand-grip 21. As illustrated in Figure 2, the protrusion is formed on its underside with three equi-angular spaced recesses 22 and on its periphery with a groove 23 in which is located a rubber O-ring 24. The surfaces which limit the compression of the O-ring are the top annular surface of the body and the lower annular surface of the protrusion of the cap. As illustrated in Figures 4 and 5, the lip of the cap may be provided with an annular skirt 25 surrounding the O-ring and depending below the top annular surface 26 of the body so that, in the event of a blow-out, gas escaping from the vessel between the body and the cap past the O-ring is guided close alongside the outside of the body. When the O-ring is compressed between the body and the cap and is sealed in the groove 27 formed in the periphery of the protrusion of the cap, see Figure 4, the O-ring and the adjacent surfaces of the body and the cap define small annular pockets 28. In order to facilitate escape of gas from the vessel in the event of a blow-out, see Figure 5, the underside of the lip of the cap is formed with an annular recess 29 and the inside wall surface of the skirt is formed with vertical grooves 30, for example in a manner such that the inside wall surface of the skirt has the appearance of a series of fine teeth.