Showing posts with label control valve. Show all posts
Showing posts with label control valve. Show all posts

Control Valve Glossary

Reprinted with permission of Cashco.
Linear Control Valve Design
Click for larger view.
Actuator: An actuator is a pneumatic hydraulic, or electrically powered device which supplies force and motion to open or close a valve.

Airset: A regulator which is used to control the supply pressure to the valve actuator and its auxiliaries.

Angle valve: A valve design in which one port is collinear with the valve stem or actuator, and the other port is at a right angle to the valve stem.

Anti-cavitation trim: See “trim, anti-cavitation”. Anti-noise trim: See “trim, anti-noise”.

Bellows stem seal: A thin wall, convoluted, flexible component that makes a seal between the stem and bonnet or body and allows stem motion while maintaining a hermetic seal.

Benchset: The calibration of the actuator spring range of a control valve, to account for the in service process forces.

Body: The main pressure boundary of the valve that also provides the pipe connecting ends, the fluid flow passageway, and supports the seating surfaces and the valve closure member.

Bonnet: The portion of the valve that contains the packing box and stem seal and may guide the stem. It may also provide the principal opening to the body cavity for assembly of internal parts or be an integral part of the valve body. It may also provide for the attachment of the actuator to the valve body. Typical bonnets are bolted, threaded, welded to, pressure-sealed, or integral with the body.

Butterfly valve: A valve with a circular body and a rotary motion disk closure member, pivotally supported by its shaft.

Rotary Control Valve Design
Click for larger view.
Cage: A part of a valve trim that surrounds the closure member and may provide flowcharacterization and/ or a seating surface. It may also provide stability, guiding, balance, and alignment, and facilitate assembly of other parts of the valve trim.

Capacity: The rate of flow through a valve under stated conditions.

Cavitation: A two-stage phenomenon of liquid flow. The first stage is the formation of vapor bubbles
within liquid system due to static pressure of fluid at vena contracta falling below the fluid vapor pressure; the second stage is the collapse or implosion of these cavities back into an all-liquid state as the fluid decelerates and static pressure is recovered.

Characteristic, flow: An indefinite term, see “characteristic, inherent flow” and “characteristic, installed flow.”

Characteristic, equal percentage: An inherent flow characteristic which, for equal increments of rated travel, will ideally give equal percentage changes of the existing flow coefficient (cv).

Characteristic, inherent: The relationship between the flow coefficient (cv) and the closure member travel as it is moved from the closed position to rated travel with constant pressure drop across the valve.

Characteristic, linear: An inherent flow characteristic that can be represented by a straight line on a rectangular plot of flow coefficient (cv) versus rated travel. Therefore, equal increments of travel provide equal increments of flow coefficient (cv).

Characteristic, quick opening: An inherent flow characteristic in which a maximum flow coefficient is achieved with minimal closure member travel.

Characterized cam: A component in a valve positioner used to relate the closure member position to the control signal.

Characterized trim: Control valve trim that provides predefined flow characteristics.

Closure member: The movable part of the valve that is positioned in the flow path to modify the rate of flow through the valve.

Closure member configurations (plug):
  • Characterized: Closure member with contoured surface, such as the “vee plug,” to provide various flow characteristics.
  • Cylindrical: A cylindrical closure member with a flow passage through it (or a partial cylinder).
  • Eccentric: Closure member face is not concentric with the stem centerline and moves into seat when closing.
  • Eccentric spherical disk: Disk is spherical segment, not concentric with the disk stem.
  • Linear: A closure member that moves in a line perpendicular to the seating plane.
  • Rotary: A closure member which is rotated into or away from a seat to modulate flow.
Coefficient, flow: A constant (cv) related to the geometry of a valve, for a given valve travel, that can be used to predict flow rate.

Control valve: A valve which controls the flow rate or flow direction in a fluid system. The final control element, through which a fluid passes, that adjusts the flow passage as directed by a signal from a cont- roller to modify the flow rate.

