Abstract: An actuator for operating a valve comprises a housing, a cap, a ring and a piston. The housing has a connecting interface for being mounted on the valve. The cap substantially covers a first portion of the housing. Both the cap and the housing define a substantially enclosed space inside the housing. The ring sealably covers a second portion of the housing. The ring is equipped with two ports that are in fluid communication with the enclosed space. The piston is slidably located inside the housing. Advantageously, an actuator assembly may include the actuator as previously described and one bonnet, one of the connecting interfaces of the actuator being connected to the bonnet. The bonnet is adapted to be mounted to a valve body.

Abstract: A cage valve for reduced erosion at the outlet bore. The valve is of the type having flow trim arranged transverse to the inlet bore and aligned with the outlet bore, the flow trim including a stationary tubular cage and an external cylindrical flow collar slidable along the side wall of the cage to cover or uncover one or more pairs of main flow ports in the cage side wall. The external flow collar is located for movement between a fully closed position wherein each of the main flow ports is fully covered by the external flow collar and a fully open position wherein each of the main flow ports remains partially covered by the external flow collar such that fluid flow from the inlet through each of the main flow ports is directed angularly into the external flow collar, away from the outlet bore, to reduce erosion at the outlet bore.

Abstract: A regulating valve has a valve body, with an inlet and an outlet for fluid, which are connected by a connecting opening, and a flow control device for the connecting opening, inserted in a seat formed in the valve body. The flow control device has a piston for controlling flow within the connecting opening which is functionally connected to an electric motor adapted to make it slide within a cylinder along a sliding axis, and a monolithic tubular jacket that surrounds, determining its coaxiality, the rotor of the electric motor and the flow control piston, further providing the cylinder.

Abstract: The invention relates to a closure apparatus for a pressure container (14), which can be filled with compressed gas, of a cold gas generator (11), wherein the pressure container (14) comprises a closed base at one end and a container opening (16) at the other end, on which container opening (16) the closure apparatus (12) can be arranged for forming a cold gas generator (11), having a valve body (48, 71) which, in a rest position, closes an ejection opening (18) which communicates with the surroundings, and which valve body (48, 71) can be transferred into a working position by way of a drive apparatus (31) for opening the ejection opening (18), wherein a device (33) which reduces the closing force to be applied and actuates the at least one valve body (48, 71) between a rest position and a working position is provided between at least one valve seat (51) of the ejection opening (18) and the drive apparatus (31).

Abstract: A pressure compensation member suitable to be placed in a fluid dispensing channel, a valve unit comprising this pressure drop compensation member and a container comprising this pressure compensation member or this valve unit are disclosed. The pressure compensation member is adapted to maintain a substantially constant flow of fluid through the fluid dispensing channel.

Abstract: The present invention relates to an “improved piston valve for diaphragm pump” features that each of water discharge base and water discharge base has a top camber concave surface with orientating hole center and orientating hole center as lowest point respectively; After anchoring anti-backflow plastic gasket into water discharge base, a gap is formed between bottom surface of anti-backflow plastic gasket and top camber concave surface of water discharge base; Likewise, after anchoring each piston slice into each corresponding water inlet port, a gap is formed between bottom surface of piston slice and top camber concave surface of water inlet port; By functions of foregoing gaps, the overall compressing efficiency is substantially enhanced because both sucking forces of anti-backflow plastic gasket and piston slice are further increased by reciprocal actions of piston pusher.

Abstract: A blow molding machine having the valves integrated into the valve block (100) is disclosed. The valve pistons (110) form annular rings stacked vertically along the stretch rod (104) axis. The valve pistons activate by moving up/down along the stretch rod axis. The valve seat for each vertically stacked valve is formed radially around the stretch rod.

Abstract: A valve apparatus for controlling fluid flow between a fluid passage and a fluid delivery conduit therein includes a valve housing having first and second housing ports spaced therealong, and a driven member driveable toward and away from the first housing port. A closure member having a port is coupled to the driven member and slidable therealong. The driven member and closure member close and open the closure member port during movement of the driven member toward and away from the first port to induce and relieve a pressure differential, exerted on the closure member by fluid entering the housing, acting to slide the closure member along the driven member to close the first housing port. An inductive coil extends about an open end of the housing to receive a coil-equipped end of a probe therein to communicate the probe with monitoring and control systems across the valve.

