Abstract: The gate valve of the invention may be disposed in a flow path through which a hydrocarbon gas produced by thermal decomposition, or an exhaust gas passes. In the gate valve, ring-like valve body seats 5A, 5B, and ring-like retainers 14 and ring-like spacers 17 which are disposed on the both sides of the valve body seats are fitted into ring-like grooves 20 formed on faces of ring-like seal boxes 7 which oppose a sliding valve disc 2, in such a manner that the valve body seats, retainers and spacers are disabled from moving in a radial direction. Ring-like convex portions 21 formed on the ring-like seal boxes 7 are fitted into ring-like concave portions 22 on a valve body 1, in such a manner that the ring-like convex portions 21 are disabled from moving in a radial direction. Even when the sliding valve disc 2 moves, the ring-like valve body seats 5A, 5B, and the ring-like seal boxes 7 do not move.

Abstract: A ball cock for fluids carrying abrasive materials has its inlet passage terminating with a smaller cross section than the mouth of a ball passage which, in turn, has a smaller cross section than the mouth of the outlet passage aligned therewith. The cross sectional differences exceed manufacturing and assembly tolerances and have been found to minimize wear of the ball cock.

Abstract: A high pressure ball valve is disclosed having dual, independent seat to ball seals, the dual seal arrangement including a primary seal and a secondary seal, each operating independently, in proper sequence, each acting in the same direction, and each being pressure actuated, with provision for relieving excess fluid pressure.

Abstract: A sealing arrangement for a valve or shaft is disclosed which is designed to respond to movements of a rotatable element in a particular manner and to increase sealing pressure with increasing fluid pressure. The seal undergoes a radial compressive type movement as the pressure within a vessel housing increases between opposed sealing sleeves and this causes an increase in the sealing pressure. This predetermined movement of the seal creates a spring bias in the seal, urging the seal to return to the original, less stressed condition. Preferably, the seal is of a composite structure and a particular component of the intermediate wall section creates this spring bias. This structure has improved operating characteristics and accommodates a wider range of resilient materials to be used for the sealing washer.

Abstract: A gate valve [10] is disclosed having a secondary seal, wherein the gate [15] forms a metal to metal seal with the seat [29, 134] and wherein a resilient seal [36a] is moved toward the gate [15] in a closed position to form a secondary fluid-tight seal with the gate [15]. A device [31, 34] for deenergizing the secondary seal is provided in order to prevent wear of the secondary seal upon opening of the gate and also to reduce the gate [15] drag caused by the energized secondary seal. Also disclosed is a pressure relief mechanism [40, 141] for the secondary seal adapted to prevent damage to the seal and a mechanism for evenly applying opposing secondary seals.

Abstract: A top entry floating ball valve (10) and method of assembly including a downstream metal seat (62) mounted within an annular recess about a downstream flow passage (22) and an upstream metal seat (80) urged by a Belleville spring (78) into engagement with ball closure member (24). Ball closure member (24) is urged by Belleville spring (78) into sealing relation with downstream metal seat (62). A smooth planar wall surface (16) is defined by valve chamber (14) about the inlet flow passage (20) and Belleville spring (78) may be easily inserted within the valve chamber (14) along smooth planar wall surface (16) behind upstream metal seat (80). Upstream metal seat (80) has an inner spherical surface (82) conforming to the outer spherical surface (26) of ball closure member (24) and may be easily moved manually along the spherical surface (26) for assembly and disassembly.

Abstract: A fluid control valve, which allows selective change of the flow rate of fluid through the valve in the face of high temperatures and high pressures without undue wear to the integral downstream sealing seat, includes a body, having a passageway which consists of a first section and a second section, and a ball disposed in the second section of the passageway. The ball is rotatable around a central axis and has a first through hole of one diameter and a second through hole having a minimum diameter which is smaller than the first diameter. A sacrificial annular upstream seat is disposed upstream from the ball and has an internal diameter smaller than both the diameter of the first through hole and the diameter of the first section of the passageway through the body.

Abstract: A valve is presented comprising a valve body defining a chamber, a valve stem extending into said chamber, a disk attached to the valve stem, a discrete annular seat movably disposed in the chamber, a resilient ring disposed in the chamber adjacent the annular seat, and a retainer fixed in the chamber on a side of the seat opposite from the ring, wherein the ring exercises a bias on the seat in a direction toward the disk, urging the seat into engagement with the disk. The invention further contemplates a method for making the valve.