Dual sealing valve: A valve that uses a resilient seating material for the primary seal and a metal-to-metal seat for a secondary seal.

End connection: The configuration provided to make a joint with the pipe.
  • End connections, flanged: Valve body with end connections incorporating flanges that mate with corresponding flanges on the piping.
  • End connections, split clamp: Valve end connections of various proprietary designs using split clamps to apply gasket or mating surface loading.
  • End connections, threaded: Valve end connections incorporating threads, either male or female.
  • End connections, welded: Valve end connections which have been prepared for welding to the line pipe or other fittings. May be butt weld (bw), or socket weld (sw).
Erosion resistant trim: Valve trim, that has been designed with special surface materials or geometry to resist the erosive effects of the controlled fluid flow.

Extension bonnet: A bonnet with a packing box that is extended above the bonnet joint of the valve body so as to maintain the temperature of the packing above or below the temperature of the process fluid. The length of the extension bonnet is dependent upon the difference between the fluid temperature and the packing design temperature limit as well as upon the valve body design.

Face to face dimension: The dimension from the face of the inlet opening to the face of the outlet opening of a valve or fitting.

Facing, flange: The finish on the end connection that mates with gasket surfaces.

Failure mode: The position to which the valve closure member moves when the actuating energy source fails.
  • Fail-closed: A condition wherein the valve closure member moves to a closed position when the actuating energy source fails.
  • Fail-in place: A condition wherein the valve closure member stays in its last position when the actuat- ing energy source fails.
  • Fail-open: A condition wherein the valve closure member moves to an open position when the actuat- ing energy source fails.
  • Fail-safe: A characteristic of a particular valve and its actuator, which upon loss of actuating energy supply, will cause a valve closure member to fully close, fully open or remain in fixed last position. Fail-safe action may involve the use of auxiliary controls connected to the actuator.
Flangeless control valve: A valve without integral line flanges, which is installed by bolting between companion flanges, with a set of bolts, or studs, generally extending through the companion flanges.

Guides, closure component: The means by which the closure is aligned with the seat and held stable throughout its travel. The guide is held rigidly in the body, bonnet, and/or bottom plate.

Hand jack: A manual override device, using a lever, to stroke a valve or to limit its travel.

Handwheel: A mechanical manual override device, using a rotary wheel, to stroke a valve or to limit its travel.

Hard facing: A material applied to valve internals to resist fluid erosion and/or to reduce the chance of galling between moving parts, particularly at high temperatures.

Hard plating: A thin metal deposit, sometimes electroplated, used to induce surface hardening. Hard plating is many orders of magnitude thinner than hard facing.

Hysteresis: The maximum difference in output value for any single input value during a calibration cycle, excluding errors due to dead band.

Integral seat: A flow control orifice and seat that is an integral part of the body or cage.

Jacketed valves: A valve body cast with a double wall or provided with a double wall by welding material around the body so as to form a passage for a heating or cooling medium. Also refers to valves which are enclosed in split metal jackets having internal heat passageways or electric heaters. Also referred to as “steam jacketed” or “vacuum jacketed.” in a vacuum jacketed valve, a vacuum is created in the space between the body and secondary outer wall to reduce the transfer of heat by convection from the atmosphere to the internal process fluid, usually cryogenic.

Lantern ring: A rigid spacer assembled in the packing box with packing normally above and below it and designed to allow lubrication of the packing or access for a leak-off connection.

Lapping-in: A process of mating contact surfaces by grinding and/or polishing.

Leakage, class: Classifications established by ansi b16.104 to categorize seat leakage tolerances for different sizes of control valve trim.

Leakage, seat: The quantity of fluid passing through a valve when the valve is in the fully closed position with pressure differential and temperature as specified.

Leak-off gland: A packing box with packing above and below the lantern ring so as to provide a collection point for fluid leaking past the primary seal (lower packing).