Abstract: A novel valve assembly is provided. In one embodiment, the valve assembly includes a seat plate that includes a fluid conduit and an impact bushing that is coupled to the seat plate at a position adjacent to the fluid conduit. The valve assembly also includes a sealing assembly that is configured to form a seal with the impact bushing and to control flow of a fluid through the fluid conduit via relative displacement of the sealing assembly from the impact bushing. Systems and methods related to such a valve assembly are also disclosed.

Abstract: A valve assembly includes a housing having a valve bore, a valve seat, and at least one port communicating with the bore. A moveable plunger resides in the valve bore and selectively seals against the valve seat. A bobbin integral with the housing has a solenoid bore adjacent to and coaxial with the valve bore. A moveable armature resides in the solenoid bore and has an operating rod connected to the plunger. A pole piece resides in the solenoid bore adjacent the armature. A solenoid coil is wound about the bobbin. A flux conductor partially surrounding the bobbin, pole piece, and armature. An assembly method includes flowing air through the port, inserting the plunger or another sealing element into the bore while monitoring the fluid flow; and stopping the plunger or sealing element when the flow is at a preselected condition.

Abstract: In accordance with the present invention, there is provided a dirty service valve including an axial trim which, as a result of its structural attributes and extended stroke length, provides increased Cv capacity relative to valve plug size in comparison to existing prior art designs. In accordance with one embodiment of the present invention, the axial trim integrated into the valve of the present invention is configured to provide a linear flow characteristic. In accordance with an alternative embodiment of the present invention, the axial trim may be configured to provide a non-linear flow characteristic which, coupled with the extended stroke length thereof, provides improved flow control in addition to increased Cv capacity. The axial trim possessing the above-described structural and functional attributes may also be integrated into an axial body or housing, thus making the use of rotary actuators in conjunction with the axial trim more feasible.

Abstract: Embodiments of valves permit liquids such as water to flow therethrough at a relatively high flow rate when the temperature of the water is below a predetermined level. The valves reduce the flow rate when the temperature of the water is at or above the predetermined level. The valves can thus facilitate purging of cold water from the hot-water supply piping upstream of the valves at a relatively fast rate, while reducing the flow rate of the water once the water reaching the valves has warmed to a comfortable level.

Abstract: A valve assembly (10) to regulate the flow of a refrigerant. The valve assembly (10) includes a movable valve member (25) to which there are attached two pistons (29 and 30). A refrigerant under pressure is applied to the pistons (29 and 30) to cause movement of the movable valve member (25) to connect or disconnect pipes (17 and 18) through which the refrigerant is to flow.

Abstract: A gas valve may include a valve body and a valve member disposed within the valve body. A resilient sealing ring may be disposed within the valve body such that the valve member achieves a closed position when the valve member contacts the resilient sealing ring. In some instances, a gas valve may include both an upper resilient sealing ring and a lower resilient sealing ring. The upper resilient sealing ring and the lower resilient sealing ring may both permit overtravel.

Abstract: Interference fit assembly (10) of a first metal part (12) and a second metal part (18), wherein the first metal part (12) has a recess (14) with an inner contact surface (16), and the second metal part (18) has an outer contact surface (20) being coupled to the inner contact surface (16) by an interference fit. At least one of the contact surfaces (16, 20) has a surface layer (22) has a diamond-like carbon layer (24). In a method for producing an interference fit assembly (10) the surface layer (22) is applied on at least one of the contact surfaces (16, 20) by a Physical Vapor Deposition (PVD) or a Chemical Vapor Deposition (CVD) process with the surface layer (22) having the diamond-like carbon layer (24).

Abstract: In accordance with the present invention, there is provided an axial drag control valve which includes an internal disk stack trim and an internal actuator. The fluid inlet and outlet of the valve are disclosed along a common axis, which is further shared with the actuator of the valve. The actuator moves along this particular axis to control the fluid flow rate, pressure, or temperature of the system. The valve actuator may be powered by air from an external source.

Abstract: A valve for a gas heater includes an on-off valve for determining supply of a working fluid; and a proportional control valve connected to the on-off valve and controlling a flow rate of the working fluid of which supply has been initiated, wherein the proportional control valve is provided with a body having a passage part through which the working fluid passes and a plunger which is movably installed in the body and open and closes the passage part, and the passage part and the plunger are in linear contact with each other.

