Abstract: A valve seat having a tubular valve seat wall portion that extends about a frusto-conical valve member that moves longitudinally into the valve seat to close a valve in which the seat and valve member are included. Coaxial openings are formed through the valve seat wall portion to provide for passage of fluids through the valve and at least one longitudinally extending groove is formed in the inner surface of the valve seat wall portion, to extend the length thereof, between the openings. A second groove can be formed in the inner surface of the wall portion opposite the first groove or, alternatively, a cut can be formed through the wall portion opposite the first groove. The valve seat can be locked against rotation by making the wall portion thereof square or providing the wall portion with an anti-rotation tab at one end of the wall portion or a notch formed through a flange at one end of the wall portion.

Abstract: A fluid flow control valve includes a valve body including a side wall, an inlet port through a portion of the side wall, a top, a bottom, a discharge port centrally located in the bottom, and an interior chamber; a piston slideably mounted within the interior chamber, the piston having one end overlappingly opposing the concentric with the discharge port, the one end having a centrally located recessed portion; a sealing member removably secured to, located within, the concentric with the recessed portion of the one end of the piston for providing a fluid tight seal between the piston and a valve seat about the circumference of the discharge port whenever the piston is positioned for closure of the valve; a throttle rigidly attached to and concentric with a portion of the sealing member, the upper portion of the throttle proximate the piston being cylindrical and having an outside diameter approaching the inside diameter of the discharge port, the lower portion of the throttle including a plurality of scallo

Abstract: A valve including rotor means of which position is rotatably fixed within tubular flowpassage means; rotating magnetic field generating means fixedly positioned around said rotor means; first screw means which are rotated coaxially with the rotor means together with the latter; second screw means which engage the first screw means and are movable in an axial direction of the screw without being rotated for itself by the rotation of the first screw means; valve body means connected to the second screw means; and valve seat means in engagement with the valve body means, whereby the rotor means are rotated by the action of the rotating magnetic field generated by the rotating magnetic field generating means, said rotation causes the second screw means to be moved in an axial direction of the screw, and said movement is transmitted to the valve body to adjust a degree of opening and closing of the valve.

Abstract: A variable steam control for a steam iron employs a metering rod having a plurality of cylindrical portions of successively decreasing diameters. A cam controls the position of the metering rod to position a selectable one of the cylindrical portions within a circular opening, whereby controllable water flow rates, and consequent steam flow rates are attained. The cam includes an assembly region having a cam-installation opening therein, usable following drop-in assembly, for enabling a head of a steam-control actuator rod to pass through the cam. A one-time movement of the cam locks the head in one of a plurality of user regions and blocks return to the assembly region.

Abstract: A back pressure regulator system is set forth. In the preferred embodiment, a pressure to be regulated is input to a pressure transducer. The transducer forms a signal indicative of pressure applied through a regulator system which forms an output driving differential signal suitable for a motor. An electric motor is driven thereby and operates a gear box which in turn connects through a slip clutch and a linear motion clutch to advance or retract a needle valve stem. The stem is threadedly engaged with the body. It rotates to advance or retract a needle valve in a valve seat, and a connection is made from the pressure to be regulated through the needle valve to thereby control back presssure on the system.

Abstract: A rising stem valve comprising a valve body, a two part valve stem and a stem guide washer. The valve body has a valve seat in a passage between an inlet and outlet port. The two part valve stem comprising a rotating stem and a non-rotating stem and the rotating stem has a threaded bore receiving a threaded end of the non-rotating stem. The non-rotating stem has a non-circular cross section external of the threaded bore and is adapted to carry a closure head to the valve seat. The stem guide washer has a bore positioned in mating relationship with the noncircular cross section of the non-rotating stem, whereby the stem guide washer prevents the stem from rotating when the upper stem is rotated.

Abstract: A control valve includes a pulse motor 1, the threaded shank 4 of a ball screw 3 connected to the output shaft 2 of the motor, a slider 6 united with a nut 5 on the ball screw 3, and a valve stem 8 extending outward from a valve assembly 7 and connected to the slider 6. Two cases 9 and 10, each in the form of a vertical cylinder having a bottom, are fitted together in vertical alignment, and the pulse motor 1 is placed on the upper end of the upper case 9 to close the end opening thereof, with the output shaft 2 extending into the upper case 9. The slider 6 is housed in the lower case 10 and has its peripheral wall coupled to the inner surface of the lower case 10 so as to be vertically slidable. The threaded shank 4 extends through and is rotatably supported by the bottom wall 22 of the upper case 9. The valve assembly 7 is fixed to the bottom wall 41 of the lower case 10.

