Abstract: An elongated filter disposed over a metering passage of a valve. A rotor is rotatably mounted over the filter and includes a scraping surface positioned along the length of the filter. As water enters the valve, the rotor rotates, causing the scraping surface to scrape off any debris along the length of the filter.

Abstract: A gate valve includes a valve body having a cylindrical passage defining a flow path through the valve, a gate for controlling fluid flow through the valve and a replaceable wear-resistant flow-path liner for in the flow path. The flow-path liner includes a plurality of replaceable wear-resistant inserts, including wear sleeves lining ports of the valve body, valve seats and a gate insert for a flow path bore through the gate. Each replaceable valve seat has a wiper ring for cleaning the gate when it opens and closes. By regularly inspecting and replacing worn-out inserts, the service life of the gate valve can be prolonged and the expense associated with replacing or rebuilding the valve body is avoided.

Abstract: An anti-coking bushing assembly for sealing a pintle shaft of an EGR control valve, comprising a bushing carrier disposed in the valve body and supportive of close-fitting pintle shaft bushing liners formed of a polyimide such as Vespel. The bushing carrier and bushing liners are installed into a carbon shield extending into the exhaust flow space within the valve. Within the carbon shield, between the gas flow space and the bushing carrier, is a ring seal on the pintle shaft and a gas expansion chamber to cool exhaust gas escaping along the pintle shaft, allowing contaminants in the exhaust gas to precipitate in the gas expansion chamber. The carbon shield, ring seal, bushing carrier, and bushing liners are conveniently pre-assembled as an anti-coking bushing assembly for subsequent installation into a valve body during final valve assembly.

Abstract: A gate valve includes a valve body having a cylindrical passage defining a flow path through the valve, a gate for controlling fluid flow through the valve and a replaceable wear-resistant flow-path liner for in the flow path. The flow-path liner includes a plurality of replaceable wear-resistant inserts, including wear sleeves lining ports of the valve body, valve seats and a gate insert for a flow path bore through the gate. Each replaceable valve seat has a wiper ring for cleaning the gate when it opens and closes. By regularly inspecting and replacing worn-out inserts, the service life of the gate valve can be prolonged and the expense associated with replacing or rebuilding the valve body is avoided.

Abstract: A self-cleaning valve assembly is provided, such as for use in a vacuum cleaner such as a particularly advantageous vacuum cleaner system that has at least two filters and self-cleans its filters via back-flushing, without needing to stop normal operation to self-clean. Also, a vacuum cleaner is provided that uses permanent, self-cleaning filters, and does not need disposable filters or filter bags, and advantageously can use inexpensive plastic bags. In another vacuum cleaner system, waste is collected in an ordinary plastic bag without any special preparation or modification of the bag being needed. Further, an inventive self-cleaning X-valve assembly cleans itself and is useable in the vacuum cleaner system.

Abstract: A sliding gate valve for use within a bath of molten aluminum. The sliding gate valve includes a pair of opposed ceramic cleaner plates that sandwich a reciprocable gate body. The cleaner plates include a plurality of longitudinal slots that face the gate body. Dross accumulating on the gate body is scraped from the gate body and into the slots when the gate body is reciprocated.

Abstract: A filter includes top and bottom support frames, and one or more middle support frames, which are arranged in such a manner that a second stepped area recessed by a predetermined depth from the outer circumferential surfaces of the top and bottom support frames is formed by the top and bottom support frames and the middle support frames. A pressure control valve of an electronically controllable power steering apparatus includes: a hollow valve body having a first stepped area with a predetermined depth, the first stepped area being formed on the outer circumferential surface of the valve body, where a supply port is formed; and the above-mentioned filter, the filter being fitted in the first stepped area of the valve body. The filter can minimize change of pressure at the filter area while assuring smooth supply of the hydraulic fluid, and can reduce the number of parts, the number of fabricating steps, and the material costs of such a pressure control valve.

Abstract: The invention relates to an electromagnetic valve, the valve coil of which is actuatable by an electric current for removing deposits at the valve seat and the valve closure member in such a manner that the valve closure member impinges upon the valve seat with a defined impulse force.

