470 Series Piston Actuators

Transcription

1 January 000 Bulletin 61.: Series Piston Actuators The 470 Series pneumatic piston actuators (figure 1) are used in either throttling or on-off applications with control valves having 90.5 mm (3-9/16 inch) through 17 mm (5 inch) yoke bosses. They require pneumatic pressure loading from double-acting positioners, including the 3570 Series, or from on-off loading and unloading devices. TYPE 3570 POSITIONER Features Actuator Versatility Actuators with or without positioners, snubbers, handwheels, and spring return options are available in an assortment of sizes, stroking speeds, thrusts, and travels to handle most control requirements. 470 SERIES ACTUATOR High Thrust Maximum usable thrusts of up to 111,000 Newtons (5,000 pounds) with the size 130 steel yoke actuator provide the force necessary to overcome high valve unbalance. Wide Range Supply Pressure Capability The cylinder (and 3570 Series positioner, if used) can operate with supply pressures as low as.4 bar (35 psig) or as high as 10.4 bar (150 psig). Long Stroke Actuators have maximum rated travels of up to 06 mm (8-1/8 inches) Series Positioner Versatility 3570 Series positioner action is easily reversed in the field with no additional parts (figure ). Positioner sensitivity, travel span, and travel starting point are factory set and need to be reset only if operating conditions have changed or if the positioner has been reversed. W5566* / IL Figure Series Actuator with Type 3570 Positioner D100090X01

2 470 Series Actuator Specifications Available Configurations See Actuator Configurations section Cylinder Pressure Maximum Allowable: 10.4 bar (150 psig) (but do not exceed maximum allowable thrust in table ) Required to Produce a Given Thrust: See figure 3 Minimum Recommended: 3.4 bar (50 psig) Maximum Rated Travel All Types: See table 1 Handwheel Information Travel Ratios for Types with Handwheels: Size 68 or smaller 16 complete wheel revolutions produce 5 mm (1 inch) of travel. Size 80 or larger 10 complete wheel revolutions produce 5 mm (1 inch) of travel. Thrust Information Produced by a Given Supply Pressure: See figure 3 Maximum Allowable Due to Actuator Construction: See table Stroking Speeds See table 3 Operative Ambient Temperature (1) With Nitrile O-Rings: 34 to 79 C ( 30 to 175 F) With fluoroelastomer O-Rings (optional) () : 18 to 104 C (0 to 0 F) With EPDM O-Rings (optional) () : 50 to 149 C ( 58 to 300 F) Piston Areas and Diameters See table 3 Yoke Boss and Valve Stem Connection Diameters See table 3 Construction Materials Actuator: Part Cylinder and Piston Piston Rod Extension Cylinder Seal Bushings O-Rings Yoke Snubber (if used): Part Cylinder, Reservoir, Piston, and Piston Rings Piston Rod O-Rings Material Aluminum S41600 (416) SST, Chrome Plate Brass Nitrile, Fluoroelastomer, or EPDM Class B cast Iron or WCB steel Class B cast Iron Material S41600 (416) SST, Chrome Plate Nitrile Options FIELDVUE mounting options 377 Series trip valve system to fail actuator up or down or lock in last position Type 304 electrical valve stem position switch Micro-Switch limit switches 1. These terms are defined in ISA Standard S Without a snubber, if this actuator has a snubber, the temperature specification is the same as the nitrile version. FIELDVUE Mounting Options For information on FIELDVUE mounting options for the Type 471 piston actuator, refer to the following Fisher Controls documents. Also see figure 10 for dimensions. Mounting FIELDVUE Instruments on Piston Actuators (PS Sheet 6.1:FIELDVUE(B)). FIELDVUE DVC5000 Series Digital Valve Controllers Instruction Manual, Form 5335.

