Valtek Rotary Actuators - Apollokorea
Valtek Rotary ActuatorsSpring CylinderValtek Rotary Actuators1
Valtek Rotary ActuatorsSpring Cylinder ActuatorsHigh interchangeabilityreduces spare partrequirementsCompact, lightweight design foreasy handling, limited spaceRocking pistonprovides directconnection to shaftActuator spring forfail-safe operationSliding sealassembly forreliable long lifeoperationAdjustable stroke stopsprevent excessive rotationand reduce excessivetorque on shaftSplined lever/shaft forzero lost motionFigure 1: Spring Cylinder Rotary Actuator FeaturesThe Valtek spring cylinder rotary actuator combineshigh torque and pneumatic stiffness with excellent throttling capabilities. These characteristics are designedinto a lightweight, rugged and compact assembly, making the Valtek rotary actuator the foremost choice forquarter turn applications. The Valtek rotary actuator isdesigned to operate the Valdisk high performance butterfly valve, the ShearStream V-notch ball valve, orother applications requiring precise rotary motion. Valtek2pneumatic and electro-pneumatic positioners are available for throttling applications.The actuator, cylinder and Valtek positioner are designed for supply pressures up to 150 psi*, making veryhigh torques attainable. The actuator uses a rockingpiston for direct conversion of linear motion to rotarymotion. The rocking piston assembly combined with asplined shaft and lever eliminates lost motion.(*See Tables I and II for limitations on certain sizes.)
Valtek Rotary ActuatorsFeatures and AdvantagesImportant features and advantages of the Valtek rotary spring cylinder actuator include:FeaturesAccepts up to 150 psiair supplyAdvantages Achieves higher torques Obtains stiff piston positioning Permits higher P limits on valveRocking piston Provides direct connection to shaft Assures zero lost motion between actuator and valve Utilizes fewer partsSplined shaft and lever Allows zero lost motionCompact, lightweight, rugged Permits easy maintenance Installs in limited space applications Easily meets seismic requirementsLow friction bearings Provide millions of cycles with minimal wear Combined with direct linkage, provides very low hysteresisField reversible Requires no extra parts Permits fast, easy field reversing Requires no change of spring actionFail-safe spring Moves actuator to failure position without pressure assistanceAir-purged, fully enclosedtransfer case Prevents corrosion of linkage Ensures safe operation Contains external position indicator Allows four mounting positions without retubing, changing oradding partsStroke stops Allow both ends of stroke to be adjustedThe Valtek rotary spring cylinder actuator also capitalizes on established features of other Valtek actuators:Interchangeability Minimizes requirements for stocking spare parts Reduces inventory costs Uses identical parts in differing rotary actuator sizes Utilizes many Valtek linear actuator partsSpool-type four-wayPositioner Provides high-performance modulating positioner control Ensures ease of calibration and maintenance due to fewer partsValtek’s rotary spring cylinder actuator features high torques, positioning stiffness and easy maintenance to producea high-performance rotary actuator that excels in maintenance-free throttling and on/off control applications.3
Valtek Rotary ActuatorsStiffnessFor a 25 square-inch cylinder actuator (typical for a 2-inchvalve) with a supply air pressure of 100 psi, the spring ratewould be nearly 10,000 pounds per inch near the seat. Asthe volume under the piston becomes smaller, the stiffness factor becomes larger in a Valtek spring cylinderrotary actuator. The result of the higher actuator stiffnessin cylinder actuators is that rotary valves can be operatedin the flow-to-close orientation without position fluctuations caused by dynamic forces (flow fluctuations).The spring rate for a diaphragm actuator remains thesame, regardless of diaphragm position. The equivalentdiaphragm actuator (46 square-inch) on the same valvewith a 3-15 psi signal has a spring rate of less than 1000pounds per inch. When a rotary valve with a diaphragmactuator is operated near its closed position, suddenchanges in dynamic force can cause valve to slam shut.In contrast, the stiffness of Valtek spring cylinder rotaryactuators actually increases as the closing member approaches the seating surface. Thus Valtek rotary actuators and rotary valves may be operated with the valve shaftupstream or downstream.Figure 2: Actuator at Mid-strokeSee Valtek’s Sizing & Secltion Manual, Section 16, RotaryActuator Sizing, for more information.Control valves generally are used by the process control industry to regulate constantly fluctuating flows. Asthe dynamic forces of a flow increase or decrease, thecontrol valve must remain in the same position asdictated by the controller. To do this, the valve isdependent upon the actuator stiffness to minimizethese position fluctuations.Actuator stiffness is defined as the ability of the actuatorto withstand suddenly changing dynamic fluid forcesacting on the valve trim.Since supply air pressure is delivered to both sides ofthe piston in the cylinder, the stiffness of the Valtekspring cylinder rotary actuator is significantly greaterthan that of a diaphragm actuator.The stiffness (spring rate) is equal to the expression:kPA2vWhere: K spring ratek ratio of specific heatP supply pressureA2 piston area (in2)v cylinder volume under pistonK 4Figure 3: Actuator withHigh Stiffness / Spring Rate