Abstract: In accordance with the present invention, there is provided an axial drag control valve which includes an internal disk stack trim and an internal actuator. The fluid inlet and outlet of the valve are disclosed along a common axis, which is further shared with both the plug and the actuator. The plug and actuator move along this particular axis to control the fluid flow rate, pressure, or temperature of the system. The valve actuator may be powered by an operating fluid such as air supplied from an external source. A special, two-part packing with a lantern ring and leak-off port provides protection and safety for the actuator.

Abstract: An isolation valve includes a shield that surrounds and protects the valve closure actuator components from exposure to corrosive fluids that flow through the valve when the valve is open.

Abstract: A valve assembly includes a valve body having an inlet port and an outlet port, the valve body also having a valve chamber extending between the inlet port and the outlet port, a pair of seals each being located on opposing ends of the valve chamber; and a reciprocating piston extending into the valve chamber and movable between a closed position extending through the pair of seals and an open position extending only through one of the pair of seals, wherein the inlet port is fluidly connected with the outlet port when the piston is in the open position. A method of using the valve assembly is also disclosed.

Abstract: A re-closable valve (1, 100, 700, 800) for use in sterile fluid transfer has a body (5) with open entry and exit sides (2, 3) and a passageway (4) for fluid therebetween. The entry side is connectable to an opening of a separate vessel and the exit side is connectable to downstream processing. The entry side includes a first rupturable seal (5b, 500) blocking the opening of the entry side. A piston (9) is connected to an actuator (7) via a cam mechanism (8, 85, 10) which moves the piston (9) axially in the passageway (4) and to the first seal (5b, 500). On movement of the piston (9) during a first actuation, the first seal (5b, 500) is torn free from the entry side to open the valve for fluid transfer. A sharp rim (15) surrounds the opening of the entry side and a curved surface area (193) encircles the piston exterior proximal the entry side.

Abstract: A piston arrangement is disclosed for metering valves, flow-rate sensors or hydraulic motors. The piston arrangement comprises a housing, at least one recess in the housing, and a first piston sealed and movable in the at least one recess of the housing. A recess is provided in the first piston, and a flow passage extends through the first piston. A second piston is movable in the recess of the first piston. A sealing surface is provided on the second piston, and a valve seat is provided on the first piston against which the sealing surface on the second piston can be pressed in such a way that the second piston can be moved in the first piston between a position which opens the flow passage through the first piston and a position which shuts off the flow passage through the first piston.

Abstract: A two-step, self-regulating valve (16) controls gas flow from a gas cylinder (12) in a high pressure system. The valve (16) includes a valve body (24), a piston (26), a plug (28), a valve actuator (34), and a piston actuator (32). The piston (26) is movable within the valve body (24) along an axis between a first and a second position. The plug (28) is movable within the valve body (24) along the axis between a valve closed position, a partially open position, and a fully open position. The valve actuator (34) allows the plug (28) to move from the valve closed position to the partially open position. The piston actuator (32) causes the piston (26) to move from the first position to the second position when a gas pressure in the gas cylinder (12) is less than a setpoint. When the piston (26) moves to the second position, the piston (26) allows the plug (28) to move from the partially open position to the fully open position.

Abstract: A valve comprising a body portion, a closure portion adapted to control the flow of fluid through the body portion, and a valve element being at least disposed between the closure portion and the body portion. The invention extends to other arrangements detailed herein.

Abstract: A piston and valve stem assembly is held in either a gate open or gate closed position by a valve gate piston retention device until such time as sufficient air pressure is built up behind the piston, upon which the valve gate piston retention device is signaled to release the piston. The piston, being pre-charged, is thereby able to overcome both static and dynamic friction thus allowing it to move freely and immediately, and in the case of multiple pistons, simultaneously or sequentially, and without hesitation. Both simultaneous or sequential retention and release of the piston via mechanical or electromagnetic means can be controlled to actuate a plurality of pistons forward or back in an expeditious manner to overcome pneumatic losses and frictional forces in an effort to achieve more precise timing of the valve stem and optimize overall cycle time.

