Abstract: Provided for may be a motor speed control apparatus for use with a piston pump. The piston may be adapted to create a plurality of compressions and the piston may have a compression path and a decompression path. Further, the piston cylinder may include a proximal end, a distal end, and a piston length. The piston cylinder may have a proximal threshold position and a distal threshold position. In an embodiment, the apparatus includes a proximal and a distal hall effect sensor. The apparatus may comprise a computer, wherein instructions instruct the piston to decelerate at the distal threshold position during the compression path and the proximal threshold position during the decompression path, and/or wherein the computer executable instructions instruct the piston to accelerate at the distal threshold position during the decompression path and the proximal threshold position during the compression path.

Abstract: A blow-off metering valve for a hydraulic control unit assembly of a brake system including a valve seat. The valve seat includes a wall that extends about an axis between a first end and a second end. The wall defines a passage that extends axially between the first and second ends for transmitting a fluid through the valve seat. An annular flange extends axially from the second end of the wall toward the first end of the wall and tapers radially inwardly. A blocking member is axially movable toward and away from the annular flange for selectively creating a seal at the passage. A biasing element biases the blocking member toward the annular flange. The annular flange terminates at a distal end that is radially spaced from the wall. The annular flange defines at least one flow channel that extends axially for allowing fluid to bypass the blocking member.

Abstract: A relief valve has a valve body, a plunger assembly coupled to the valve body for selectively opening and closing the relief valve, and a support member secured to the valve body. A lockout lever is against the support member, forming a vertex. A spring rod is coupled to the lockout lever, and a spring is coupled to the spring rod, providing a bias force against the plunger assembly to normally close the relief valve. In a lockout position, the lockout lever is moved to pivot on the vertex against the support member to further compress the spring, which increases the bias force and, in turn, a cracking pressure of the relief valve.

Abstract: An overflow valve is built into a metering head for a metering pump used with aggressive media and under high pressure. The overflow valve follows the suction valve or expands it, and directly lowers a critical pressure that occurs in the metering head, using an overflow line. In this way, the safety of the arrangement is improved, and at the same time, less construction space is used up by the additional valve.

Abstract: A valve of the present disclosure includes a valve seat formed with a valve hole; a spherical valve body; and a pressing member that presses the valve body toward the valve hole, the valve hole being closed by the valve body pressed by the pressing member; where the pressing member includes a guiding part that, when a force opposing the urging force acts on the valve body by greater than or equal to a prescribed value, separates the valve body away from the valve seat while guiding and relatively moving the valve body in a predetermined one direction.

Abstract: Apparatuses manage the flow of fluids, such as, for example, water, through pipes. Specifically and without being bound by theory, the apparatuses of the present invention creates a backward pressure in fluid traversing a pipe, wherein the backward pressure within the pipe provides compression to the fluid effectively compressing entrapped gas bubbles within the fluid, allowing more accurate water meter measurements. The apparatus comprises a two-stage poppet valve for regulating the flow of fluids through a pipe.

Abstract: An apparatus for use in marine platform jacking is disclosed herein. In one aspect, a jetting valve includes a valve body with a piston assembly disposed therein. The piston assembly is selectively operated to open and close the valve. A biasing member is coupled to the piston assembly. The piston assembly includes a first piston and a second piston. The dual pistons, in cooperation with the biasing member, allow the valve to self-seal thereby preventing entry of a fluid which is external to the valve.

Abstract: Poppet valve for a piston compressor, having a valve body with a plurality of inlet ducts, wherein each inlet duct has an inlet section and an outlet section. The outlet section opens into a valve seat, wherein each inlet duct is assigned a closing element and a spring. The closing element can be moved in an axial direction (A) in such a way that the valve seat can be closed by way of the closing element. The spring has a first spring end section and a second spring end section, wherein the spring is arranged in the inlet duct and bears with the first spring end section against and is held on the inlet section of the inlet duct. The second spring end section is connected to the closing element, to bring about a pre-stressing force on the closing element, which pre-stressing force is oriented towards the valve seat.

Abstract: A venting outlet (1) for a drinking water supply system of an aircraft is proposed, having an inlet opening (3) which is arranged on a rear side of the venting outlet and is intended for receiving a venting fluid, in particular air, from the drinking water supply system, and further having a venting opening (6) arranged on a front side of the venting outlet and intended for discharging at least some of the received venting fluid to an external surroundings of the venting outlet (1).