Abstract: A conduit cleaning or clearing apparatus and method has a housing assembly connectable to a pipeline. The housing has an inlet and outlet leg joined by a bight portion. A cleaning member is rotatably disposed within the housing and may be rotated from a first unobstructing position to a second cleaning position. In the cleaning position, a plurality of spaced apart blades are able to contact and loosen any build-up in the bight portion. A wiping paddle on the cleaning member urges the loosen build-up out the outlet leg and through the drain line. The paddle cooperates with a locator seat on the housing to retain the cleaning member in an unobstructing position when not cleaning or clearing the bight.

Abstract: An anti-coking valve arrangement having a valve body that defines a passage for the flow of fluid medium. Valve seat and valve member positioned within the valve body and function to control the flow of fluid medium. A first anti-coking device is operably associated with the valve stem. A second anti-coking device is operably associated with the bearing guide member. A third anti-coking device is operably associated with the valve member and the valve seat. A fourth anti-coking device is operably associated with the valve stem and the bearing guide. A fifth anti-coking device is operably associated with the bearing guide. A sixth anti-coking device is operably associated between the valve stem and the bearing guide.

Abstract: An exhaust gas recirculation valve assembly including a bushing and pintle shaft sub-assembly having a pintle shaft supported by a sleeve bushing, the contact area between the shaft and bushing being reduced such that coking deposits that form on the remaining contact area can be broken by the force of the valve actuator, thereby preventing sticking of the valve from coking accumulations. Either the shaft surface or the bushing surface is relieved in a pattern of incuse areas and residual bearing areas. A currently preferred pattern is a helix.

Abstract: A varnishing installation includes a varnish line with an inlet end, an outlet end and an auxiliary device. The auxiliary device is connected through a valve arrangement to the varnishing line and the valve arrangement is scrapeable.

Abstract: A system serves to prevent or remove particle build-up in flowing systems, wherein a fluid flows in a conduit to a valve body. A mechanical shock is periodically generated in the valve body that is of a sufficient magnitude to disturb any particle attachment in the conduit or the valve body. The shock may be generated via direct impact with the valve body or passively using the fluid flowing in the conduit.

Abstract: A system serves to prevent or remove particle build-up in flowing systems, wherein a fluid flows in a conduit to a valve body. A mechanical shock is periodically generated in the valve body that is of a sufficient magnitude to disturb any particle attachment in the conduit or the valve body. The shock may be generated via direct impact with the valve body or passively using the fluid flowing in the conduit.

Abstract: A valve insert for a cylinder valve for connecting an LPG tank to a gas consuming appliance has a body member mounted in the outlet end of the cylinder valve and a valve element slidable in the body member and cooperable therewith to control the flow of gas from the tank to the appliance. A quad sealing ring between the valve body and valve element seals against gas leakage therebetween and provides a lubricant reservoir for lubricating the surfaces thereof, and a wiper ring downstream of the quad sealing ring cleans the surfaces and precludes the ingress of foreign matter to the area of the gas sealing quad ring.

Abstract: A fluid control valve for a pipeline pig includes a main valve and a mechanism for operating the main valve. The main valve comprises a valve body communicated to a fluid pipe, a main valve core movably disposed in the inner chamber of the valve body, and a main valve stem connected to the main valve core. The operating mechanism includes a hydrocylinder, which comprises a piston disposed in the cylinder, and a piston rod connected to the piston. The piston rod is transmissibly connected with the main valve stem so as to drive the main valve core by the main valve stem. A valve device includes a pilot valve, positioned in the pipeline which communicates the fluid pipe with the hydrocylinder, and an operator for controlling the actuation of the pilot valve so as to enable the piston to move reciprocally by the pressure of fluid in the fluid pipe.

Abstract: A unit for discharging loose material from a dispensing device to a user unit comprises a discharge tube leading to the user unit and a valve element connecting the dispensing device to the infeed end of the tube. The valve element comprises a first annular element equipped with a shutter device, consisting of a first shutoff element and a second shutoff element connected to each other by permanent magnets, and a second annular element connected to the infeed end of the tube. When the first and second annular elements are separated by the operation of pistons, a gap is created between the two shutoff elements. A pair of concentric seals positioned between the first and the second annular elements isolate the gap from the outside environment so that a cleaning fluid can be made to flow into it.

Abstract: A system serves to prevent or remove particle build-up in flowing systems, wherein a fluid flows in a conduit to a valve body. A mechanical shock is periodically generated in the valve body that is of a sufficient magnitude to disturb any particle attachment in the conduit or the valve body. The shock may be generated via direct impact with the valve body or passively using the fluid flowing in the conduit.