Valtek Rotary ActuatorsPerformanceTorque Producing CapabilityFrequency ResponseValtek spring cylinder rotary actuators produce substantially higher torque than comparable diaphragmactuators because the cylinder operates with supplypressures up to 150 psi. Throttling diaphragm actuators are limited to 40-60 psi, thus decreasing theirtorque-producing capability. Higher actuator air supply,coupled with high-pressure air on both sides of theactuator piston, provide exceptional stiffness for precise throttling control. Valtek rotary actuator stiffness issufficient to control high pressure drops and to permitthe valve to throttle near the seat.The frequency response of Valtek cylinder actuators isextremely high – generally an order of magnitude betterthan comparable diaphragm actuator units. Suchresponse is achieved through a double-acting configuration that uses pressure on both sides of the piston.Size 25 Actuator, 9 psi 2 psi03Relative Response dB6Cam Characterizable OperationValtek's standard Beta positioner, is provided with areversible cam that characterizes Valdisk's CV to eithermodified equal percent or linear performance. Thesame cam enhances the ShearStream control valve'sinherent equal percent characteristic.A second rotary cam is also available. This optionalcam gives ShearStream valves a linear relationship ofrotation with respect to the controller signal. It isreversible for use in air-to-close or air-to-open, failopen applications and is also linear in this mode.Degrees9120Phase Angle3060901201501800.010.040.10.41.0410Frequency – HertzFigure 4: Frequency ResponseSpeed and SensitivityHysteresis and RepeatabilityHigh air-handling capacity of the positioner, combinedwith relatively low cylinder volumes, produces faststroking speeds. High operating speed is achieved withvirtually no overshoot when approaching the final discor ball position. At the same time, static sensitivity of theunit is excellent. For example, as little as 0.017 psi isrequired to rotate the shaft 0.01 degrees (the minimumdetectable movement in the tests conducted) on a size25 actuator. A signal change of only 0.02 psi is requiredto reverse the shaft motion.An important characteristic of any actuator is its abilityto respond to signal changes from the controller and togive uniform response unaffected by decreasing orincreasing pressures. Tests have shown that both thehysteresis and repeatability of the spring cylinder rotaryactuator, with Beta positioner are less than 0.7 percentof full scale. (See Table VII: Beta Positioner Performance on page 10.)Size 25 Actuator, Signal 4.2 to 13.8 psigInput Signal13.8 psigSignalniolveitosPVa4.2 psig00.00.50.721.00Time (seconds)Figure 5: Step Test5
Valtek Rotary ActuatorsTorque OutputTable I: Net Torque Output of Actuators at Various Supply Pressures, (in.-lb.)ActuatorSizeSupplyPressureDegrees from Fail Position on Air Supply LossSTD 25 withSTD Spring1501401201008060Spring 1928146310013919025322339196215771191806349STD 25 withHD Spring1501401201008060Spring 21167781396758STD 50 withSTD Spring1501401201008060Spring 3STD 50 withHD Spring1501401201008060Spring STD 100 withSTD Spring1501401201008060Spring 1589013135220352037817119138081048571672775STD 100 withDual Springs1501401201008060Spring 71648314832115638245492716118316STD 200 withSTD Spring80*706050Spring 332567020697167243135234162020616926136462775STD 200 withDual Springs80*706050Spring 393184201444510478940717887146501137080838316NOTE: For air-to-open/fail-closed actuators the 0 degree position shown above corresponds to the disc or ball being seated.For air-to-close/fail-open actuators the 90 degree position shown above corresponds to the disc or ball being seated.* Size 200 actuator limited to 80 psi air supply pressure6