Abstract: A knob assembly includes a front panel, a knob located at a front side of the front panel and configured to rotate based on operation by a user, a knob shaft that is coupled to the knob and that extends through the front panel, a supporting pipe that receives the knob shaft and that supports the knob shaft, the supporting pipe being configured to maintain a position relative to the front panel, a valve configured to control supply of gas to the appliance, a valve shaft connected to the valve and configured to control the valve to adjust a flow rate of gas based on rotation of the valve shaft, and a joint that couples the knob shaft to the valve shaft and that is configured to transfer at least one of a rotational motion or a linear motion of the knob shaft to the valve shaft.

Abstract: The invention relates to a bypass valve (1), in particular for an expansion machine (104) of a waste heat recovery system (100). The bypass valve (1) has a housing (2) with a valve chamber (9) formed therein. An inlet (3), an expander outlet (4) and a bypass outlet (5) are formed in the housing (2), which feed into the valve chamber (9). A closing element (6) is moveably arranged in the valve chamber (9). A valve seat (11) is formed on the housing (2). The closing element (6) cooperates with the valve seat (11) in order to open and close a first hydraulic connection from the inlet (3) to the expander outlet (4). A control valve (8) opens and closes a second hydraulic connection from the inlet (3) to the bypass outlet (5). The control valve (8) forms a first throttle point (21) in an open position. A second throttle point (22) is arranged between the valve chamber (9) and the bypass outlet (5). The control valve (8), the second throttle point (22) and the closing element (6) border a control chamber (9a).

Abstract: A suction dampening device comprises a housing with an inlet port formed therein and a valve case disposed adjacent the inlet port. The valve case includes at least one opening formed therein. A valve core is slidably disposed within the valve case. A lever having an axis of rotation fixed to a portion of the valve case includes a first lever arm disposed to a first side of the axis of rotation and a second lever arm disposed to a second side of the axis of rotation. The second lever arm abuts an outer circumferential surface of the valve core. A spring element is disposed between the first lever arm and the valve core. The spring element is configured to apply a force to the first lever arm to cause the second lever arm to apply a lateral force to the valve core to dampen vibrations of the spring element.

Abstract: A valve assembly that includes a valve body, a poppet member, and a biasing member. The valve body has an internal through-channel. The poppet member has an inside portion positioned at least partially inside the through-channel and an outside portion positioned outside the through-channel and extending outwardly beyond the valve body. The poppet member is movable within the through-channel between an open position and a closed position. The biasing member is external to the valve housing and applies a biasing force to the outside portion of the poppet member that biases the poppet member toward the closed position.

Abstract: A device for the preparation of a beverage includes a beverage supply duct and a closure element. The closure element includes a closing surface suitable for closing at least partially an end of the supply duct. The device is characterized in that the closure element is made of elastomer material suitable for undergoing an elastic deformation under the thrust of the beverage being supplied. The deformation causes an at least partial movement of the closing surface away from the end of the supply duct.

Abstract: An infused beverage brewing assembly that includes a solvent flow management system (SFMS) operable to receive a solvent and then at least one of modulate and maintain a flow of the solvent independent of a back pressure within a brewing chamber for housing a solute disposed to receive the solvent to produce an infused beverage, wherein the SFMS is in fluid communication with the brewing chamber through at least one solvent conduit, the assembly including an outlet for discharging the infused beverage and having an electronic control system communicatively coupled to and operable to selectively modulate the SFMS to at least one of modulate and maintain the flow of the solvent upstream of the brewing chamber and downstream of the SFMS independent of the back pressure without the use of a feedback mechanism for monitoring the flow of the solvent.

Abstract: A hydraulic overpressure valve (1) is provided comprising a valve housing (2), a valve seat (3) located in said valve housing and having a seat center and a seat center axis (4), a cone element (5) movable relatively to said valve seat (3), said cone element (5) having a cone (6) protruding at least partly into said valve seat (3) and having a cone center axis (4), and force generating means acting on said cone element (5) in a direction towards said valve seat (3). Such a hydraulic overpressure valve should be operated with low noise. To this end said cone (6) is movable along a path of movement in which said cone center axis is kept outside said seat center axis (4).

Abstract: A seal arrangement for a housing for receiving a battery has a valve arrangement for compensating a pressure differential between an interior of the housing for receiving a battery and an environment outside of the housing for receiving a battery. A desiccant is provided for removing moisture from a gas contained in the interior or gas that flows into the housing for receiving a battery. A chamber is provided that is connected to the valve arrangement and that contains the desiccant, wherein the chamber and the valve arrangement are in gas-conducting communication with each other.

