A hydraulic machine has a first assembly and a second assembly movable in rotation relative to each other about an axis of rotation. The first assembly and the second assembly define an internal volume and are in contact along an interface. The interface between the first assembly and the second assembly is provided with a sealing element positioned in a housing connected to the internal volume via a first duct, and to the surrounding environment via a second duct. The first duct is provided with a sealing element adapted to isolate the housing from the internal volume, where a secondary cavity is formed in the first assembly or in the second assembly. The secondary cavity is connected to the housing and isolated from the internal volume.

A dry running mechanical seal is able to form a direct contact seal for extended periods at both low and high rotational speeds without undue heating or wear of the seal faces. A rear surface of the stator face and corresponding surface of a mounting plate are both lapped for maximum direct contact transfer of heat. Air from a region surrounding the shaft is circulated through a cooling annulus directly behind the stator face and out through exit ports. In embodiments, enlarged scallops or other features on the rotor seal face enhance air turbulence near the seal faces. In various embodiments a surface supporting a dynamic gasket is polished smooth, thereby reducing gasket drag, minimizing the required pressing force between the seal faces, and reducing frictional heating. In embodiments, the rotor seal face shape is optimized to minimize pressure distortions at high pressure.

A piston and cylinder assembly structured to reduce breakaway friction (stiction) upon movement of the piston within the cylinder. The assembly includes a cylinder housing, a piston having a piston crown with a top face and one or more peripheral grooves, and a sealing ring positioned on the piston in each of the one or more peripheral grooves. The piston crown incorporates one or more passageways extending from a space above the piston to a location within the peripheral groove inside of (behind) the sealing ring. An increase in a volume of fluid in the chamber above the piston directs fluid through the passageways into the peripheral groove, thereby pressing the sealing ring against the cylinder wall. A double acting piston embodiment uses at least two sealing rings positioned within at least two grooves, each with associated fluid flow passageways into the grooves behind the sealing rings.

A rotary seal assembly has a first and second machine element spaced apart forming a sealing gap. The first machine element has a seal-holding structure and the second machine element a sealing surface. A rotary seal is held on the seal-holding structure of the first machine element which has a sealing lip, the front side of which faces the sealing surface and at least partially abuts the sealing surface of the second machine element, pretensioned in a dynamically sealing manner. The sealing lip has pockets on its rear side or on its end face facing the high pressure side. The sealing lip on its rear side, in the case of rearwardly arranged pockets, is tensioned against the sealing surface by an elastically deformable pretensioning ring, and is tensioned in the case of the front side pockets by an elastic resilience inherent in the material of the rotary seal.

There is disclosed a labyrinth seal arrangement for gas turboexpanders and the like which reduces process gas losses. The labyrinth seal includes a plurality of axially spaced seal sets with teeth facing a seal member. A plurality of vent ports in between each seal set permits extraction of gradually lower pressure process gas.

A ring base member of a disc seat ring is fixed to a valve disc using a bolt. The valve disc is formed of a first austenitic stainless steel containing 17.0% by mass to 21.0% by mass of Cr and 8.0% by mass to 13.0% by mass of Ni. The ring base member is formed of a second austenitic stainless steel containing 17.0% by mass to 20.0% by mass of Cr and 8.0% by mass to 15.0% by mass of Ni.

A bearing isolator seal having a shut off O-ring is tolerant of axial rotor-stator misalignment and provides an enhanced static seal while minimizing rotational wear. A tapered section of the stator is overlapped by the shut off O-ring. When the rotor is static there is no axial misalignment, and the shut off O-ring is pressed against the tapered section, forming an enhanced seal. During rotor rotation, increased axial misalignment moves the O-ring away from the tapered section, reducing rotational wear. The stator can extend horizontally beyond the tapered section and below the O-ring, so that if the rotor moves beyond a maximum misalignment, there is a “line on line” fit between the stator and rotor. The bearing isolator seal can include labyrinth technology, and the tapered section can include a contour that allows the shutoff O-ring to drag along the surface of the tapered section with no hang-ups or binding.

A sealing structure enables easy fitting of an endless backup ring and includes: tank main body having filling chamber body with filling chamber and mouthpiece portion formed in cylindrical shape integrally with filling chamber body; valve body having insertion portion inserted in mouthpiece portion; O-ring provided between mouthpiece portion and insertion portion; and first backup ring endless and disposed on one side of O-ring to restrict movement of O-ring, wherein annular housing groove is formed on inner circumferential surface of mouthpiece portion such as to be recessed outward with respect to radial direction in order to house O-ring and first backup ring, wherein mouthpiece portion is provided with first cylindrical portion integral with filling chamber body and second cylindrical portion attachable/detachable along axial direction to/from first cylindrical portion, and wherein housing groove is divided along axial direction to face outward when second cylindrical portion detaches from first cylindrical portion.

The invention is a sealing assembly for equipment with movable shafts—such as coaxial and side port swivels, hydraulic swivels, and rotary control devices—that prevents the loss of a high pressure fluid through the clearance existing between a housing and the shaft. The invention is disclosed in the context of a coaxial swivel that conducts high pressure fluid from a stationary first conduit to a rotating second conduit that has dynamic runout, and may be misaligned relative to the first conduit.

The invention relates to a mechanical seal arrangement comprising: a rotating slide ring (2) having a first slide surface and a stationary slide ring (3) with a second slide surface which between them define a sealing gap 4, wherein the first and second slide surfaces have different hardnesses, wherein the harder slide surface has a diamond coating (20) and the softer slide surface is produced from carbon composite material, and wherein an average initial roughness R.sub.a1 (of the diamond coating 20) is less than an average initial roughness R.sub.a2 of the slide surface made from carbon composite material.