Abstract: A packingless gate valve is disclosed which includes a housing having opposed similar housing halves with resilient sleeve units which compressibly engage each other in the valve open condition and engage opposite sides of the gate in the valve closed condition. Each sleeve unit has a plurality of compression holes extending axially and arranged at intervals relative to the circumference of the sleeve. An encircling stiffening ring of harder material is encapsulated in each sleeve so as to be positioned at the inner end of the compression holes. The compression holes may be left empty or, alternatively, may be sealed with plastic plugs, filled with closed cell foam or mechanical springs. The compression holes provide space for the displaced volume of sleeve elastomeric material to flow into during opening and closing of the gate.

Abstract: A multiport selector valve incorporates a polished interface between a respective poppet of each port and a displaceable valve spool. A controlled gap exists between each poppet and its respective port fitting to pressurize a recess in which an O-ring is seated during operation of the valve. This results in the O-ring seal being urged against a confronting surface of the poppet which increases the contact force between optical surfaces of the poppet and the spool, particularly during periods of dynamic flow. The construction of the valve results in a unit of high reliability and useful life with attendant reduction of replacement costs.

Abstract: The valve includes a support piece 18 that bends elastically and that bears via its two edges 19 and 20 against a support ring 6 for elastically supporting a dynamic sealing ring 16 that is made of metal. The invention is applicable to butterfly valves.

Abstract: A top entry, trunnion-type ball valve has identical, but oppositely arranged sealing assemblies on both sides of the ball. These sealing assemblies include a seal carriage that holds and maintains in position an annular body seal, an annular ball seal and a resilient O-ring interposed therebetween. The O-ring is located in a cavity between the body seal and ball seal which is open to fluid in the valve through-passage and therefore subject to high pressure in the line. Pressure in the O-ring cavity forces the ball and body seals apart and causes the O-ring to compress and resiliently urge the ball and body seals into sealing engagement with the ball and body, respectively. Angled surfaces formed on the seals enhance sealing by concentrating contact pressures.

Abstract: A cartridge intended to be inserted into a body chamber of a mixer valve, which comprises a cage, a fixed plate of hard material, a movable plate of hard material operatively displaceable in the cage and contacting the fixed plate, the plates having mutually cooperating conformations for controlling the flow rate delivered by the valve and the mixing ratio between hot and cold water, and an operator for effecting the displacement of the movable plate in order to execute these controls. The cartridge cage comprises an operatively fixed bottom which is provided at the outside with seals intended to operate between the cartridge fixed bottom and the bottom of the valve body chamber as a consequence of the tightening of the cartridge, and is provided at the inside with couplings complementary to couplings operatively solid with the fixed plate of the cartridge.

Abstract: A sealing liner is provided with incorporated reaction ring, including two circular substantially concentric sealing elements, namely: a static sealing element and a dynamic sealing element these two elements being connected together by a sealed membrane. The dynamic sealing element has an annular housing containing a resilient deformable bed against which a reaction ring is held applied.

Abstract: A fluid flow control valve is provided with a seal comprising a thin metallic film backed by a resiliently deformable body. The seal is mounted on a closure part which may be either the valve stem or the valve seat. The thin film and deformable body are deformed so as to conform to the surface the metallic film seals against as the valve is closed. As the valve is opened, the deformable body returns to its initial state thus returning the thin film to its initial state.

Abstract: A seat assembly (28) for a valve member (20) includes a seat carrier (40) defining a pocket to receive a rigid seat ring (42). The outer peripheral surface (56) of the rigid seat ring (42) is spaced radially from the inner peripheral surface (45) of the seat carrier (40) to define a radial clearance therebetween of at least around 0.001 inch per inch of flow passage diameter. The sealing surface (58) of the seat ring (42) extends at 45 degrees to the longitudinal axis of the flow passage and the flexing and expansion of rigid seat ring (42) when the valve member (20) is moved to closed position permit the seat ring (42) to conform to irregularities in the adjacent mating sealing surface.

Abstract: A valve whose housing has valve spool receiving means arranged in it so that the spool is able to move between two switching positions reciprocatingly and is able to connect valve ducts in the housing with each other for the passage of fluid. For this purpose it has window-like transversely extending passages, through which the fluid may flow between two valve ducts. While offering a low resistance to flow the valve design leads to large orifices. Special means are provided for sealing and the control of frictional forces during operation.