Abstract: An explosion vent mounted to seal an opening formed on a wall of a closed space comprises a cover being dimensioned to fit on said opening and having a perimeter with an edge adapted to seal the cover against the opening with a sealing element. A spring element is arranged to hold the cover in the opening and the spring element has a direction of spring action. The cover is held by opposite retaining surfaces in the opening and the cover and he retaining surfaces are acting against the spring action of element. The sealing element is positioned against the opening so that the sealing force is directed at least partially crosswise to the direction of the spring action of the spring element.

Abstract: An infused beverage brewing assembly that includes a solvent flow management system operable to receive and convey a solvent, a solvent temperature management system in fluid communication with the solvent flow management system and operable to modulate the temperature of the solvent, a brewing chamber for housing a solute disposed to receive the solvent to produce an infused beverage resulting from an infusion process, an infusion pressure regulation system with at least one pressure regulation component located downstream of the brewing chamber, operable to selectively and dynamically modify an infusion process pressure greater than a pressure created upstream in the brewing chamber caused by a flow of the solvent through the solute, and operable such that the flow of the solvent through the solute is not singularly contingent on a pressure differential across the at least one pressure regulation component, and an outlet for discharging the infused beverage.

Abstract: A valve unit for a motor vehicle having a valve housing, which includes a valve inlet and a valve outlet, and having a valve body disposed in the valve housing, which includes a cross-section, increasing up to an inflection point and decreasing once past the inflection point, and which is guided from a closed position in which the valve body seals the valve inlet to a final opened position in which the valve body abuts a stop element fixed in the valve housing, releasing the valve inlet, and in which an inflow section is formed between the valve inlet and the inflection point of the valve body, and an outflow section is formed between the inflection point of the valve body and the valve outlet.

Abstract: Described herein is an improved externally mounted pressure relief valve that is especially adapted for rail tank cars or other large closed containers that contain or transport fluids, including liquids and gases. The pressure relief valve comprises a plurality of spring assemblies, and each spring assembly contains a pre-determined number of spring leaves. Each spring assembly is coiled upon a corresponding spring drum, and each spring drum is penetrated by a corresponding spring drum bolt. The spring assemblies are preferably aligned in at least two horizontal planes that are parallel to each other and normal to the vertical length of a spring block. The spring block and sealing disk are mounted vertically over the valve seat and within the confines of vertically extending spring brackets.

Abstract: A spout and fitment assembly for a flexible bag. The spout comprises a base flange, a cylindrical upstand and a fitment coupling. The base flange is configured to be coupled to a flexible bag. The cylindrical upstand extends from the base flange. The cylindrical upstand defines a passageway therealong which is placeable in fluid communication with the flexible bag. The fitment coupling extends from the cylindrical upstand between the proximal end and the distal end thereof. The fitment assembly comprises a fitment body and a hose. The hose is coupled to the hose connection portion. The connector portion is sealingly engaged with the fitment coupling so as to place the inner bore in fluid communication with the passageway of the cylindrical upstand.

Abstract: A smart drain valve comprises a support plate, a bolt passing through a center of the support plate, an outer plate connected to a first end of the bolt, an inner plate connected to a second end of the bolt, and a spring positioned between the inner plate and the support plate. The spring is made of a shape memory material.

Abstract: The invention generally relates to a flow control device and a flow control methods.

Abstract: Disclosed herein is an improved method for reversed flow through a self-adjustable (autonomous) valve or flow control device (2), comprising the step of providing an overpressure on the side of the valve (2) opposite of the side of the inlet (10) exceeding a predetermined biasing force of the resilient member (24) causing lifting of the inner body part (4a) within the outer body part (4b) against said biasing force from a first position of fluid flow between an inner and an outer side of the valve (2) via the flow path (11) and to a second position of reversed fluid flow between said inner and outer side through the second flow path (25). An improved self-adjustable (autonomous) valve or flow control device (2) and use of said improved valve or flow control device are also disclosed.

Abstract: A fluid control valve includes an inflow channel for introducing fluid, an outflow channel for discharging the fluid, a valve seat, a valve body for blocking/allowing communication between the inflow channel and the outflow channel in association with a movement thereof into contact with or away from the valve seat, and a solenoid configured to apply a magnetic force to the valve body, the magnetic force being generated in response to supply of electric power to the solenoid. The inflow channel is formed through the core of the solenoid so that the core and the fluid comes into contact with each other in the inflow channel.