Valtek Rotary ActuatorsSpecificationsTable II: Rotary Actuator Area(sq.in.)ShippingWeight**251.880.94150STDHD (Cap)18022223.7623.0730503.251.63150STDHD 2265* Valve in closed position** Estimated, including Beta PositionerTable III: Actuator g pressureTemperature rangeCylinder with positive springaction25, 50, 100 and 200 sq. in.Single (std.), heavy-duty,dualField reversible: Air-to-open,Air-to-closeUp to 150 psi**-40OF to 350OF** Ambient temperatures greater than 180OF require Viton O-rings.Ambient temperatures below -40OF require fluorosilicone Orings. (Viton is a registered trademark of E.I. DuPont.)** See Table II for limitations on certain actuators.Table IV:Stroking Speeds with Positioner*Time in Secondsfor 90O RotationActuatorSize1/4" Tubing(standard)3ActuatorStroke/8" Tubing(optional)(inches)25 (std)1.01.01.8850 (std)3.53.53.25100 (std)9.59.04.00* Beta positioner stroking valve to fail position. Consult factoryfor speeds faster than those shown above.Table V: Materials of ConstructionYokeDuctile ironTransfer caseAnodized aluminumSplined lever arm Ductile ironStem416 stainless steelBearingsFilament wound fiberglass withTeflon linerSliding sealDelrin 100, aluminumRetaining ringCadmium plated steelPistonAnodized aluminumCylinderAnodized aluminumO-ringBuna N (std.)Actuator springCoated steel (rust proof)Spring buttonPainted steel or cadmium platedOrdering InformationWhen ordering individual rotary actuators, the followinginformation must be provided:1. Operating conditions, throttling or on/off.2. Maximum air supply pressure.3. Valve rotation in degrees.4. Actuator torque required at both ends of rotation.5. Positioner and input signal range, if needed.6. Stroking time requirements, if critical.7
Valtek Rotary ActuatorsBeta PositionersEasy calibrationIndependentzero andspanCorrosion-resistantcover and baseSimple signalconversion withinterchangeable modulesTwo-sidedcam foreasy fieldreversibilitySplit rangescan be easilyadjustedFigure 6: Beta Positioner FeaturesFlowserve primarily utilizes Beta positioners. The ValtekBeta positioner is available with either a pneumaticmodule for air control signals, or an electro-pneumatic(I/P) module for milliamp electrical control signals. Betapositioners are single or double-acting, force-balancedinstruments that provide fast, sensitive and accuratepositioning of cylinder and diaphragm actuators. Thesepositioners are compact, field reversible, designed forhigh performance, and ruggedly built for reliability.Features P/P or I/P Signal Convertible – Field conversionfrom one control signal to another is easily accomplished by replacing one module with the other. Corrosion Resistant – Cover and base assemblyare epoxy powder painted and continuously purgedfrom the inside with instrument air. Internal workingparts are constructed from 300 series stainless steel,anodized aluminum or Buna-N. Shock and Vibration Resistant – Beta positionersare designed with a high natural frequency coupledwith pneumatic damping. It is unaffected by vibration,accel-eration up to 2 G’s, and frequencies to 500 Hz. For Single or Double-acting Actuators – Usablewith either single or double-acting actuators (bothlinear and rotary) makes the Beta positioner versatile. Standard Mounting – Beta positioners use the samestandard mounting as Valtek System 80 positioners.By changing the cams and follower arms, the samepositioner can be used on both linear and rotaryactuators. This results in fewer required spare parts. Easily Field Reversed – Action can be reversed inthe field by simply turning the cam over, reversing theanti-backlash spring and changing the output tubing.8 Insensitive to Mounting Position – Positioners canbe mounted in any orientation. Simple Calibration – Calibration is easy due to minimalinteraction between zero and span. Positioner adjustments are totally enclosed for protection and to discourage tampering. Split-Range Service – Standard signal ranges are 4 20 mA for the electro-pneumatic (I/P) module and 3 - 15psi for the pneumatic (P/P) model. Optional ranges are10 - 50 mA and 6 - 30 psi, respectively. All models canbe calibrated for a 2 or 3-way split range. Simplified Maintenance – Positioners’ simplicity, modular design and few parts, make maintenance easy. No Regulator Required – Beta positioners are designed to withstand 150 psi at all ports, and are insensitive to supply pressure fluctuations. Low Air Consumption – Steady state air consumption is.25 SCFM @ 60 psi supply (I/P module max. .31 SCFM ). Changeable Flow Charactaristics – Easily changedcam provides characterized flow feedback. High Air Flow Gain Model – Standard on 200 squareinch actuators and above, optional on others. Output Gauge Helps Monitor Unit – Indicates transducer output to the positioner, permitting easy verification of transducer and positioner calibration. Minimum Pressure Cutoff – When initiated, causesthe IP 2000 module output to decrease to near zero whenthe input signal falls below a user-determined point. Replaceable Coalescing Filter (IP 2000) – Removesparticles that could clog transducer. Large orifice/airpassages provide additional protection against clogging. Self-controlling Internal Regulator (IP 2000) – Reducespressure to 22 psi, eliminating need for external regulator.