3 Table 1. Maximum Rated Travel ACTUATOR SIZE w/ Snubber 7 Construction 16 Construction All Others 16 Construction All Others 16 Construction All Others 16 Construction All Others Spring Return ACTUATOR DESCRIPTION Other Types Clamp-Type Up Down Valve Stem Connector mm Inch mm Inch mm Inch 38 or / or Table. Maximum Allowable Thrust (1) per Actuator Construction TYPES WITH SPRING RETURN ALL OTHER TYPES ACTUATOR SIZE Cast Iron Yoke Steel Yoke Cast Iron Yoke Steel Yoke N Lb N Lb N Lb N Lb 60 30, , , , , w/handwheel 40, w/o handwheel 55,600 1, ,700 13,00 58,700 13,00 58,700 13,00 58,700 13, ,400 16,500 73,400 16,500 75,600 17,000 86,800 19, ,400 16,500 73,400 16,500 75,600 17, ,50 5, Stem material must be selected to withstand these loads. RANGE SPRING DETERMINES TRAVEL SPAN NOZZLE DETERMINES SENSITIVITY BIAS SPRING ADJUSTING SCREW DETERMINES CORRECT TRAVEL STARTING POINT W0701 / IL A183 1 / IL Figure Series Positioner Simplicity 3

4 3570 Series Positioner Specifications Available Configurations See 3570 Series Positioner Configurations section Input Signal Standard Ranges: 0. to 1 bar (3 to 15 psig) or 0.4 to bar (6 to 30 psig) Split Ranges: Typically uses one half of either standard range when two control valves are operated by one input signal from a single controller Optional Ranges: As required within the limits of the bellows Bellows Pressure Rating Standard Bellows: 3.4 bar (50 psig) Optional Bellows: 6. bar (90 psig) Supply Pressure Maximum: 10.4 bar (150 psig) Minimum:.4 bar (35 psig) Output Signal Type: Pneumatic pressure as required to maintain the correct valve stem position Action: Field reversible between direct and reverse (see table 4) Hysteresis (1)() 0.15% of total stroke or instrument pressure span Resolution (1)() 0.% of instrument pressure span Repeatability (1)() 0.3% of total stroke or instrument pressure span Frequency Response (1)() See figure 4 Pressure Connections Vent: 3/8-inch NPT All Others: 1/4-inch NPT Pressure Indications Type 3570C: Tire valves accept standard pressure gauge chucks All Other Types: See below TYPE OF INDICATION Positioner input signal gauge Cylinder (relay output) gauge NUMBER OF GAUGES USED Two-Relay One-Relay Positioner Positioner 1 1 STANDARD GAUGE RANGE 0-30 psi/0-0. MPa/0- bar or 0-60 psi/0-0.4 MPa/0-4 bar psi/0-1.1 MPa/0-11 bar Steady State Air Consumption (3) 0.54 normal m 3 /hr (0 scfh) with 6.9 bar (100 psig) supply pressure Operative Ambient Temperature (1)() With Nitrile O-Rings and Diaphragm: 34 to 71 C ( 30 to 160 F) With Fluoroelastomer O-Rings and Polyacrylate Diaphragm (optional): 18 to 104 C (0 to 0 F) With Fluorosilicone Diaphragm and EPDM O-Rings (optional): 50 to 149 C ( 58 to 300 F) Construction Materials Part Base, Cover and Beam Bellows Bias and Range Spring Relay Body Relay Nozzle(s) Diaphragm O-Rings Material Aluminum, Die Cast Brass Steel, plated Aluminum Stainless steel Nitrile or Polyacrylate/nylon Nitrile or Fluoroelastomer Options Type SS-5 clip-on chuck (with or without gauge) for Type 3570C positioner 1. These terms are defined in ISA Standard S For actuator with positioner only. Does not apply to other constructions or actuator-valve combination. 3. Scfh Standard cubic feet per hour (60 F and 14.7 psia); normal m 3 /hr normal cubic meters per hour (0 C and bar, absolute) 4