Abstract: A check valve (100) has a valve seat (20), and a valve disc (30) which closes the valve seat (20) in an openable/closable manner by linear reciprocating oscillation in the direction approaching or departing away from the valve seat (20), the check valve (100) being configured, as a lift-type check valve, to allow therein the inflow direction (D1) of a fluid (F) flowing into the valve seat (20) and the passing direction (D2) of the fluid (F) passing through the valve disc (30) to cross each other, the valve disc (30) being provided with, on the inflow side (primary side) thereof, a deflection surface (40) on which the fluid (F) is deflected from the inflow direction (D1) to the passing direction (D2).

Abstract: A device for limiting the feed of fuel out of a high-pressure supply via a controllable injector into the combustion space of an internal combustion engine comprises a housing including a pressure supply-side housing inlet, an injector-side housing outlet, and at least one duct having a throttle, and a closing member longitudinally displaceable in a chamber between an initial position and an end position, spring-prestressed opposite to a flow direction, and configured to control a flow connection between the housing inlet and the housing outlet. The housing inlet is connected to the housing outlet via the at least one duct, and the at least one duct runs radially outside the chamber.

Abstract: A valve assembly for a tank of a vehicle and a method of creating a vacuum are disclosed. A valve body defines a cavity and an outlet in fluid communication with the cavity for venting the tank. The assembly includes a seat disposed in the cavity of the valve body. The seat separates the cavity into first and second cavity portions. The seat defines an aperture to provide fluid communication between the first and second cavity portions. The assembly includes a cover device disposed between the seat and the outlet. The cover device defines at least one hole therethrough. The cover device is movable between a rest position engaging the seat to minimize fluid communication between the aperture and the hole and an actuated position spaced from the seat to increase fluid communication between the aperture and the hole when a vacuum is created in the first cavity portion.

Abstract: A medical valve having a valve inside housing and a valve core. The valve core is installed within the housing. The housing is preferably an integrally-formed hollow cylindrical structure. An annular protrusion may be arranged on the outer surface of the housing and a seal ring may be arranged in the center of the inner wall of the housing. The valve core can be made of an elastic material as an integrally-formed cylindrical structure. A lock ring matched with the seal ring of the housing may be arranged on the outer surface of the valve core, and the lock ring can be integrally formed with the valve core. The medical valve inside disclosed by the invention is widely applied to the medical fields such as cushion mask, trachea cannula and laryngeal mask, No metal member is preferably employed, so with magnetic resonance imaging examination without causing interference.

Abstract: A gas pressure regulator is disclosed that includes a reciprocating piston that engages and disengages from a seat to open the higher pressure and lower pressure sides of the regulator to one another. The regulator includes an elastomer seal between the seat and the piston that has an ignition rating sufficient to avoid combustion in the presence of oxygen at pressure differentials that are a factor of between 5 and 10 between the higher pressure and lower pressure sides of the regulator.

Abstract: An assembly includes: a first component; a second component enclosed by the first component; a diaphragm that covers a radial gap between the first and second components and is fixed in each case in a sealed manner; and a volume of a medium that is enclosed by the first and second components and the diaphragm. For the purpose of achieving a simple filling process of the assembly with the medium at a reliable sealing of the enclosed volume, even in the case of high, swelling pressures acting upon the assembly, in one of the components a filling valve is situated that opens towards the volume, which filling valve is situated as a check valve having spring resetting in a filling channel running in the component.

Abstract: A valve element in a valve chamber is movable between an OFF position and an ON position to switch a flow quantity of fluid between a large flow quantity and a small flow quantity. The valve chamber has a fluid passage including an outer passage defined between an inner periphery of the valve chamber and an outer periphery of the valve element. The valve chamber has a throttle shape to decrease in inner diameter gradually from upstream toward downstream to decrease a minimum passage area of the fluid passage in a non-linear form. The valve chamber increases a differential pressure across the valve element in a linear form relative to a stroke of the valve element when the valve element moves from the OFF position toward the ON position.