Abstract: A sealing assembly for valves incorporates an annular rigid seat member forming a reference face sealing surface and having a circular seal recess receiving a circular sealing member and a circular seal retainer member which project forwardly of said reference surface for sealing engagement with said working surface. The sealing element forms radially inner and outer stepped sealing surfaces which establish sealing engagement with the working surface of the valve element at various pressure conditions. The rigid seat element defines a cylindrical outer spring retainer recess which receives a plurality of compression springs for spring urged movement of the seat assembly toward the working surface of the valve element. A spring retainer and positioner element formed of a thin strip of sheet material defines spaced spring receptacles separated by spacer segments.

Abstract: A sealing sleeve for a gate valve is disclosed which is designed to respond to movements of the gate of the valve in a particular manner. The seal undergoes an axial compressive type movement as the gate is moved between opposed sealing sleeves and this causes a predetermined radially inward buckling of an intermediate wall section of the sealing sleeve. This predetermined buckling creates a spring bias in the sleeve, urging the sleeve to return to the original, less stressed condition. Preferably, the sleeve is of a composite structure and a particular component of the intermediate wall section creates this spring bias. This structure has improved operating characteristics and accommodates a wider range of resilient materials to be used for the sealing sleeve.

Abstract: A ball valve (10) has a one-piece valve body (12) with a small diameter bore (16) and an opposed large diameter bore (18) in fluid communication with a valve chamber (14). An annular flange (40) projects within the large diameter bore (18) and a washer-type square spring (50) is inserted within the central opening (44) defined by the flange (40) and then positioned in centered relation on the shoulder (42) defined by the flange (40) for urging the ball valve member (24) into seated position against an annular seat (22) about small diameter bore (16).

Abstract: A seal and seat for ball valves is a circular, elastomeric open torus which is fitted between the ball element and the housing. The open torus has within it, a substantially "v" shaped spring that is fitted within the "u" shaped opening of the torus. In normal operation, the spring member is slightly compressed between the ball and the housing and the ball can "float" between a pair of substantially similar seals on the input and output sides of the ball valve, respectively.

Abstract: An improved airplane toilet drain valve assembly comprising a rotatable valve mounted within a housing and a moveable sealing member which is arranged in contact with the valve surface when the valve is in a closed position and which during operation of the valve is moved away from the valve surface thereby avoid wear or damage due to friction between the seal and rotating valve. The invention further comprises a scraper member mounted within the valve housing which prevents solid waste materials from coming into contact with the seals.

Abstract: A cantilever leaf spring (1) attached to a fixed frame or movable member of a gas isolator is acted on by a bias spring (2) and an additional similar, but not identical, bias spring (12).

Abstract: Gate valve having a primary seal, actuated by fluid pressure in the flow conduit, for preventing leakage along the gate member on the upstream side of the gate valve and a secondary seal actuated by fluid pressure upon leaking of the primary seal and including a self-actuating relief means to prevent build-up of fluid pressure in the valve body in excess of the pressure in the flow conduit.

Abstract: A ball valve seat for high temperature and/or abrasive fluids includes a disc-like spring portion formed as a part of the seat for maintaining a sealed relationship with the valve body and the ball and thus allowing for expansion and contraction of the valve components.

Abstract: A flexible seating apparatus is disclosed for use in rotary valves comprising a flexible seat ring attached to one of the valve body and valve closure member in a cantilevered fashion and maintained thereagainst by a resilient member, the latter being held captive in a pre-formed channel in the flexible seat ring. Slotted fastener holes spaced radially along the flexible seat and corresponding fasteners permit automatic axial ring adjustment and proper positioning of the flexible seat ring upon assembly and initial closure of the valve's closure member. An alternate embodiment is disclosed in which the flexible seat ring is mounted to the other of the valve body and the valve closure member. The present flexible seating apparatus can be used with rotary ball valves and butterfly valves, for example, and further, is advantageously used to permit droptight metal-to-metal valve seating.