Lined valve body: A valve body in which a coating or liner has been applied to internal surfaces for cor- rosion/erosion protection or for flow shut off.

Liner, slip-in: An annular shaped liner which makes a slight interference fit with the body bore and which may be readily forced into position through the body end. May be plain or reinforced. Applies to butterfly valves.

Liquid pressure recovery factor: The ratio (fl) of the valve flow coefficient (cv) based on the pressure drop at the vena contracta, to the usual valve flow coefficient (cv) which is based on the overall pressure drop across the valve in non-vaporizing liquid service. These coefficients compare with the orifice metering coefficients of discharge for vena contracta taps and pipe taps, respectively. See ansi/isa-s75.01 “control valve sizing equations.”

Lubricator isolating valve: A manually operated valve used to isolate the packing lubricator assembly from the packing box.

Lubricator packing box: A packing arrangement consisting of a lantern ring with packing rings above and below with provision to lubricate the packing.

Mechanical limit stop: A mechanical device to limit the valve stem travel.

Mounting position: The location and orientation of an actuator or auxiliary component relative to the control valve. This can apply to the control valve itself relative to the piping.

Multiple orifice: A style of valve trim where the flow passes through a multiple of orifices in parallel or in series.

Nominal size: A numerical designation of size which is common to all components in a piping system other than components designated by outside diameters or by thread size. It is a convenient round number for reference purposes and is only loosely related to manufacturing dimensions. Iso uses initials dn as an abbreviation for the term with the letters dn followed by a numerical value designating size. All equipment of the same nominal size and nominal pressure rating shall have the same mating dimensions appropriate to the type of end connections.

Packing: A sealing system consisting of deformable material contained in a packing box which usually has an adjustable compression means to obtain or maintain an effective seal.

Packing box: The chamber, in the bonnet, surrounding the stem and containing packing and other stem sealing parts.

Packing flange: A device that transfers the deforming mechanical load to the packing follower.

Packing follower: A part which transfers the deforming mechanical load to the packing from the packing flange or nut.

Packing lubricator assembly: A device for injection of lubricant/sealer into a lubricator packing box.

Pinch or clamp valve: A valve consisting of a flexible elastomeric tubular member connected to two rigid flow path ends whereby modulation and/or shut off of flow is accomplished by squeezing the flexible member into eventual tight sealing contact.

Plug: A term frequently used to refer to the closure member.

Plug valve: A rotary motion valve with a closure member that may be cylindrical or conical. Port: The flow control orifice of a control valve.

Port guiding: A valve closure member with wings or a skirt fitting into the seat ring bore.

Positioner: A position controller, which is mechanically connected to a moving part of a final control element or its actuator, and automatically adjusts its output pressure to the actuator in order to maintain a desired position that bears a predetermined relationship to the input signal. The positioner can be used to modify the action of the valve (reversing positioner), extend the stroke/controller.

Positioner, double acting: A positioner with two outputs, suited to a double acting actuator.

Positioner, single acting: A positioner with one output, suited to a spring opposed actuator.

Position switch: A position switch is a pneumatic, hydraulic or electrical device which is linked to the valve stem to detect a single, preset valve stem position.

Position transmitter: The position transmitter is a device that is mechanically connected to the valve stem or shaft and generates and transmits a pneumatic or electrical signal representing the valve position.

Post guiding: A design using guide bushing or bushings fitted into the bonnet or body to guide the plug’s post.

Pressure energized seal: A seal energized by differential pressure.

Rangeability inherent: The ratio of the largest flow coefficient (cv) to the smallest flow coefficient (cv) within which the deviation from the specified inherent flow characteristic does not exceed the stated limits.

Rated travel: The amount of movement of the valve closure member from the closed position to the rated full open position.

Seat: The area of contact between the closure component and its mating surface which establishes valve shut-off.

Seat ring: A part of the valve body assembly that provides a seating surface for the closure member and may provide part of the flow control orifice.