Abstract: A pressure relief valve has a main valve body, a fluid inlet passageway, a fluid outlet passageway, and a piston contained within the main body. The piston has a piston head, slidingly and sealingly engaged within a pressurized cavity in the main valve body. The piston head's principal face, having a given surface area, is exposed to a pressurized gas in the cavity. A piston stem, connected to the piston head, is in sliding communication with a packoff assembly and has an exposed face whose surface area is smaller than the piston head's principal face. The piston stem's exposed face is in communication with the pressurized gas or fluids to be regulated. In operation, a gas or fluid pressurized to a predetermined value in the pressurized cavity acts against the piston head, forcing one or more ports in the piston stem sidewall to be sealed from the fluid outlet passageway.

Abstract: A valve stem has a thickness of hardfaced material on its outer diameter in the area contacting the stem packing where the seal is formed which prevents corrosion, erosion and/or scratching of the valve stem, thereby preventing formation of leak paths. A valve packing comprises a vertically stacked array comprising alternating metal pressure rings and graphite seals.

Abstract: A container valve (2) comprises a housing (3) within which a fluid inlet (5) communicates with a fluid outlet (7) via a valve seat (9) and a valve chamber (10). A closure member (15) is inserted into the valve chamber (10). A spindle (17) is inserted into a guide hole (14) which communicates with the valve chamber (10). The closure member (15) is connected to a handle (18) through the spindle (17). The handle (18) enables the closure member (15) to operate for opening and closing with respect to the valve seat (9). An annular scraper (21) is attached between the closure member (15) and a peripheral wall of the valve chamber (10). The annular scraper (21) has a lip (21a) whose inner peripheral surface is brought into contact with an outer peripheral surface of the closure member (15). A sealing member (23) is attached between the closure member (15) and the guide hole (14).

Abstract: The present invention is directed to an annular metal-bristled brush for cleaning the pintle shaft of a pintle valve, such as an exhaust gas recirculation valve for an internal combustion engine, to prevent coking and failure of the valve. The brush surrounds the shaft, the tips of the bristles making contact with the shaft with sufficient force to dislodge incipient coke deposits but with insufficient force to inhibit the axial motion of the pintle shaft in actuation. Preferably, the brush is disposed in an annular space in the valve body between the pintle shaft bearing and the gas-metering chamber such that the shaft is brushed in both directions during each actuative cycle of the valve. Preferably, the annular space is slightly larger both axially and radially than the corresponding dimensions of the brush so that the brush is free to float without binding the pintle shaft.

Abstract: The present invention generally provides an apparatus and method for improving the process of purging a liquid delivery system used in integrated circuit manufacturing. The liquid delivery system comprises ultrasonic transducers mounted to various components of a liquid delivery system. The transducers may be mounted on housings, isolation valves, fuel injectors, pump assemblies, fluid lines, and/or liquid flow meters. The ultrasonic transducers launch ultrasonic energy that enhance the removal of processing liquids and particulate material from components of the system. The present invention provides for a purge process where a purge fluid, preferably a liquid solvent, is flowed into the liquid delivery system and ultrasonic energy is launched into the purge fluid to enhance dissolution of residual processing liquids and particulate matter in the liquid delivery system, including from cracks and crevices in valves and other complex mechanical devices before being pumped from the liquid delivery system.

Abstract: A plumbing sink trap having a rotatable actuating knob for rotating a sweeper bar through 360°. The sweeper bar forms a part of the U-shaped path for waste water. Rotation of the sweeper bar removes obstructions in the U-shaped path.

Abstract: A method is provided for cleansing a seal of a device used for sealing an evaporative emission control system of an automotive vehicle. The method starts by determining if a request to close the device has been made. If the request to close the device has been made, the method cycles the device a plurality of times to press and lift the seal off of a seat repeatedly. The method also determines if the seal is closed after the cycling step. If the seal is not closed after the cycling step, the method closes the seal. Preferably, the cycling step includes cycling the device at a pre-selected duty cycle, frequency and cycle count. The duty cycle, frequency, and cycle count correspond to calibration tables prepared for the particular device employed to insure that the seal strikes its seat about three times before sealing.