Abstract: Operability and lifespan of a drain valve of an operated infusion device are improved when changing the composition of a transported solution or releasing the pressure. A sealing portion and a shaft portion of the valve are constructed to be separated from each other. The shaft portion is disposed with a through hole having a step. A screw passes through the through hole, such that a screw portion of the screw is screwed to the sealing portion, and on the other hand, a screw head is fastened to the step portion of the through hole of the shaft portion. The sealing portion and the shaft portion can ensure a degree of freedom of rotation while maintaining a fixed position relationship there-between, thereby preventing the sealing portion from falling off and prolonging the lifespan of a valve body.

Abstract: A dosing apparatus in a form-fill-seal packaging machine comprises a delivery nozzle (12), a valve closure member (34) co-axial with the nozzle (12) and reciprocable co-axially relative thereto and bounding with the nozzle (12) an annular volume (35) therebetween for flow of liquid therethrough, fins (54) in the volume (35) and extending helically co-axially with the nozzle (12) for imparting a spiral motion to the liquid flowing through said volume, an annular valve closure seat (42) in and co-axial with the nozzle (12), respective annular portions of the seat (42) and the member (34) coming into sealing contact with each other, the annular portion of the member (34) comprising glass-fibre-reinforced plastics, a tubular bellows (44) extending between the nozzle (12) and the member (34) and sealingly separating in a liquid-tight manner the volume (35) from an interior chamber (46), and ducting (49, 50) which serves to supply a microbiocidal medium to the chamber (46).

Abstract: A plug body housing 16 has a receiving recess 17 and the receiving recess 17 includes a first recess 21 opening toward the outside and a second recess 22 connected to the first recess 21. Check valves 8 and 9 are provided in the second recess 22, and a manual valve 14 is provided in the first recess 21. An internal threaded portion 45 is formed in an inner circumferential surface of the first recess 21, and a housing 35 of the manual valve 14 is threaded into the internal threaded portion 45. The check valves 8 and 9 are held between a bottom surface 22a of the second recess 22 and a bottom 35a of the housing 35 so that the check valves 8 and 9 are secured in the second recess 22.

Abstract: A pneumatic toy gun includes a pneumatic assembly and an air valve. The pneumatic assembly has an air intake duct to receive high pressure gas and includes a first duct, a rear push rod, a front push rod and a harness element. A first gas chamber is formed between the rear push rod and the first duct. A second gas chamber is formed between the front push rod and the first duct. The second gas chamber has a second thrust surface smaller than a first thrust surface of the first gas chamber. The front push rod has a recess. When the front push rod is moved and the recess is located beneath the first sealing element, the second gas chamber communicates with an air outlet through the recess. The pneumatic toy gun of the invention can provide a strong instantaneous blast force without increasing battery voltage.

Abstract: The present invention relates to a three-in-one valve comprising an inlet shutoff valve for shutting off flow to an inlet of the valve, an outlet shutoff valve for shutting off flow into an outlet of the valve and a control valve for opening and closing the valve. During operation, the control valve can be opened and closed while the inlet shut off valve and outlet shut off valve are in an open position. The inlet shutoff valve and outlet shutoff can be closed for preventing flow into the control valve, thereby allowing the control valve to be serviced without draining of an attached fluid system, such as a radiator. In one embodiment, the three-in-one valve can be used to provide individual zone control for an individual radiator in a multi-radiator and boiler recirculating system.

Abstract: In a valve device for selectively opening and closing a flow passage formed to open on a valve seat by a valve body through a resin-made seat, a hollow portion is formed on either one of the valve body and the valve seat and receives the resin-made seat therein, the resin-made seat has a thickness so that the resin-made seat partly protrudes from the hollow portion, and when the valve body is operated to close the flow passage, the resin-made seat is compressed to bring an end surface of the valve body into contact with the valve seat.

Abstract: A double action directional fluid flow valve includes a stepped piston connected with a poppet valve and moveable by a controller between open and closed positions by applying a continuous pressure to a small diameter piston face and selectively applying and removing pressure from a large diameter piston face to move the poppet valve between an open position and a closed position.

Abstract: A fluid flow control device includes a body defining an inlet, an outlet, and a fluid flow path extending from the inlet to the outlet. A valve seat ring is coupled to the body and defines an orifice through which the fluid flow path passes. A cage is also coupled to the body and defines an interior bore, wherein the cage includes at least one passage through which the fluid flow path passes. A throttling element is sized for insertion into the cage interior bore and movable along an axis between open and closed positions. The throttling element defines a sealing surface oriented substantially parallel to the axis. A seal is positioned to engage the sealing surface when the throttling element is substantially in the closed position, thereby to restrict fluid flow through the valve seat ring orifice.

