Pressure reduction arrangement

Abstract

A combination composed of a conduit for conveying a fluid medium along a linear path under very high pressure and a choke disposed in the conduit, the conduit having an inner wall and the choke being composed of a restrictor having a restrictor opening which is constricted relative to the cross section of the conduit and a movable needle mounted for movement in the direction of the linear path for constricting or closing the restrictor opening. The conduit is made of a material capable of withstanding the high pressures exerted on the inner wall of the conduit by the flowing medium and the choke is made of a very hard and brittle material which is resistant to wear. The choke further includes a central insert member having an outer tubular part fastened to the inner wall of the conduit, an inner part supporting the needle within the conduit so that fluid medium flowing through the conduit flows around the needle, and a member connecting the inner part to the outer part. The needle is supported by the inner part for movement relative to the inner part parallel to the linear path. The choke further includes a hydraulic drive unit supported by the inner part and forming a unit with the needle. The central insert member is configured and fastened to the inner wall of the conduit so as to offer only slight resistance to flow of the fluid medium past the central insert member.