Abstract: A method and apparatus for desorbing processing liquid from a processing liquid delivery line is provided. Non-thermal energy, such as ultrasonic energy or electromagnetic energy, is applied to a processing liquid delivery line. The non-thermal energy may be applied directly to the processing liquid delivery line, or may be applied indirectly via a conducting medium which distributes the energy along the length of the processing liquid delivery line. When non-thermal energy in the form of electromagnetic energy is employed, the frequency of the electromagnetic energy is adjusted to match the vibrational frequency of the absorbed molecules of processing liquid.

Abstract: A method and apparatus for desorbing processing liquid from a processing liquid delivery line is provided. Non-thermal energy, such as ultrasonic energy or electromagnetic energy, is applied to a processing liquid delivery line. The non-thermal energy may be applied directly to the processing liquid delivery line, or may be applied indirectly via a conducting medium which distributes the energy along the length of the processing liquid delivery line. When non-thermal energy in the form of electromagnetic energy is employed, the frequency of the electromagnetic energy is adjusted to match the vibrational frequency of the absorbed molecules of processing liquid.

Abstract: A device for checking the contents of a container (5) for a supply substance (8) that is not self-leveling. The device includes a stirring blade (2) that is rotatable about an axis of rotation (D) for the delivery of the supply substance (8) to a consumer (21), for example, the suction chamber (2) of a lubricating pump, and for freeing the supply substance (8) of air inclusions, with a mechanism for scraping off the supply substance (8) from the stirring blade (2) and with a measuring unit (22) for measuring the fill level of the supply substance (8) in the container (5). The region of the container bottom (9) has openings (18) for transferring the supply substance (8) in a direction toward the consumer (21) and at least one radial stationary flank (1) is disposed, at least locally, in the region of the container center and is spaced from the container bottom (9) such that the stirring blade (2) can be at least partially rotated under the radial stationary flank.

Abstract: A valve stem has a thickness of hardfaced material on its outer diameter in the area contacting the stem packing where the seal is formed which prevents corrosion, erosion and/or scratching of the valve stem, thereby preventing formation of leak paths. A valve packing comprises a vertically stacked array comprising alternating metal pressure rings and graphite seals.

Abstract: A valve stem has a thickness of hardfaced material on its outer diameter in the area contacting the stem packing where the seal is formed which prevents corrosion, erosion and/or scratching of the valve stem, thereby preventing formation of leak paths. A valve packing comprises a vertically stacked array comprising alternating metal pressure rings and graphite seals.

Abstract: A switch valve 10 is provided with an upper body 14 having a plurality of outlet ports 20A, 20B, and 20C and a lower body housing 16 with inlet port 18. The switch valve includes a ball member 22 which is rotatable within the switch valve body 12 for selective fluid communication between the inlet port 18 and the selected one of the plurality of outlet ports. The ball 22 is rotated by a stem 28, which may be powered by an actuator unit. The upper body 14 includes a substantially dome-shaped seating surface 40 for sealing engagement with the outer surface 38 of the ball. The biasing member 48 biases the ball radially in a direction opposite the ball inlet port 24 to obtain the desired sealing engagement. The biasing member is preferably a Belleville spring 48 having a single wrap design.

Abstract: The toilet discharge system includes a valve with a body (1) and a shutter member (2), and an unblocking apparatus for the shutter member which acts to displace the shutter between the closing position and an auxiliary position and to return it subsequently to the closing position. Advantageously, the shutter member is a rotating element, and its displacement takes place along the direction of its rotation axis; the unblocking apparatus can include a pneumatic system which injects air into two chambers (6, 7) defined between the valve body (1) and the shutter member (2), on two opposite sides of the latter. The method of operation consists in submitting the shutter member of the valve to a cycle which includes a displacement between the closing position and an auxiliary position, and subsequent return to the closing position. The shutter member is thereby prevented from becoming blocked, by avoiding formation of scale of lime and the like, and lubrication and cleanliness of the valve are improved.

Abstract: An improved method of cleaning a throttle valve and an apparatus for facilitating such cleaning. The method of cleaning a throttle valve is provided by applying ultrasonic wave to the throttle valve. The throttle valve is juxtaposed in close proximity to the exhaust gas port of the reaction chamber. A cleaning gas of nitrogen is used to clean the throttle valve. The throttle valve is heated by an imbedded control heater.