Abstract: A flow control valve operable to bleed pressure from a pressurized source. The flow control valve includes an integral body, a bleed cap, a bleed valve element and a check valve assembly formed of a valve housing and a valve element.

Abstract: A wear monitoring device for use in a choke valve. The device includes a wear liner which fits in the flow annulus of the valve. The liner is sealed at either end from the fluid inlet valve and defines an annular void space in fluid communication with a port to the exterior of the valve. Leakage caused by flow cutting through the liner can be observed as fluid discharge from the port.

Abstract: An erosion resistant article is formed by cladding a substrate with tiles having a surface layer of polycrystalline material such as diamond or cubic boron nitride. The tiles may be entirely polycrystalline diamond or may have a backing of cemented tungsten carbide. Such an article can be trim for a high pressure valve wherein a sleeve is partly lined with polycrystalline diamond tiles and a plug is clad with polycrystalline diamond tiles.

Abstract: A water control valve in a wet air scrubbing device to discharge and direct water flow within the scrubber. The valve is composed of a conical valve body made of polyurethane and a fluid discharge receptor firmly attached to the air scrubbing device and connected to a water source. The conical valve body is movable into and out of engagement with the discharge repcetor. The conical valve body of the present invention is resistant to degradation by solvent vapor, resists contaminant adhesion and provides self-sealing engagement when the valve body is brought into contact with the discharge receptor.

Abstract: Method and apparatus for the control of fluid flow using a metering plug that is positioned in a control channel and restricted to movement along the longitudinal axis of the channel. Closure control is exercised by moving the plug with a micrometer adjustable control ring into closer proximity with a tapered channel that has a profile corresponding to that of the plug.

Abstract: A special control valve plug is disclosed. It includes the integral combination (1) of a spherical radiused or ball type seating surface and (2) a conically tapered flow control tip. When the valve is closed, the spherical radiused plug seating surface provides a positive fluid seal. When the valve is open, the tapered tip provides precise proportionate and continuously variable control of fluid flow.

Abstract: A dispense tape (10) to control the flow of carbonated beers is configured to minimize pressure drop and turbulence in beer flow to an outlet nozzle (14) when open, the tap having flow restrictor means (52) operatively connected as a downstream extension of the tap valve (30), located in the path of beer flowing from the valve, arranged only to affect beer flow when the tap is nearly closed and configured to substantially restrict beer flow to maximize pressure drop and turbulence; choice of nozzle length/bore ratio enabling either a creamy flow or a squib of beer to be dispensed.

Abstract: A control valve includes a valve box whose interior accommodates a valve needle closing against a valve seat. The interior of the valve box is subdivided in sections with at least two conical bores with different cone angles for improving the flow guidance and providing more uniform velocity distribution.

Abstract: The improved choke includes a body with an internal valve chamber, an inlet and an outlet communicating through the body into the valve chamber, a valve seat surrounding the opening of the outlet into the valve chamber, and a valve member mounted within said body to move toward and away from said valve seat to control flow therethrough, means for moving the valve member in said body, the valve member having a stem and a replaceable, wear-resistant tip which is provided with a sleeve insert secured within the stem opening and having internal threads which mate with external threads on the end of the stem, the tip recess includes a groove into which a portion of the sleeve insert is swaged to secure it tightly into the tip.

Abstract: High-pressure, micrometering valves requiring low-actuating torque are combined in a lightweight, portable pressure calibration console, housed in a common valve block. A manual pressure valve and a manual vent valve connect compressed gas from an internal storage cylinder to pressure measuring gages or transducers to be calibrated. Automatically actuated isolation valves connect and disconnect a vernier balancing cylinder assembly, permitting fine manual adjustment of calibration pressures as high as 10,000 psi. Positive shutoff combined with low-torque, fingertip control and non-jamming closure are provided by the frictionally-engaged valve components.