Abstract: A kelly valve includes a ball valve structure (10) having a ball valve member (40) with a central bore (42) therethrough mounted within a valve chamber (38) for rotation between open and closed positions. A fluid pressure equalizing opening or port (60) is provided in the quadrant of the ball valve member (40) exposed to the upstream flow passage (20) in closed position (FIG. 2) and exposed to the valve chamber (38) in open position (FIG. 1) thereby making the ball valve member (40) easy to rotate manually even at high downstream fluid pressures.

Abstract: A valve wherein the housing has a first section with a hemispherical socket in one of its surfaces and a second section which overlies the one surface and confines a rotary hemispherical valving element in the socket. A polygonal extension of the valving element is rotatable in and extends through the second section to facilitate rotation of the valving element by means of a handle between a first position in which each two channels in the valving element communicates with a discrete pair of passages in the first section and at least one second position in which the channels are sealed from the passages. Sealing rings surround the passages adjacent the socket and are biased against the valving element by dished springs.

Abstract: The present invention is directed to an improved valve comprising a valve housing, a fluid path therethrough, a seat disposed about the fluid path, a rotatable, curved wedge disposed in the fluid path, an actuator for rotating the wedge between its closed and opened positions and a fixed member for displacing the wedge longitudinally toward the seat as it is rotated between its opened and closed positions. Preferably, the seat is biased toward the hemi-wedge. The rotatable, curved wedge has a curved sealing surface for cooperation with the seat. The wedge includes a bore through its thinner end forming a part of the fluid flow path when opened while its thicker end blocks the fluid flow path in the closed position. The sides of the wedge are curved, one side providing a convex sealing surface and the other side providing a concave thrust surface.

Abstract: A mixing valve includes a faucet body (1), a control mechanism, a support surface (9a) for a fixed valve plate (18) mounted on this support surface, a seal (16, 17) placed between the fixed plate and the support surface and a movable valve plate (19) connected to the control mechanism and appointed to shift in sliding contact with the fixed plate so as to regulate the flow rate and the mixing proportions. An attachment mechanism (31) connects the fixed plate to the support surface, the seal being compressed between them, by these parts exerting a compressive force. The compression of the seal is therefore made independent of the pressure between the fixed and the movable plates which can then be reduced to render better sliding and working of the valve plates. The attachment mechanism can be fixed or removable, and can work near the center of the fixed plate or along its border or in both positions.

Abstract: A ball valve is provided in which an outer housing (1) can be left in a pipeline during servicing and a sub-assembly can be removed as a unit from the top of the outer housing (1). The sub-assembly comprises an inner housing (8) in which a ball member 17 is journalled for rotation, and annular seal adaptors (13) for interposition between the ball member (17) and diametrically opposite openings (3) in the outer housing (1). The seal adaptors (13) are such that they can be easily withdrawn outwardly from the withdrawn sub-assembly to reveal the ball member 17 and the seal adaptors for inspection without having to remove the ball (17) itself. The seal adaptors (13) are also wedged-shaped so that when the sub-assembly is refitted in the outer housing (1), the seal adaptors (13) automatically come into sealing engagement with the ball member (17) and the outer housing (1).

Abstract: A rotary valve assembly having a housing, a valve member and a seal assembly. The seal assembly has at least one seal subassembly with two resilient sealing elements, each having a substantially linear section and a curved section formed integrally with the linear section. The linear and curved sections of the two sealing elements are disposed adjacent each other. The two resilient sealing elements may have different resiliency characteristics.

Abstract: A rotary diverter valve for use in diverting fluid wherein the fluid port intersections between the valve body and rotary element are all at a flat planar interface to provide a flat, zero clearance, metal to metal contact. Live bolting is provided to adjust the contact pressure through a spherical bearing arrangement as will tolerate axial misalignment due to nonparallel loading to eliminate any need for critical torquing and widen manufacturing tolerances and reduce costs. When utilizing a replaceable transition plate between the rotary element and the valve body, wear on costly components is eliminated, and the valve is easy to maintain and repair.

Abstract: A top entry ball valve (10) has a removable top plate (34) to permit the removal of a ball valve member (80). Valve seat assemblies (98, 100) each include a primary metal seat member (102), a concentric secondary elastomeric seat member (104), and a concentric rigid seat retainer 106. The primary metal seal member (104) has a free end portion (108) of a reduced thickness to engage the ball member (80) closely adjacent the bore (82). The valve ball member (80) is mounted for rotation on a lower trunnion (28) of the valve body (12) and an upper trunnion (40) of the top plate (34). A packing (70) about the stem (48) has a downward force exerted thereagainst by Belleville springs (74, 75) that is greater than the maximum internal pressure of the valve (10).