Abstract: A valve body has an annular bottom face and an inner circumferential periphery both defining a seat fitting hole, which is coaxial with a sliding hole. A spool is axially movable in the sliding hole. A seat member has an axial end surface and an outer circumferential periphery, which are respectively axially and radially press-fitted to the annular bottom face and the inner circumferential periphery to respectively define an annular seal portion and a cylindrical seal portion therebetween. The seat member has a bleed port for draining fluid from a bleed chamber. The spool has an end surface, which defines a small clearance between the end surface and the seat member when the spool is seated to the seat member for communicating a supply port with the bleed chamber.

Abstract: A valve gate piston assembly, in an injection molding system, is positioned in a staggered arrangement such that one piston assembly overlaps that of another valve gate piston assembly thereby minimizing an overall centerline pitch between said piston assemblies. Such a superposed layout of piston assemblies enables larger diameter pistons to occupy a smaller footprint than would be realized should the same piston assemblies be positioned side by side. The use of relatively larger diameter pistons results in an increased force available, for the same input air pressure, to actuate the pistons and valve stems attached thereto, resulting in a higher valve stem closing force. A staggered piston assembly layout also allows independent air circuits to control each piston separately. A combination of multiple piston assemblies may be configured in such a staggered, overlapping array.

Abstract: A controlling valve includes an outer sheet, an end cap and a control valve group. The control valve group is disposed between a flowing bore in the outer sheet and a water bore in the end cap. The controlling water valve is connected with the outlet of a water tube. When the control valve group is pushed upwards, the water bore in the end cap and the flowing bore in the outer sheet are closed in a predetermined sequence, then the water in the tube will not flow out. When the control valve group is pushed downwards, the flowing bore in the outer sheet and the water bore in the end cap are opened, then the water will flow out. When the water is stopped, the occurring positive or negative pressure wave is lowered, and then the vibration and the raspy noise will be avoided.

Abstract: A plumbing fitting which includes an inlet pipe connectable to a water supply pipe and an outlet connectable to an appliance, said fitting also including a valve arranged between said inlet pipe and said outlet, said valve being moveable between a first position in which water can flow from said inlet pipe to said outlet, and a second position in which said inlet pipe is shut off from said outlet, characterised in that in a first configuration of the plumbing fitting the outlet does not protrude beyond the profile of the inlet pipe.

Abstract: An adjusting valve adjusting valve for adjusting the delivery volume of a displacement pump includes a valve casing, a valve piston which is mounted such that the valve piston can be moved within the valve casing, a valve spring which counteracts a force exerted by the valve-actuating pressure on the valve piston, and an adjusting device serving to adjust the valve piston in the direction of or counter to the force exerted by the valve-actuating pressure. A displacement pump exhibiting an adjustable delivery volume, includes a pump casing, a delivery chamber formed in the pump casing and a delivery member and the adjusting valve for adjusting the delivery volume, arranged in a flow of the fluid delivered by the delivery member.

Abstract: A valve part of a hydraulic control valve for controlling flows of pressurized medium is provided, wherein the valve part includes a cylindrical valve housing with a first cylinder casing section extending in the axial direction and a first cylinder base section extending perpendicular to the axial direction, with the sections defining a valve housing hollow space that is open on one side. The first cylinder casing section is provided with a first work connection, a second work connection, and a pressure connection, each of which open into the valve housing hollow space. A cylindrical control piston is held in the valve housing hollow space so that it can move in the axial direction, and has a second cylinder casing section extending in the axial direction and a second cylinder base section extending perpendicular to the axial direction, with these sections defining a control piston hollow space that is open on one side.

Abstract: A fluid valve arrangement (10) having a valve housing (11), which has at least one passage (14, 15, 16) for the fluid (F), and having a valve body (12), which is arranged movably in the valve housing (11), for opening and closing the fluid passage (14, 15, 16), the valve body (12) being movable to and fro in the valve housing (11) between two closing positions and, in the central positions between the closing positions, freeing the fluid passage (14, 15, 16).

Abstract: A pin valve assembly and a method of controlling the flow of fluids comprising a pin block housing pin valves, a fluid plate with a fluid channel for fluidically communicating with the pin valves, and a fitting block housing fittings for fluidic communication with the fluid plate and for fluidic communication with fluidic components. The fluid flow through the channels of the fluid plate are controlled by the fluidic components and the pin valves.