Shaft: The mechanical member used to support a rotary closure member.

Spring rate: The force change per unit change in length of a spring.

Stem connector: The device which connects the actuator stem to the valve stem. Stem guide: A guide bushing closely fitted to the valve stem and aligned with the seat.

Three-way valve: A valve with three end connections, used for mixing or diverting flow.

Throttling: The action of a control valve to regulate fluid flow by varying the position of the closure member. This service generates a variable pressure drop.

Transducer: A device that is actuated by power from one system and supplies power in another form to a second system.

Travel: The movement of the closure member from the closed position to an intermediate or rated full open position.

Travel indicator: A pointer and scale used to externally show the position of the closure member; typically in terms of units of opening percent of travel or degrees of rotation.

Trim: The internal components of a valve which modulate the flow of the controlled fluid.
  • Trim, anti-cavitation: A combination of control valve trim that by its geometry reduces the tendency of the controlled liquid to cavitate.
  • Trim, anti-noise: A combination of control valve trim that by its geometry reduces the noise generated by fluid flowing through the valve.
  • Trim, balanced: Control valve trim designed to minimize the net static and dynamic fluid flow forces acting on the trim.
  • Trim, reduced: Control valve trim which has a flow area smaller than the full flow area for that valve. Trim, soft seated: Valve trim with an elastomeric, plastic or other readily deformable material used
  • either in the closure component or seat ring to provide tight shutoff with minimal actuator forces.
Unbalance, dynamic: The net force/torque produced on the valve stem/shaft by fluid pressure acting on the closure member and stem/shaft at stated travel and flowing conditions.

Unbalance, static: The net force produced on the valve stem by the fluid pressure acting on the closure member and stem with the fluid at rest and with stated pressure conditions.

Valve: A device used for the control of fluid flow, consisting of a fluid retaining assembly, one or more ports between end openings and a movable closure member which opens, restricts or closes the port(s).
  • Balve, ball: A valve with a rotary motion closure member consisting of a full ball or a segmented ball.
  • Valve, diaphragm type: A valve with a flexible linear motion closure member which is moved into the
  • fluid flow passageway of the body to modify the rate of flow through the valve by the actuator.
  • Valve, floating ball: A valve with a full ball positioned within the valve that contacts either of two seat rings and is free to move toward the seat ring opposite the pressure source when in the closed position to effect tight shutoff.
  • Valve, globe: A valve with a linear motion closure member, one or more ports and a body distinguished by a globular shaped cavity around the port region.
Vena contracta: The location in a flow stream where fluid velocity is at its maximum and fluid static pressure and the cross-sectional area are at their minimum. In a control valve, the vena contracta normally occurs just downstream of the actual physical restriction.

Yoke: The structure which rigidly connects the actuator power unit to the valve.

Glossary courtesy of Cashco, Inc. For more information about Cashco products, contact Miller Energy, Inc. Call them at 800-631-5454 or visit their web site at https://millerenergy.com.

The Design Principle of Segment Disc Control Valves


Figure 1.
The central throttle device of this control valve is two discs with segmented openings which slide on one another and seal against each other (Fig. 1). The segment discs are positioned vertically in the valve housing, facing the direction of flow. A moving disc is placed upon a rotationally fixed segment disc, the geometry of which determines the throughput capacity and characteristic curve. These two discs have the same number of segments and the moving disc is rotated via a push rod which is tangentially inserted. Consequently, the cross-section surface of the free segment passage changes when a control intervention is made.

Irrespective of the pending pressure differential, the moving segment disc is pressed onto the fixed disc via a spring pack- age. This ensures that the direction of flow is variable and that the valve can be installed in any desired location. Due to the fact that there are no metal seats with ring-shaped contact surfaces, no grooves will occur which can rapidly lead to leaks in traditional steam valves. Leakage ratios amounting to < 0.001% of the Kvs value are constantly achieved with the significantly less vulnerable surface seal.