Valtek Rotary ActuatorsBeta Positioner OperationOutput 24-20 mASignalFlapperCylinderCoilPiston –Range Adjustment ScrewOutput 1NozzleRange Adjustment Lock ScrewPressureSensorZero AdjustmentRegulatorZeroAdjustmentLockKnobFilterI/P MODULEFeedback SpringMODULETo SignalFollower ArmBalanceBeamSignal3-15 psiSignalActuatorLever ArmC3-15psiInstrument Signal CapsulePNEUMATIC MODULEPilot Valve BodyPilot Valve SpoolFigure 7: Positioner Schematic for Air-to-Open (Retract)The Beta positioner is a force-balanced instrument. Figure 4 shows a Beta positioner, with either a pneumaticor electro-pneumatic module, installed on a double-acting actuator for air-to-open action. Positioning is basedon a balance of two forces; one proportional to the instrument signal and the other proportional to the stem position.With the IP 2000 model, the current signal is first converted to a 3-15 psi air signal. For the pneumatic model,the 3-15 psi signal is passed directly into the positioner.The transducer receives an electric input signal andconverts it to an output proportional to the input. Thesupply pressure is filtered and regulated in the transducer by a filter element and an internal regulator.The output of the transducer is controlled by a feedbackloop consisting of a pressure sensor, electromagneticpressure modulator and circuit board. The pressuremodulator consists of a stiff flapper that is attracted bythe electromagnet to a nozzle. The nozzle-flapperspacing determines the transducer output.Based on the difference between the input and the outputmeasured by the pressure sensor, the circuit board sendsa current to the pressure modulator that adjusts the nozzleflapper spacing to provide the correct output.The detailed sequence of positioner operations are asfollows: An increase in the instrument signal forces theinstrument signal capsule and balance beam downward.This motion of the balance beam also pulls the pilot valvespool downward from its equilibrium position. This opensthe pilot valve ports, supplying air to port 1 and exhaustingair from port 2. This causes the actuator piston upward.This upward motion of the piston is transmitted back to thepositioner through the feedback linkage and cam resultingin the spring being stretched proportionally to the valve position. The piston continues to stroke upward until theforce in the feedback spring increases sufficiently tocounter the force generated by the instrument signal capsule. At this point, the balance beam and spool begin toreturn to equilibrium position. As the valve spool ports startto close, the air flow rate to the actuator is decreased.After the piston has reached the required position, thefeedback spring tension force will equal the force generated in the instrument signal capsule. The balancebeam and instrument signal capsule will remain in theirequilibrium positions with no air flowing to the actuatoruntil a change in the instrument signal is made.A decrease in the instrument signal
Valtek Rotary Actuators Performance Torque Producing Capability Valtek spring cylinder rotary actuators produce sub-stantially higher torque than comparable diaphragm actuators because the cylinder operates with supply pressures up to 150 psi. Throttling diaphragm actua-tors are limited to 40-60 psi, thus decreasing their torque-producing .
Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611 55-1 Valtek VL-UHC Spring Cylinder Linear Actuators GENERAL INFORMATION The following instructions are designed to assist in installing, troubleshooting and servicing Valtek VL-UHC spring cylinder actuators. Product users and mainte-nance personnel should thoroughly review .
The Valtek Mark One is the industry choice for a simple, reliable, tough globe valve. The Valtek Mark One TM globe control valve offers superior performance in liquid and gaseous services, while also permitting easy, fast and inexpensive maintenance. Unlike diaphragm-operated control valves, the spring-cylinder actuated Mark One provides .
Valtek XL Series Positioner Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611 Figure 2: XL Series Positioner Mounted on Valtek Linear Actuator Figure 3: XL Series Positioner Mounted on Fisher 657 Actuator Calibration is easy using the XL positioner due to minimal interaction between zero and span. Also, the
Piston / Cylinder Cylinder actuator should be applied when the process requires the following: 1. Double acting 2. Field reversible 3. Light weight, compact design 4. High stiffness (for throttling near seat) 5. Actuation speed 1 sec. 6. High supply pressure 50 to 150 psi 7. Interchangeability with Valtek rotary products (Vald-
valve controllers. Valtek control products are also known for handling the most severe services: cryogenic, superheated steam, volatile and corrosive fluids, erosion, high pressure drops, vibration, cavitation, flashing, and high noise levels. Valtek valves are equipped with spring cylinder actuators that provide the thrust and speed necessary .
DeZURIK rotary diaphragm actuators are available for use on rotary control valves including: V-Port Ball Valves BHP High Performance Butterfly Valves RCV Rotary Control Valves The common ISO-5211/1 bolt pattern allows the actuators to be easily interchanged on these rotary control valves.
Valtek's first choice of bellows seals for installation in Valtek Mark One valves. The Guardian can handle temperatures between -320 and 650 degrees Fahrenheit and pressures to 400 psi. The typical cycle life for Valtek's basic design when throttling between 25 and 75 percent open is 200,000 cycles. Figure 3 shows the
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