Abstract: At the time of expansion and accompanying kinetic degradation of a flowing stream of fluid, the flow is stabilized by forming at least two contiguous flow streams which consist of the same fluid but have a different velocity distribution and the two streams are then mixed. When applying the method to a valve provided with a so-called "hemispherical" closure member for compressible fluids, subsonic discharge nozzles are formed by cutting recesses in the valve seat downstream of the zone in which the valve closure member bears on the valve seat in the closed position. The subsonic discharge nozzles are disposed in alternate sequence with supersonic discharge nozzles formed by the opposite surfaces of the valve closure member and of the valve seat outside the recesses. When the method is applied to a multi-bore pressure reducer for compressible gases, a pressure-reducing plate is provided with low-discharge ducts in adjacent relation to high-discharge ducts.

Abstract: A metering valve having a one-piece bonnet for reducing problems resulting from tolerance stack up. A guide portion is included on the nose of the bonnet for cooperation with a valve body bore to ensure concentric alignment between the metering pin and its associated orifice. A pair of O-rings on the valve stem cooperate with the bonnet bore to absorb forces and substantially reduce the potential for galling and breakage of the metering pin. One of the O-rings is compressed to a substantially greater extent than the other to aid in achieving better alignment between the stem and bonnet, and to obtain a firmer feel.

Abstract: Simple cleaning, exact dosing and a high degree of operating safety are assured with a dosing device for dispensing a liquid through a liquid dispensing nozzle from a container holding the liquid under pressure in the interior thereof, which comprises a liquid dosing piston displaceable along the axis thereof and housed in a bushing having a screw thread for attachment to the container. The piston has a valve body at an end thereof adjacent the interior of the container and a section of reduced cross section adjoining the valve body, the valve body having a cylindrical surface coaxial with the piston.

Abstract: In the manufacture of a foamed confection such as foamed chocolate, a confection in liquid form is mixed with carbon dioxide under pressure and passed still under pressure to a depositor. The mixture is discharged from the depositor through annular outlet orifices which are opened and closed in turn by associated valves so that at any one time some of the orifices are discharging the mixture, and the number of orifices which are closed does not vary. Each annular orifice has a length which is not greater than its diameter. Each valve has an annular valve seat and a valve member movable into and out of engagement with the valve seat.

Abstract: A shutoff valve, includes a conical valve seat, and a valve disc movable toward the valve seat in a given direction, the valve disc including a base body covering the valve seat, an annular projection projecting from the base body in the given direction, and a rim formed on the outside of the projection resting against the valve seat in a closed position of the valve, the projection having a region with a given wall thickness in vicinity of the base body and the projection having a free end reinforced to at least 1.5 times the given thickness in the radial direction.

Abstract: A valve includes a body having a tapered protrusion on one end and a thin walled heel on the other end. A cap includes a shoulder about which the thin wall is flared to couple the cap to the body. A sleeve positioned on the body provides effective sealing between the body and a flow device.

Abstract: A needle valve having improved accuracy and wear characteristics is disclosed in which the valve stem is subjected to a constant force to prevent backlash throughout its entire movement with respect to the valve seat. In addition, the needle contained within the valve stem has a tapered end which moves within the cylindrical bore in a valve seat to control fluid passing through the valve and such needle is affixed to the valve stem only at its other end remote from its tapered end. The needle thus floats for a substantial portion of its length and its tapered end is relatively flexible and free of movement. The needle is, however, angled with respect to its valve seat such that the needle physically makes contact with the internal surface of the valve seat and maintains that contact throughout its lateral movement within the valve seat.

Abstract: A throttling and shut-off valve assembly for slurry pipelines and the like takes advantage of a gravity induced concentration and velocity gradient which develops in a substantially horizontal flow of coarse slurries. The throttling and shut-off valve assembly includes a conduit which is disposed substantially horizontally and wherein a valve body is mounted in an elongated streamlined housing to seat against a valve seat. The valve body is actuable to move substantially axially in the conduit. Both the valve body and the streamlined housing are disposed substantially along the longitudinal center line or axis of the conduit, which is upwardly offset relative to the longitudinal axis of the pipeline from which the flow is directed into the valve assembly. The bottom wall of the conduit is level with the bottom wall of the upstream portion of the pipeline.

Abstract: Hydraulic valves such as hydraulic flow control valves, pressure regulating valves, and servo valves are all formed with metering passageways which reduce and eliminate their susceptibility to electro-kinetic corrosion erosion that occurs at very low quantity flow and at very high velocity when the valves are in their null position or nearly shut off. The metering passages and the metering edges comprising the overall metering passageways are shaped to favorably control the flow characteristics of phosphate ester based fluids, which, if not controlled favorably would produce severe electrokinetic streaming current and its wall current, which would induce electrokinetic corrosion erosion. The shapes and dimensions of the metering passages and metering surfaces are derived from the results of a mathematical quantitative analysis.