Abstract: Seat structure of valves comprising a seat ring, at least one fixing member secured to a valve body and a concave provided between the body and the fixing member for setting the seat ring therein. The seat ring is provided with an inclined contact face to close a flow passage with a close contact with an inclined sealing face of a closure member and a deflective mounting plate to be sandwiched between the body and the fixing member so that the seat ring may be retained movably in response to a flow pressure in the concave both from one direction and from opposite direction of the flow passage. At the opposite side of the contact face, friction face is provided to slidably engage on a corresponding face provided at the fixing member or a substitute therefor. Said face is so inclined as to form a wedge with the inclined sealing face of the closure member.

Abstract: A ball valve (10) has a ball valve member (34) mounted for floating movement in a valve chamber (32) between an upstream metal seat (102) and a downstream metal seat (104). Each metal seat (102, 104) fits within a recess (100) and has a body portion (110) of a generally uniform thickness adjacent an opposed shoulder (108) with a lip (114) about its inner circumference for sealing against spherical surface (40) of ball valve member (34) at all times. Body portion (110) acts as a Belleville spring and spaces lip (114) from adjacent shoulder (108) at low fluid pressures. A bearing portion (118) has an arcuate seat (120) spaced from spherical surface (40) at low fluid pressures but contacting spherical surface (40) at high fluid pressures. A flexible connector (118) of a relatively thin uniform thickness extends between bearing portion (118) and body portion (110).

Abstract: In a fire-safe butterfly valve a polymeric seat ring is resiliently biassed by a resilient metal energizer ring to hold the polymeric seat ring engaged with the closed valve disc, and an independent metal sealing ring permanently engages with the closed valve disc.

Abstract: A metal valve seat for a butterfly valve or ball valve and has the form of an apertured disc with a radially outward part (4A) by which it is securable to a valve body and a radially inward dished part (4B) which projects laterally around the disc aperture. The valve seat is characterized in that the disc part (4B) is formed circumferentially with a plurality of web-connected fingers which have a radially inward surface of varying generative radius. The invention also consists in a butterfly valve or a ball valve incorporating one or a pair of such metal valve seats.

Abstract: A seal mechanism for butterfly valve of concentric opening with press contacting seal, which comprises a ring-formed seal metal arranged surrounding the valve body under insertion in a radially displaceable manner in a circumferential groove formed around the circumference of the valve body, said seal metal having a rounded outer peripheral face; a seal metal disposed surrounding the inner wall of the valve casing and formed integrally therewith, with its seat face inclining relative to the conduit direction of the valve casing; and two tubular buffer rings inserted in said groove of the valve body in between the bottom of the groove and the inner circumference of the seat metal, each of said tubular buffer rings being split along its entire looping length on the upper or lower side of the ring so as to leave a C-shaped cross section to thereby provide a resilient support for said seal metal on said groove bottom at the neutral position on the seat face between the thrust force components in the inflow and th

Abstract: An arrangement for providing access to the seal rings of a seatless high pressure valve includes an aperture in the valve body and a demountable sealed closure for the aperture. The sleeve within the valve body for transmitting the gland force to the seal rings is made in segments small enough for removal through the aperture to permit access to the seal rings. The valve seal rings may accordingly be replaced without disassembly of the major valve components including the valve plunger and gland.

Abstract: There is provided a seat assembly adapted to be received in a spool bore of a valve having a fluid controlling member for controlling the flow of fluid through the valve, with the spool bore having a threaded interior portion. The seat assembly includes a first member having, located towards one end thereof, a grooved ring adapted to receive a tool, and a threaded exterior portion which is adapted to threadedly engage the interior threaded portion of the spool bore. The seat assembly further includes a second member adapted to be received in the first member, with the second member having a seat face adapted to contact the fluid controlling member. The first member threadedly moves the second member between a first position where the seat face contacts the fluid controlling member of the valve to a second position where the seat face is remote from the fluid controlling member of the valve.

Abstract: A filtered stop including a seal assembly having a rotary seal member with flow ports and a stationary seal member with corresponding flow ports, the rotary seal member being selectively positionable by indexing means which are operable from outside the stop so that the flow ports of the rotary seal member may be positioned either into or out of alignment with the ports of the stationary seal member to automatically shut off the flow of fluid before removal of the filter can be accomplished.