Abstract: A valve device (10), in particular for use in fire fighting, comprises a valve and a safety mechanism by which the valve can be closed. The valve is a pilot-controlled piston valve.

Abstract: A valve is provided for controlling the flow of fluid through a valve block. The valve block has a fluid inlet port, a fluid outlet port, and a receiving bore for receiving the valve. The receiving bore hydraulically connects the fluid inlet and outlet ports, and has a central axis. The valve comprises a valve seat for placement between the fluid inlet and outlet ports, wherein the valve seat comprises a central axis which coincides with the central axis of the receiving bore, and wherein the valve seat further comprises an upper end overmolded by a valve seat attachment end of a plastic valve housing. The valve also includes a tube which comprises a central axis which coincides with the central axis of the receiving bore, wherein the tube further comprises a lower end overmolded by a tube attachment end of the valve housing.

Abstract: A valve for an anti-lock brake system is capable of reducing the cost of production through structural improvement of a valve housing. The valve includes a valve core, an armature located below the valve core and having a ball, a cylindrical sleeve coupled to the valve core and armature and guiding the armature to move backward and forward, a first elastic member installed between the valve core and the armature, a valve housing coupled to the sleeve and having a longitudinal hollow space, a seat plunger movably installed in the hollow space and having a first orifice, a second elastic member installed between the seat plunger and the valve housing, a seat having an outlet and a second orifice that communicates with the first orifice, and a seat housing coupled to the valve housing and the seat, supporting the valve housing and the seat spaced apart from each other, and having an inlet between the valve housing and the seat.

Abstract: The present invention relates to gas controlling and blocking valves and An automatic warm water circulator using the same, and includes a circulation cycle formed such that a reservoir is connected to a boiler by a supply pipe, the boiler is connected to a heat exchanger by a discharge pipe, and the reservoir is connected to the heat exchanger by a circulation pipe, a hollow combustion chamber provided in the lower side of the boiler and having both sides protruded toward the outside of the boiler, a gas supply and ignition device for supplying the gas to the inside of the combustion chamber and for burning the gas to heat water in the boiler, and a supply valve and discharge valve respectively provided in the supply pipe and the discharge pipe and automatically opened and closed in response to the inner pressure for the boiler.

Abstract: A connector includes a housing disposed in conjunction with a pressurized vessel and sprung valve assembly and a stem to be inserted into the housing in two stages. The stem is retained in the housing in the first stage and the stem activates the valve to release the pressurized fluid in the second stage. The connector employs a two-stage retaining mechanism that includes a clip retained in a groove defined in an interior wall of the housing, a lower groove and an upper groove formed into an exterior of the stem. The clip is disposed in the lower groove and the housing groove in the first stage; and in the upper groove and the housing groove in the second stage. The stem defines a stem stop that contacts an assembly setting mechanism upon completion of the first stage. The assembly setting mechanism is removed to allow the second stage.

Abstract: An actuator housing including an elongated body having a flange, an end portion and a sealing portion, wherein the elongated body, including the flange, the end portion and the sealing portion, is formed from a single and continuous piece of material.

Abstract: The present invention relates to piston seats disposed in housings for the management of exhaust gases, particularly those in exhaust gas valve assemblies. The present invention provides an exhaust gas valve assembly having a piston housing seat that is decoupled from the housing and a seal between the seat and the housing thus eliminating or reducing the escape of exhaust gases. The invention is particularly applicable where temperature cycles occur and affect components, such as automotive applications.

Abstract: A oneway valve for an automatically inflatable air cushion includes a valve body having an air inlet port and an air outlet port, a valve seat mounted in the valve body and formed with a plurality of conducting holes connected to the air inlet port and the air outlet port, and a valve stem movably mounted in the air inlet port and movable to seal the conducting holes. Thus, the oneway valve prevents the air from leaking from the air cushion during the inflation process and prevents the air from entering the air cushion during the deflation process, so that the air cushion is inflated and deflated completely and exactly.

Abstract: A sliding seal arrangement in particular for a valve having an anodised aluminium coating in contact with the seal. The coating is produced so that inclusions in the surface of the coating are substantially aligned. The direction of motion of the sliding seal in use is then substantially aligned with the direction of the inclusions resulting in greatly reduced wear on the seal.