Abstract: A flow transducer with a variable orifice formed between a conical valve member tapering in the downstream direction and a sliding piston located downstream of the valve member. A throat member is fixed within a housing upstream of the valve member. An annular chamber is formed between the walls of the housing and the throat member. Radial holes open from the annular chamber into the bore of the throat member. The radial holes are equally spaced, all of the same diameter, and at the same axial position. An upstream tapping extends into the annular chamber.

Abstract: A high pressure hydraulic fluid-flow transducer 10 has a frusto-conical throat 13 obturated by a valve member 14 which is fixed to a spindle 16 slidingly carried in a bearing 17 which is fixed to the one-piece housing 11. The bearing 17 engages a substantial length of the spindle, to prevent wobbling, closely adjacent the smaller throat end 15. The housing 11 has internal screw-threads 21, 22 at both ends, for connecting the sensor into an hydraulic system. Because the compression spring 18 is upstream of the valve member 14, and acts upon the upstream end 25 of spindle 16, the valve member 14 and throat 13 are both readily accessible through the downstream end of the housing, both for inspection purposes and for machining of the throat before insertion of the valve member and spindle. Reverse fluid flow is possible by virtue of a second spring 29, acting between valve member 14 and spindle 16.

Abstract: A differential pressure gauge 10 utilizes a piston member 18 provided with a series of grooves 19 right around it, so that the piston member 18 itself forms the rack of a rack-and-pinion device (pinion 22) for converting linear displacement of the piston member into rotary displacement of the pinion. For sensitivity and accuracy, the seal between the piston member 18 and the passage 13 is a hard-surface-to-hard-surface engagement between substantial (total) hard surface areas at any one time of the passage 13 and the piston member 18, including regions of the surface area of the piston member 18 intermediate mutually adjacent end ones of the grooves 19. In this way, the gauge is insensitive to the base pressure, there being no soft seals to deform under pressure. A magnetic coupling is used through the wall of the housing, which can thus be made completely pressure-tight.

Abstract: This invention concerns a fluid operated valve with a slidable valve member having formations enabling differential operating forces to be applied thereto and preferably having means to relieve pressure from the leading formation during travel of the member to promote `snap` action and preferably being associated with a pneumatic piston and cylinder motor driving an hydraulic pump in an integrated unit constituting a pneumatic/hydraulic convertor.