Abstract: A safety valve to stop flow in the flow pipe (3), the safety valve including a drilling device (8) with its frame (6) to drill a hole in the flow pipe, a winding device (7) fixed to the frame of the drilling device and a band (4) wound with a winding device. The safety valve includes a sleeve to which sleeve a drilling device (8) and a winding device (7) have been fixed and the sleeve has been equipped with systems to fix it to the outside surface of the pipe (3).

Abstract: The invention is a bi-directional cleanout for pipelines such as sewer pipelines and a bi-directional cleanout with a built in backflow preventer. The backflow preventer is a check valve which allows fluid to flow in one direction, but not in the other direction. The bi-directional cleanout is a device which has a single access point at ground level, is located outside a house typically, and which directs a cleanout tool down one of two tool guide tubes. The guide tubes direct the cleanout tool into one of two tool guides which deflect the cleanout tool and cause it to enter the pipeline to be cleaned in a direction towards one or the other of the ends. The check valve is insertable into the pipe level unit in which the tool guides are located. While the pipeline is being cleaned out with the cleanout tool, the check valve can be removed and reinserted after the cleanout procedure is completed.

Abstract: This invention relates to a method and equipment whereby a pig (11) launched into a gas injection line (5) can be inserted into a hydrocarbon flow line (2) in a position close to the subsea wellhead or manifold (1) without interrupting the flow of hydrocarbons and with minimum interference to the process of gas injection.

Abstract: A fluid product valve in which an elastic member containing a normally closed slit is adapted to be selectively stretched by displacement of an actuating member, such as to stretch open the slit over the outlet end of a product discharge passage and allow fluid product to be dispensed therefrom, release of the actuating member allowing the elastic member, and hence the distorted slit, to return to its original configuration, thereby reclosing the outlet end of the passage.

Abstract: A valve stem sealing device used for preventing oil from entering a combustion chamber through a gap formed between a valve guide and a valve stem is disclosed. The valve stem sealing device comprises an annular oil seal surrounding a valve stem and an annular support member fixed to the top of the valve guide so as to hold the oil seal in its place, wherein the support member has an inwardly opening annular recess and rotatably receives the oil seal in the recess, with a bearing being positioned between said oil seal and the side wall of the support member. In addition, a rubber member is tightly interposed between the support member and the valve guide so as to absorb the vibrations caused by a valve operation. Also, a support cap covers the outside wall of the oil seal so that the outside wall of the support cap is brought into contact with the bearing.

Abstract: A pig delivery and transport system shown schematically in FIG. 1 has a looped line generally indicated at (10) divided into three sections (10A), (10B) and (10C). Line section (10A) is a low pressure non-product line section extending from a product receiving facility (PF) or host to an upstream shut-off valve (20). Line section (10B) is a high pressure product line section extending from downstream shut-off valve (22) to host facility (PF) and receives product from wells (W1) and (W2). Intermediate line section (10C) is a connecting line section between shut-off valves (20) and (22) to connect the non-product line section (10A) to the product line section (10B). A pig inserted at host (PF) is transported along low pressure non-product line section (10A) into connecting line section (10C) while upstream shut-off valve (20) is open and vent valve (28) is open in vent line 26.

Abstract: An outlet opening (14) to a branch line 40 in a pipeline 10 is sealed without interrupting the flow of gas in the pipeline 10 by cutting an access opening 60 in the wall 62 of the pipeline 10 opposite the branch line 40. A seal 100 is inserted through the access opening 60 using a sub-assembly 70, which consists of a flange 74 having a screw-threaded through aperture, an externally screw-threaded tube 82 received in the aperture and a rod 80 carrying a handle 72 at one end and the seal 100 at the other. The seal 100 has a sealing face 102 which is part-cylindrical in shape and is held in the correct orientation by the handle 72 while the tube 82 is screwed home. When work on the branch line 40 has been completed a temporary seal 160 is installed in the joint-flange 16 which is welded to the pipeline 10 allowing removal of the isolation valve 64 which is replaced by a blanking flange fitted to the joint-flange 16.

Abstract: A process is disclosed for switching without leaks a double seat valve comprising radial sealing elements shaped in a slide-shaped closure member (3). In order to ensure leakfree switching, in a first embodiment of the process, radial sealing elements (1, 1*) are guided and remain sealed in a cylindrical valve seat surface (5) while the valve is opened. Sealing elements (2, 2*) provided in a second closure member (4) sealingly engage an end section (E) of the radial sealing elements (1, 1*) and the end section (E) is sealing surrounded by the sealing means (2) when the valve is further opened and when it reaches its open position.