Abstract: A valve for injecting fluid into a conduit carrying a slurry subject to separation to form deposits capable of plugging openings into the conduit. The valve comprises a valve body that is sealed to the conduit about an aperture formed through the wall of the conduit to receive the fluid to be injected and the valve member of the valve includes a punch portion that extends through the injection aperture to the flow passage, when the valve is closed, to provide a clear channel into the conduit, when the valve is opened, through deposits which might have formed on portions of the valve adjacent the conduit.

Abstract: A fuel control system for burners such as gasoline lanterns provides automatic tip cleaning and adjustable light output. The fuel system includes a burner, a fuel tank, and a fuel conduit for supplying fuel to the burner. A valve is interposed in the fuel conduit for opening and closing fuel flow. The conduit has a fuel outlet orifice, and a tip cleaning needle is reciprocable within the conduit for cleaning the orifice. The valve and the tip cleaning needle are controlled by a rotatable control shaft which extends perpendicularly to the conduit and which includes an eccentric pin. The eccentric pin extends above a valve block into a slot in an eccentric follower.

Abstract: A hydraulic choking device for use in controlling fluid flow from an oil or gas well, having an improved valve chamber and valve design to reduce parts' wear and facilitate repairs, wherein the chamber is provided with a cavity within the chamber passageway sidewall to which the fluids are initially directed and wherein a ball nose plug is utilized as the valve gate to seal the valve.

Abstract: Apparatus, and method, for controlling the flow of dilute solutions of polymers such as dilute aqueous solutions of partially hydrolyzed polyacrylamides without causing any significant degradation of the polymer comprising the solutions. In one embodiment, the apparatus comprises a needle valve positioned in a conduit for transporting polymer solutions, and across which a fluid pressure differential exists. In another embodiment, the apparatus comprises a self-adjusting flow regulator which incorporates a tapered, or pointed, throttle carried on a reciprocatable piston.

Abstract: A valve having a body with a valve chamber therein, an inlet into the valve chamber, an outlet from the valve chamber and an opening to the valve chamber aligned with the outlet, a bonnet secured to the body covering the opening, and having a tubular projection, a valve seat insert having a valve seat positioned in said outlet, a valve member, means for moving the valve member toward and away from the valve seat to control flow from the valve, means for releasably securing the valve seat insert to the bonnet tubular projection.

Abstract: A multi stage valve(1) having a valve member actuating mechanism located on the wide side of the valve member;(2) having a valve member and seat equipped with plural steps of increasing diameter in an upstream direction;(3) wherein the steps are configured so that a straight line can extend between opposed steps in all open positions of the valve;(4) wherein the steps are configured so that the flow passage varies in width, being narrowest at the zones of opposed steps;(5) wherein the movement of the valve member is of a magnitude equal to the width of plural steps;(6) having a movable assembly which includes the valve member and its actuating mechanism adapted for ready reception by valve bodies of various configurations;(7) having an arrangement for balancing the pressure across the valve member when it is closed;(8) having an arrangement for exteriorly showing the exact position of the valve member at all times;(9) having other features as recited herein.

Abstract: A hydraulic choking device for use in controlling fluid flow from an oil or gas well comprising choke body assembly and a choke actuator assembly having a choke actuator assembly with improved sealing means and choke plug construction, as well as a unique choke actuator drive means.

Abstract: A flow control valve installation having blind holes in internal surfaces. The holes are slanted in the downstream direction and tuned to null one or more frequencies in the noise spectrum for the valve by the selection of proper depths for the holes.

Abstract: A precision valve assembly for controlling flow of fluids to a patient having a valve element mounted on a diaphragm. At least one ball positioned in a spiral track, when moved toward the center by relative rotation of the spiral track and an opposed longitudinal track, brings a valve and valve seat together to restrict fluid flow therethrough.