Extremely robust segment disc valve from
Schubert & Salzer for steam distribution.
Thanks to this special design, segment disc valves are one of the few valves that are able to combine control precision and a high level of tightness, even in extreme conditions and which also experience hardly any wear.

The standard segment disc valves are available in finely graduated intervals of between DN 25 and DN 300 – and go up to DN 800 where necessary – in an intermediate flange design for nominal pressures up to PN 25. They can be used for media temperatures ranging between -60°C and +220°C (higher temperatures and nominal pressures are available on request). The robust valves have a rangeability of 60:1.

For more information, contact Miller Energy, Inc. by calling 800-631-5454, or visit their web site at https://millerenergy.com.

How to Change Loss of Signal Failure Mode on the Cashco Ranger Control Valve


This video provides step-by-step instructions on how to change the Cashco Ranger (control valve) loss of signal failure mode from air to open / fail closed to air to close/ fail open, as well as remounting and recalibrating the valve positioner.

The Cashco Ranger is one of the most popular control valves on the market. It is the most versatile, adaptable, and easily maintainable valve ever produced.

The Ranger offers over 6 different trim combinations. Trim can easily be changed in less than 5 minutes without disturbing the packing, actuator, or positioner calibration. The service area is a thread-less design, which resists corrosion or collection of chemical deposits.

A selection of 3 body materials with a broad temperature range from -325°F to +750°F makes the Ranger adaptable for use in steam, heat transfer fluids, slurries, gases, liquids, and cryogenic applications. The Ranger’s unique dual seating design provides both Class VI and backup Class IV seat leakage. And the standard patented live-loaded packing system lets you check and adjust packing without the need for specialized tools or complicated procedures.

For more information about Cashco in Metro New York, New Jersey, and Eastern Pennsylvania contact:

Miller Energy, Inc.
New York Metro and Northern NJ: 800-631-5454
Eastern PA, Southern NJ, Delaware: 888-631-5454
https://www.millerenergy.com

Composite Solenoid Valves for Water Purification Systems

composite solenoid valve for water purification system use
Composite construction, along with other targeted features,
make the ASCO 212 Series a good choice for membrane water
purification systems and equipment.
Image courtesy Emerson - ASCO
Water purification systems and equipment present a unique set of fluid control challenges. Purified water is aggressive and will rapidly corrode most metallic parts. Additionally, strong chemicals are utilized in some systems for cleaning or regeneration, presenting yet another longevity challenge for the process valves needed to operate a system or equipment skid.

ASCO, an Emerson Brand, has developed a line of solenoid operated valves targeted at membrane based water purification applications. These applications include desalination skids and a broad range of ultrafiltration, and reverse osmosis equipment installations.

The Series 212 delivers substantial benefit to customers, through its basic construction, design and ease of use.

  • Compliance and certification listings with applicable current standards and codes.
  • Short lead time with quick-ship program from distributors.
  • High reliability - tested up to one million cycles.
  • Ease of connectivity, available as Turn & Lock, NPT thread, or solvent bond.
  • FasN connection system enables greatest equipment design and assembly flexibility.
  • Normally open and normally closed versions available.
More detail is provided in the datasheet included below. Share your fluid control challenges with process control specialists at Miller Energy, leveraging your own knowledge and experience with our product application expertise to develop effective solutions.



Voltage Ranging Solenoid Valve Coils are a Game Changer

industrial solenoid operated valve with voltage ranging coil
Voltage ranging coils simplify the application of solenoid valves
Image courtesy Emerson - ASCO
New power management technology is rewriting industry standards for reliability and power consumption of solenoid valve coils. The new technology solenoid valves accept both AC and DC voltage while improving performance. Available in 2-way, 3-way and 4-way, these solenoid valves are designed to handle a wide range of fluid control applications.