Abstract: A check valve has a pivotal arm for striking a flap against a seal that has a knife edge for cutting occasionally lodged debris. The flap without an integral arm is light to provide minimum resistance to flow of fluid in a normal direction. Greater efficiency permits a spring for biasing an actuating mechanism that is aligned with the pivotal arm to be weaker so that fluid can flow more readily in a normal direction and the spring can be reset easier.

Abstract: A control valve for use in a variable assist power steering system of a vehicle having a valve element disposed within a valve chamber formed in a valve housing. The valve element is connected by a coupling to a proportional solenoid which is mounted upon the valve housing The solenoid includes an axially movable armature which is connected by a coupling to the valve element. The coupling transfers axial movement of the solenoid armature to the valve element. The coupling also is operable to minimize the transfer of transverse movement of the solenoid armature to the valve element.

Abstract: A purge valve has a novel seal element on the head end of a reciprocating valve member that features a frustoconical projection for improved noise attenuation and sealing against a flat annular surface of a valve seat. As the projection comes to closed position against the seat surface, it flexes slightly so that the sealing diameter of its rounded free end contracts, to wipe the seat surface. In one embodiment, the seal element is provided with another projection that absorbs impact upon the valve member coming to maximum open position. In another embodiment, an elastomeric damper element is provided on an end of a pole piece of a solenoid assembly to absorb impact of the valve member as it comes to its maximum open position.

Abstract: A device is provided for the interconnection of two flexible flowlines extending between a subsea production station and a surface facility to allow running of a pig from one line to another. The device is a modular crossover apparatus which includes a control valve connected between two curved pipelines and a pair of substantially Y-shaped connections inserted in the flowlines respectively with ends of the curved pipelines remote from the control valve connected to the connections.

Abstract: The present invention relates to an equipment for the interconnection of two lines to allow running of pigs. Particularly, it is applied to subsea pipelines. This device allows the pigging in installations with restraint accessibility. This equipment allows that pigs launched from the first site into the first line, return via the second line back to the first site. It is of a modular conception, and can be installed at any equipment located at the interconnection point of the two lines, even for existent facilities.

Abstract: A shut-off valve includes a housing defining a flow channel and a bore for receiving a rotary actuator, a valve member, and first and second seal rings. The first seal ring cooperates with the valve member to close and seal the flow channel. The second seal ring cooperates with the valve member to seal the actuator bore. The seal rings are composed of radially extending metal lamellae interposed between soft material lamellae. The soft material lamellae are composed of lubricating material having a non-homogeneous structure which have the capacity to form radial freely extending sliding layers. The metal lamellae have, at least in the region around the inside surface of the seal rings, axial deformations. Such axial deformations provide positive mechanical connection to the adjoining soft material lamellae, restricting the soft material sliding layers to at most one third of the lamellae thickness.

Abstract: A rotary valve has a wiper member formed from an elastomeric material, the wiper member extending circumferentially of the valve seat, and, in an unstressed condition of the wiper member, extending radially inwardly of said valve seat, the wiper member being operatively positioned for it to wipe clean an outer circumferential surface of the valve member as the valve member is moved from an open position to a closed position, the wiper member being supported for limited movement relative to the valve seat, whereby, upon stressing of the wiper member by the valve member, the wiper member can retract into the valve seat.

Abstract: A knife gate valve is provided with peripheral seals which can be removed for cleaning and inspection without having to remove the valve from the duct or other conduit to which the valve is mounted. The longitudinal seals are pressure loaded and seat against the edge rather than the face of the gate. The seals are shielded from the abrasive effects of the material flowing through the valve by peripheral spaced apart beams which project into the valve opening. A series of cutouts in the beams allows the space between the beams to be cleaned of any accumulated material during reciprocation of the gate.

Abstract: A reduced height dust valve is described which is used in a trap which utilizes a pair of said valves to remove dust from, for example, a vacuum line, is described. The valve includes a body having a longitudinal flow path, a valve seat detachably mounted in the upper portion of the body and opposed flapper plates which seat against each other to close the valve or are rotated downwardly by actuator shafts to open the valve. The flapper plates define adjacent edges which seat against each other by a sliding action permitted by movement of one of the two actuator arms.