Abstract: The present invention is directed to an apparatus for producing a reaction mixture from at least two fluid components comprising: (A) a storage container for each component; (B) feed pipes leading from each storage container via metering pumps to injection nozzles; (C) return pipes leading from each injection nozzle to the storage containers; (D) the injection nozzles opening into the mixing chamber of a mixhead, the mixhead having an outlet opening downstream of the injection nozzles, each injection nozzle comprising (i) a housing, (ii) a bore arranged in the housing, the bore connected to a feed pipe and a return pipe, (iii) a nozzle needle within the bore, the nozzle needle being provided with (a) an annular groove for connecting the feed pipe and the return pipe, (b) a sealing surface, and (c) a needle spindle, (iv) a sealing surface in the housing, the sealing surface adapted to contact the sealing surface of the nozzle needle, and (v) a central nozzle bore located in the sealing surface (vi) wherein the

Abstract: A streamlined control valve with integral seating means having a flow characteristic determining contour and being part of a gradually expanding flow path formed between said contour and a movable central valve plug with a streamlined contour facing an orifice and being designed to have an abrupt area change producing configuration on its discharge side.

Abstract: A pressure regulator system for providing controlled reduction of fluid pressure from a relatively high pressure fluid source to a relatively low regulated fluid pressure output. The pressure regulator system includes a pressure reduction regulator designed for stable flow under transonic conditions, and an improved solenoid valve assembly for switching the reduction regulator to an operational condition.

Abstract: An electrohydraulic pressure-regulating valve has a valve housing formed with a chamber and with an intake passage and an outlet passage opening at spaced-apart locations into the chamber, a valve member in the chamber between these locations and formed with a bore through which fluid can flow between the locations, this bore forming adjacent the outlet passage with a valve seat, a valve body in the chamber engageable with the valve seat to block flow through the bore, and means for urging the body against the seat. The valve has a laminar flow throttle in the bore between the seat and the intake passage. With this system substantially greater noise and vibration reduction is achieved in the range about 400 Herz than has been hitherto possible. Since the throttle is constituted as a laminar-flow throttle and is positioned immediately upstream of the valve body and valve seat, it only makes a nominal pressure drop, so that it does not interfere with operation of the valve.

Abstract: A novel variable proportioning valve for balanced pressure proportioning systems and variable liquid proportioning system incorporating such a valve. The valve is adjustably operable in a system to proportion or meter two liquids, for example, at constant pre-selected percentages with a resultant substantially constant or fixed ratio of the liquids even under varying flow conditions. The principles can be used with different and additional fluids. The variable proportioning valve incorporates in the body thereof a flow control plug coacting with an outlet port to control net outlet flow, and the plug is capable of having such configurations and sizes whereby relative motion between the valve plug and the port can provide a wide range of flow outputs of different specific characteristics. The valve has a construction permitting ease of disassembly for valve plug removal and replacement for purposes of repair, or for altering the operating characteristics of the valve, and therefore, that of the system.

Abstract: A thermally responsive valve (10) for valving adjacent first (21) and second (22) fluid ports is disclosed which prevents harmful fuel vapors from adversely affecting the valve power element (12). An elongated valve member (82) is movably contained within a housing fluid chamber (18) and spring-biased toward a closed position whereupon a first seal ring (90) located around the valve member engages with a valve seating surface (70) located intermediate the two fluid ports. When predetermined temperatures are encountered, a thermally responsive power element (12) connected to the lower end of the valve housing overcomes the biasing force of the spring (106) and moves the valve member to an open position in which the valve surface is spaced from the valve seat, thereby permitting fluid communication between the two ports. A lower portion (104) of the valve member extends beyond the fluid chamber and abuts with an output rod (60) of the power element.

Abstract: A flow regulating assembly and components are provided for a catheter system. The assembly provides a regulated flow of medical fluid with an intermittent operator-controlled large-volume flushing flow. The assembly includes a flow-occluding piston reciprocal within a housing to move from the regulated flow position to a position completely out of the path of fluid flow from the inlet to the outlet. Actuation of the piston is from the exterior of the housing, and adjustment of the regulated flow volume is also effected from the housing exterior. The assembly components may be sterilized and fitted together in a clean room without welding or gluing being necessary.

Abstract: A streamlined coal slurry letdown valve is featured which has a two-piece throat comprised of a seat and seat retainer. The two-piece design allows for easy assembly and disassembly of the valve. A novel cage holds the two-piece throat together during the high pressure letdown. The coal slurry letdown valve has long operating life as a result of its streamlined and erosion-resistance surfaces.