The enhanced valves are designed to be drop in replacements for existing valves. There is no change to functional attributes such as flow, pressure, ambient & fluid temperatures or physical attributes such as envelope size and face-to-face dimensions. If you're looking to just switch out a coil, enhanced coil kits are direct replacements for the old coil kits.

Here are the benefits to end customers:

Lower Power Consumption
  • 1.0 watt (DC version) & 1.5 watts (AC/DC versions)
  • Lowers energy cost up to 80% compared to standard solenoid valves 
RoHS 2 Compliant
  • Satisfies CE Directives 2002/95/EC and 2001/65/EU (RoHS 2) for the restriction of hazardous substances 
Supervisory Current Compatible
  • Suitable for systems employing supervisory currents not exceeding the following drop-out currents: 20mA (12-24V DC), 15mA (24-120V AC/DC) and 7mA (100-240V AC/DC) 
  • Also suitable with devices having leakage currents not exceeding the drop-out currents noted above. 
Broad Voltage Ranges Reduce Inventory
  • Available in 24-120V AC/DC, 100-240V AC/DC & 12-24V DC 
  • Covers hundreds of global voltage requirements
  • Simplifies product selection and reduces complexity
  • Lowers inventory cost by eliminating need to stock both AC & DC products
  • Includes 125VDC battery (AC/DC versions) & 24VDC battery (DC version) 
DC Performance Increased Up to 500% To Match AC Ratings
  • Transition from AC to DC without sacrificing performance
  • Eliminates the need for separate AC & DC output cards
  • Simplifies control schemes
Integrated Surge Suppression
  • Prolongs the life of the coil by suppressing external voltage spikes
  • Lowers system cost by eliminating the need for additional surge protection
Fit For Use In Rugged and Demanding Environments
  • Wide ambient temperature range for hot and cold environments
  • Enclosure Types 1 through 4X for indoor and outdoor applications 
  • Optional Class 1, Division 2 coils available for hazardous locations
No AC Hum
  • Ideal for applications requiring quiet operation
More information and application assistance is available from product specialists. Leverage your own knowledge and experience with their product application expertise to develop effective solutions.

Electronic to Pneumatic Converter

illustration of setup for current to pneumatic converter
Component schematic using electronic controller and pneumatic
control valve
Image courtesy of Yokogawa
A straight forward device, the current to pneumatic converter produces a pneumatic output signal that is proportional to an electrical control level input signal of 4 to 20 mA or 10 to 50 mA. This provides a useful interface between electronic controllers and pneumatically operated valves, air cylinders, or other air operated control elements.

Pneumatic signals are regularly used throughout many installations as matter of safety, legacy, or because a pneumatic signal can provide motive power to an operating device such as a valve positioner. Electrical control signals can be transmitted long distances across wires to deliver control signals to operating elements. The current to pneumatic converter provides a bridge between the two systems and allows the most beneficial aspects of each to be brought to bear on process operation.

Converters are available in standard variants that accommodate a number of hazardous location designations, as well as several output pressure ranges and calibrations. Share your process control connectivity challenges with application specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.


Industrial Control Valves

cutaway view of industrial control valve plug valve
Cutaway view of industrial control valve
Courtesy Cashco
Control valves are at the heart of almost every fluid based industrial control process. Understanding their basic operation and function is essential for the process engineer, operator, or other stakeholder. A previous blog provided a good information source for those wishing to learn about control valves or review and hone their technical knowledge. The applications for which control valves are used seem uncountable in their variety, but common operating traits of control valves enable their use in every one.

Cashco, globally recognized manufacturer of industrial control products including control valves, regulators, controllers, pressure/vacuum relief vents, and flame and detonation arrestors, will be exhibiting at Interphex in Booth 3464 on March 21 through March 23 at the Jacob Javits Center in New York City. Knowledgeable personnel will be on hand to discuss your industrial control applications and challenges. If your plans include attendance at Interphex this year, take advantage of the opportunity to speak face to face with representatives of an industry leader.