Abstract: A control valve includes a piston-housing having a hollow portion. The hollow portion has a first end, an open end, first and second internal chambers, and a fluid port configured to allow fluid to exit the second chamber. The first chamber is nearer the first end, and the second chamber is nearer the open end. A piston is located within the housing and is adapted for reciprocal motion. The piston includes a first and second seal-engaging portions. The first seal-engaging portion has a diameter that is less than the diameter of the second seal-engaging portion.

Abstract: A valve housing receives a spool and the spool has a regulating chamber selectively communicating a supply line to a return line. The spool is biased in one direction by a spring force and there is a second force biasing the spool in an opposed direction with the second bias force being provided by a fluid pressure within a hydraulic system associated with the pressure regulating valve. The amount of communication between the supply port and the return port is regulated by a position of the spool as the bias force from the fluid pressure change. Damper chambers are provided on opposed sides of the spool and serve to dampen a speed of movement of the spool and a supply line for supplying fluid into the damper chambers through check valves. The supply line serves to assist in purging air outwardly of the damper chambers.

Abstract: A tube coupling device includes a coupling member having a lower casing and an upper housing and a peripheral flange extended between the casing and the housing, a water guide plate is engaged into the housing and has one or more off-center passages, a partition member is engaged in the housing and includes a pathway for the water to flow from the water guide plate and into the casing, and the partition member includes an inclined inner peripheral surface formed around an upper recess for defining an inner peripheral projection and for engaging with the water guide plate and for anchoring and retaining the water guide plate in the housing, a receptacle is engaged in the casing for preventing the materials in the coupling member from being released into the water.

Abstract: Devices and methods for extracting a beverage from a container, such as a wine bottle. Beverage can be extracted from a container by inserting a needle through a container closure, such as a cork, delivering pressurized gas into the container via the needle, and dispensing beverage from the container via the needle. A pressure regulator may control a pressure of gas introduced into the container, and a lance used to pierce a pressurized gas cylinder may include a leading face arranged to reliably pierce a cylinder closure. The regulator may include valve features to reduce valve chatter or hammering and provide a more reliable pressure seal.

Abstract: A spring mounting cradle for an over-pressure valve assembly has integral valve-element camming surfaces provided adjacent the lower ends of a pair of the bent legs forming the cradle.

Abstract: An actuator system for a fluid playground including a first elongated tubular member defining a first axially extending enclosure and having a first inlet connectable to a fluid source, and a second elongated tubular member positioned within the first tubular member, the second tubular member defining a second axially extending enclosure, and having a second inlet in fluid communication with the first enclosure and an outlet traversing the first tubular member. The outlet is connectable to at least one fluid playground device. A plug element is shaped to removably and sealably close the second inlet of the second tubular member. A resilient member urges the plug element towards sealing engagement with the second tubular member. A pressure exerted on a movable actuating element connected to the plug element causes its displacement away from sealing engagement with the second inlet, thereby allowing fluid flow to the fluid playground device.

Abstract: Relevant specifications in the field of gas supply provide for different safety devices for installation in a gas-supply system, in particular, an acetylene-supply system. To provide such a safety device, which is characterized by a compact structure and a high level of operational reliability, this invention proposes that a valve body (1) incorporates an over-pressure valve (4; 104) of a quick-action shut-off device, a control valve (3; 103) of a pressure-limiting device, and a safety valve (2; 102), whereby the safety valve (2; 102) can be fluidically connected to the over-pressure valve (4; 104) and the control valve (3; 103), and closes either when the over-pressure valve (4; 104) opens due to an inlet pressure that is above the inlet-pressure limit value or when the control valve (3; 103) opens due to an outlet pressure that is above an outlet-pressure limit value.

Abstract: A coil spring/relief valve and an oil filter assembly comprising an oil filter housing, filter media, and the coil spring/relief valve are provided. The coil spring/relief valve may comprise a valve assembly comprising a valve can, a sealing member, a relief spring, a coil spring that may be used to keep constant pressure against the filter media, and a pressure relief valve can. The sealing member and the relief spring can be mounted on the pressure relief valve can. The coil spring and the pressure relief valve can may be held together as a one piece assembly within the oil filter housing. The valve can receives the coil spring, which can be supported by the oil filter housing, to force the valve can into contact with the oil filter media with a constant pressure.

Abstract: A rapid response self-closing pressure equalization vent employs a frame supported in a compartment divider and a movable vent portion having a periphery sealingly engaging the frame in a closed position. Multiple resilient extension elements are attached to the frame and engage the movable vent portion for even displacement around a periphery of the movable vent portion relative to the frame to an open position responsive to a pressure differential on the movable vent portion. The resilient extension elements retract upon equalization of the pressure differential to reseat the movable vent portion in the frame.

