GB851365A - Improvements in or relating to safety control valves for liquid pipelines - Google Patents

Abstract

851,365. Hygrometric apparatus. SHELL RESEARCH Ltd. June 13, 1958 [July 8, 1957], No. 21556/57. Class 97(3) [Also in Group XXIX] A liquid pipeline section comprises a closed angularly disposed branch slidingly and sealingly mounting a sleeve formed at one end with a valve member biassed towards a valve seat to block liquid flow and housing a filter pack which permits the passage of liquids other than water, a restricted orifice or orifices through the sleeve connecting the inlet to the filter pack upstream of the valve, an outlet from the pack communicating with the downstream side of the valve and an external surface or surfaces on the sleeve subjected to upstream pressure having an area which in relation to the pressure drop through the restricted orifice or orifices allows the valve to open under normal flow conditions, and in which free water on contacting the filter pack causes the pack to swell to increase the pressure within the sleeve and cause subsequent closure of the valve. As shown in Fig. 1, a pipeline section 1 connecting, e.g. a kerosene refuelling tanker to an aircraft, comprises a branch 1a closed by an end cap 10 and slidingly and sealingly mounting a sleeve 13a formed with a valve member 15 and biassed towards a valve seat 6 by a spring 16. The sleeve houses a filter pack 20 comprising annular filter papers mounted between end plates 21, 22 on a fluted rod 25 guided at one end in a cap 13b and formed at its other end with a valve plate 27 cooperable with oppositely facing seats 31, 32 formed respectively on the filter end plate 22 and the end of a channel 30 through the base of the sleeve. Normally on the opening of a stop valve downstream of the section with a lowering of pressure on that side, kerosene flows into the section and its pressure acts on an external shoulder 39 on the sleeve to urge the sleeve against the spring 16 to open the valve. At the same time a subsidiary flow of kerosene passes through a restricted orifice 34 in the sleeve, thence through the filter pack 20 and the channel 30. In the event of the kerosene including free water, the filter pack swells and against the action of springs 23, 24 seats the valve plate 27 on the seat 31 to close the outlet from the pack. Pressure then builds up within the sleeve and together with the spring 16 this pressure overcomes the pressure acting on the shoulder 39 to close the valve. In the absence of a filter pack the valve plate 27 will seat on the seat 32 to prevent flow through the section. In a modified construction, Fig. 2, a restricted orifice 61 cooperates with a needle 60 and together with a duct 55 through the sleeve and ports 54 in the end plate 22 connects the interior of the filter pack with the upstream side of the valve. Kerosene in this case flows through the pack to its outside and thence through ducts 48, 47 in the sleeve and the channel 30. The opposite ends of the channel 30 are controlled by a valve face 67 and a cap 65 on an extension 45 on the fluted rod 25. When the valve is open the subsidiary flow through the sleeve is less restricted, the orifice 61 moving away from the needle 60 and also extra flow can take place via ducts 57 and annular recesses 57a, 53 in the sleeve 13a and end plate 22 respectively so that normally the flow through the pack is substantially proportional to the total flow Any absorption of free water by the pack immediately causes swelling thereof and the closure of the channel 30 by the valve face 67. In another embodiment, Fig. 4, the pack 20 is held between an end plate movable with the sleeve and a fixed but adjustable end plate 21, a blind bore in the end of the fluted rod 25, houses a small plunger 85 loaded by a spring 89 and restriction to flow through the pack causes an unbalancing of pressures acting on the two sides of the plunger to move a valve head 82 attached to the plunger to obturate the channel 30. In another construction, the filter pack is held firmly between the bottom of the sleeve and a fixed end plate 21 so that no axial expansion of the filter pack can take place. Absorption of water increases the resistance of flow through the pack whence the increased pressure within the sleeve moves the valve 15 towards closure. Specifications 780,129 and 805,004 are referred to.