Abstract: A fluid valve controls the delivery of fluid through a passageway by employing a novel valve construction in which a channel within the passageway is adjusted both in size and configuration. A resilient, flexible valve element defines the channel, and the valve element may be adjustably and incrementally compressed to obtain a gradual restriction in the passageway. By adjusting the size of the channel the rate of fluid flow may be controlled. The fluid valve may be used, for example, to control the amount of dampening fluid supplied to the ink roll or offset plate on the plate cylinder of an offset printing press, and will find application in any fluid delivery system where precise control of fluid flow is crucial.

Abstract: Ram bodies mounted in transverse bores of a blowout preventer body with a longitudinal bore therethrough are operable by operating means extending through closures on one end of the transverse bores to move the rams to close off fluid communication through the longitudinal bore in the body and to retract the rams from the longitudinal bore. Removable seal means are provided on each ram body to seal with the transverse bore in which each ram body is mounted. Removable seal means extend diametrically across the front of each ram for sealingly engaging an elongate member in the longitudinal bore when the rams are closed. The removable seal means is retained in position by non-torquing means during use but may be readily replaced when necessary. Self energizing seal means on the ram body sealingly engage the transverse bores.

Abstract: A visbreaker, letdown valve is featured which maintains a smooth flow of furnace effluent. Liquid passing through the throat of the valve is throttled, and a portion is caused to flash to vapor. The valve is designed to allow for subsonic flow of the vapor under all process conditions. A quenching fluid is also added to the liquid passing through the throat in order to cool the liquid.

Abstract: Mud choke apparatus is disclosed, and the preferred embodiment has the form of a hollow, tubular body receiving a mud flow introduced from a lateral port, the flow being directed through an axial passage and past a valve seat. The valve seat is a replaceable, hardened metal liner and is formed with a gradual taper so that the mud flows from the large end through the tapered, smaller end. Thereafter, it flows out of the body through an axial opening. The flow of mud is throttled by a tapered, hardened plug serving as a valve element which is received into the valve seat. A hydraulic cylinder and piston with a connecting rod move the plug. The plug has a surrounding, perpendicular shoulder which seals and seats against a shoulder on the insert to fully close the throttling valve apparatus. Flow is choked by inserting the tapered plug with controlled clearance into the tapered valve seat.

Abstract: The pressure reducing element includes an elongated body having an axially-extending, cylindrical bore including three stepped portions of increasing diameter. Pressure is regulated by a stepped cylindrical valve rod having an outer end located exteriorly of the body and a pressure regulating portion normally located inside the bore and including two pressuring regulation sections of increasing diameter. The valve rod is moved axially within the bore to adjust the outlet pressure by rotating a handle on the outer end of a spindle which is connected to the valve rod and threaded into a collar carried by a fixture mounted on the body for relative axial movement. The valve rod is urged toward an adjusted position by a compression spring encircling the exterior of the body with one end restrained against axial movement relative to the body and the other end bearing against a spring retainer carried by the fixture.

Abstract: A float operated valve for controlling the rate of flow of water from a pipe carrying water under pressure, to a vessel, comprises a pipe having an end opening of selected diameter and a flange of larger diameter surrounding the pipe. A flexible diaphragm is attached over the flange having a central closure pad adapted to cut off water flow when pressed against the pipe. A small orifice is drilled through the diaphragm so that when the flow is shut off, water can still flow through the orifice to the second side of the diaphragm. A second short pipe having a similar flange is bolted against the diaphragm to the first flange, to provide a water tight seal. There is a second small orifice in the second end of the second pipe, and a float mechanism is provided with a closure tip to close the second orifice when the water level is at a selected value. The closure tip provided can vary the size of the second orifice so that as soon as it is opened, the orifice size is a minimum.

Abstract: An erosion resistant control valve or adjustable choke has a body with a side inlet, an end outlet and a conical valve seat in alignment with the outlet. Downstream from the valve seat are a converging passage having a smaller taper than the valve seat, a cylindrical passage and a diverging passage. A stem aligned with the seat assembly includes a plug having a tapered seal surface near its upstream end for engaging the valve seat and a converging control surface downstream therefrom with the same taper as the converging passage. The smaller end of the control surface is in the cylindrical passage when the valve is closed and in the converging passage is fully open for localizing erosion downstream from the valve seat. A bleed passage relieves pressure from within the valve before the valve bonnet can be removed. The valve can be locked in a selected control setting by a split ring engaging the stem.