Abstract: Embodiments of the invention provide a normally open valve, a normally closed valve, and a combination valve. The valves include a valve body with an inlet coupled to a fluid supply line, an outlet providing a service flow of fluid, a vent venting to atmosphere, a lower piston, a lower diaphragm, and a mechanical valve actuator. The mechanical valve actuator includes an upper piston, an upper diaphragm, a pilot piston with a bore and a plunger, and a spring. The spring is positioned either inside the pilot piston for the normally open valve or inside the upper piston for the normally closed valve. The valves are actuated based on a control fluid entering a system pressure port and exceeding a pressure set point in order to either open or close the valve.

Abstract: A double check valve is provided that includes an in-line inlet check valve and an outlet check valve that cooperate to prevent back flow of fluid through the valve. The check valve also includes at least one vent that allows for fluid trapped within the check valve to drain, thereby preventing freezing of the check valve and hydrant to which it is interconnected. The check valve provided omits many superfluous components and thus is smaller and easier to install than check valves of the prior art.

Abstract: A valve subassembly for arrangement on a valve device is disclosed. The valve subassembly includes a valve closing body configured to be placed on and raised from an associated valve seat. The valve subassembly also includes a return element configured to reset the valve closing body against the valve seat and a valve cover configured to close an associated valve housing. The valve cover, the return element, and the valve closing body are connected to one another in a captive manner.

Abstract: An embodiment of a flow control valve includes a housing and a valve member. The valve member is movable in an axial direction within the housing, so that a flow rate of a fluid flowing within the housing changes in response to a position of the valve member within a control range in the axial direction. A spring device biases the valve member in the axial direction, so that the valve member moves in the axial direction against a biasing force of the spring device according to a difference in pressure on an upstream side and a downstream side of the valve member. The spring device includes a spring constant that changes according to the position of the valve member in the axial direction within the control range.

Abstract: A first seal portion forms, when seated on a first seated position, a valve side chamber blocked from a relief chamber to have an equivalent fluid pressure to fluid pressure in a pressure-controlled chamber. The first seal portion causes, when lifted from the first seated position on increase in fluid pressure in the pressure-controlled chamber, the valve side chamber to disappear and to communicate the relief chamber with the pressure-controlled chamber. A second seal portion partitions, when seated on a second seated position, a part of the valve side chamber from the other part of the valve side chamber. The second seal portion is configured to be lifted from the second seated position on increase in fluid pressure in the pressure-controlled chamber, before the first seal portion is lifted from the first seated position.

Abstract: A pressure relief valve for a common rail fuel system includes a hard ceramic spherical valve member that moves into and out of contact with a conical valve seat of a soft metallic valve body. Fretting damage to the valve is inhibited by using the dissimilar materials, and by using a guide pin that is allowed to move on the spherical surface of the ceramic spherical valve member. The valve member may be constructed of silicon nitride.

Abstract: The present invention provides an improved pressure relief valve comprising a tubular main body with a pressure relief peroration, a pressure adjustor with an anti-leakage rubber and an anti-reverse unit; wherein the main body comprises a mount opening, an air outlet and a conduit between the air intake and outlet. The conduit comprises an abutting portion; the pressure adjustor is mounted on the air intake and the anti-reverse unit is fastened onto said outlet. As the pressure adjustor is connected to an air pump and said outlet is connected to an air-filling article, the pressure value of said article is set via the pressure adjustor. As said article reaches said pressure value, the anti-leakage rubber of the pressure adjustor is pushed such that air is released from the relief perforation and the anti-reverse unit abuts the staged portion of the conduit to maintain the article at a stabilized filling state.

Abstract: A check valve construction is provided having: a movable disc with a flat surface on a first side and a convex shaped surface on the opposing side, a first seat on for the flat surface and a second seat for the convex surface, where the narrowest portion of the fluid path is defined by the equation: G 3 = 12 ? ? ? ? W ? ? Q ? ? ? D ? ? ? ? ? P Wherein G: the gap of most narrow passageway between the flat surface of the disc and disc seat; ?: dynamic viscosity of the fluid; D: mean diameter of the flat sealing surface of the disc; Q: desired fluid flow rate; W: breadth of the flat sealing surface of the disc; ?P: pressure differential across the gap (G).