Abstract: A diverter valve for diverting the flow of hot gases has a valve door pivotable between two outlets, each of which is surrounded by a bellows seal having a sidewall of significant width for continuous with the valve door and defining with the door a seal of large area. The sidewall is flat and uninterrupted, and the bellows can be made in various shapes, including circular, rectangular with rounded corners, and rectangular with mitered corners.

Abstract: A spring for a top entry ball valve includes a generally "u" shaped spring body with an open end. The ball valve includes a valve body with inlet and outlet flow passages communicating with a valve chamber. A ball element is mounted in the valve chamber for rotation between open and closed positions relative to the flow passages. A seal element is mounted adjacent each flow passage with a sealing face in opposed sealing relation to the ball element. A moveable seat assembly is located between the seal element and the valve body for maintaining the seal element in sealing relation to the ball element. The spring is located between the moveable seat assembly and the valve body and is adapted to urge the moveable seat assembly and the seal element toward the ball element.

Abstract: A sink handle for use in a water faucet, which may be operated at a minimum use of manual force is disclosed. The sink handle generally includes a valve spindle contained within a body, with the spindle being rotatable by a fluid flow. The sink handle also includes a seat bearing adjacent to said valve spindle and a cushion upon which said spindle is rotatable. A bonnet, which may be opened and closed, permits a flow of a fluid therethrough by opening a movable closure element. The bonnet is rotatable as a result of the rotation of the valve spindle. In preferred embodiments of the invention, O-rings function as the cushion. Additionally, a seat bearing may be impregnated in polytetraflouroethylene.

Abstract: A rapid response poppet valve includes a valve body 10 with an internal cavity 16 in which a valve seat 100 is located. A poppet 70 is mounted for movement toward and away from the valve seat 100 and the valve seat 100 is resiliently biased toward the poppet 70 by a bellows 114 to resiliently mount the seat 100 and additionally seal the seat 100 to the valve body 10.

Abstract: A shear seal valve includes a valve body defining an interior valve chamber and a slide member axially movable in the valve chamber. Fluid passages, formed in the valve body and the slide, are selectively interconnected in accordance with the relative position of the slide member within the valve chamber, and tubular shear seals, biased tightly against the slide, avoid fluid leakage along the slide. To provide low-friction sliding movement of the slide relative to the slide body, a pair of roller bearings are supported by the valve body so as to engage the slide. By mounting the roller bearings to the valve body rather than to the slide itself, the slide can be made smaller, and greater freedom in the location of the fluid passages within the slide is obtained. To simplify construction and assembly, the roller bearings are mounted in a removable cover plate forming a part of the valve body and defining one wall of the interior valve chamber.

Abstract: Duplex filter apparatus suitable for pressure or suction applications includes dual filter housings and a central valve housing having dual, cylindrical, three-way plug valves. Four glass-filled Teflon sleeve seals, each having an inner cylindrical cut edge conform to the valve periphery and seal the valve openings in either a pressure or suction configuration. A wave spring biases each sleeve seal against the plug valve and further o-ring seals utilize the pressure or suction condition to enhance the effectiveness of the sleeve seals. In the pressure configuration a tubular support is used in conjunction with the sleeve seal with the wave spring acting either directly on the sleeve seal or indirectly through an intermediate metal ring which houses the o-ring seals and which minimizes thermal expansion effects.

Abstract: An improved valve apparatus and a method of operation thereof having a spring retainer member means suitable for accommodating a spring means therein for operably coupling thereabove a pipe coupling body means are disclosed. Inside the pipe coupling body means is a ball headed member means having an aperture passing therethrough for blocking off or allowing passage of medium through the pipe coupling body means. The spring retainer member means is turned in one direction in order to allow unimpeded passage or to control the amount of flow thereof of said medium and can be rapidly and efficiently sprung back to its original position in order to completely block off the passage of said medium through the pipe coupling body means for a rapid and efficient "on-off" control thereof.

Abstract: A profiled seal which is subjected to the influence of gas pressure forces in a pressure chamber associated with a rotary slide valve is provided with an enlargement, facing the slide valve, of its inner cross section in order to prevent an inadmissibly large increase of the contact pressure forces between the profiled seal and the slide valve, with an enlargement.