5 Table 3. Yoke Boss and Valve Stem Connection Sizes and Stroking Speed Information ACTUATOR SIZE EFFECTIVE PISTON STROKING 17 mm (5 inch) Dia. Yoke Boss PISTON 90.5 mm (3-9/16 inch) Dia. Yoke DIAMETER SPEED and 5 mm (1 inch) or 3 mm AREA (1) Boss, and 19 mm (3/4 inch) Dia. (1-1/4 inch) Dia. Valve Stem Valve Stem Connector or 16 mm Connection or 5 mm (5/8 inch) Pin Dia. Clevis (1 inch) Pin Dia. Clevis cm Connection Inch mm Inch mm/s Inch/s Connection For actuator only, with all prestroke conditions satisfied. Stroking speeds for actuators with positioners, spring returns, snubbers, or handwheels will depend on the particular configuration involved Table 4. Action Under Normal Operating Conditions ACTUATOR DESCRIPTION Direct-acting With positioner Reverse-acting Without positioner 1. Supply pressure is routed through relays to piston. Down Increasing input signal pressure to bellows (1) Decreasing input signal pressure to bellows (1) Supply pressure loaded on top of piston, exhausted from bottom DESIRED PISTON MOTION Up Decreasing input signal pressure to bellows (1) Increasing input signal pressure to bellows (1) Supply pressure loaded on bottom of piston, exhausted from top NOTES: 1 THRUST RATING IS BASED ON MAXIMUM CAPABILITY OF ACTUATOR (ONLY) AT 1 C (70 F) MAY BE INCREASED BY 10% FOR ACTUATORS WITHOUT POSITIONERS. EITHER THIS THRUST, OR THE MAXIMUM ALLOWABLE LOADING FOR THE CONTROL DEVICE IS THE LIMITING FACTOR FOR USABLE ACTUATOR FORCE CH7640 C A184 4 / IL 1 Figure 3. Supply Pressure and Thrusts 5

6 -7 Added to the Type Number: Provides 10 mm (4-inch) maximum travel for standard actuators, available in size Added to the Type Number: Provides 03 mm (8-inch) maximum travel for standard actuators or 06 mm (8-1/8 inch) for clevis-connected actuators, available in sizes 60, 68, 80, and Series Positioner Configurations 1. SIZE mm (1-1/ INCH) TRAVEL. SIZE mm (-INCH) TRAVEL K555 B A185 3 / IL 3. SIZE mm (-INCH) TRAVEL 4. SIZE mm (3-INCH) TRAVEL Figure 4. Frequency Response for 470 Series Actuator with 3570 Series Positioner Actuator Frequency Response Figure 4 shows how various size actuators respond when the input signal pressure is cycled at small amplitude (3 to 5 percent) and increasing frequency. Assume cycling input pressure and the movement of the actuator rod are represented by sine waves. As the actuator stem is forced to move faster, its motion begins to fall behind the input in both time (shown as phase lag) and amplitude (shown as normalized gain). Both of these parameters are affected by cylinder volume and, consequently, changes are more pronounced in the larger constructions. Type 3570 Valve positioner with two relays and three pressure gauges for monitoring input signal and output pressures to the top and underside of the actuator position. Not for use with the Type 47 or 473 piston actuators. Type 3570C Similar to Type 3570 except that positioner is equipped with automotive tire valves instead of pressure gauges. The valves can be used for clipon test pressure gauges. The relay nozzles on these positioners are locked in place with locknuts to resist unwanted nozzle movement due to vibration. Type 357 Valve positioner with one relay, normally used on the Type 47 actuator with valve bodies having push-down-to-open action. The positioner has two pressure gauges for monitoring input signal and relay output pressure to the top of the actuator piston. Type 3573 Similar to Type 357 except that the relay output pressure is piped to the underside of the actuator piston. This positioner is normally used on the Type 473 actuator with valve bodies having push-down-toclose action. Actuator Configurations Type 471: Pneumatic piston actuator with Type 3570 positioner. Type 47: Pneumatic piston actuator with Type 357 positioner and push-up spring return. Type 473: Pneumatic piston actuator with Type 3573 positioner and push-down spring return. The Type 471, 47, and 473 actuators can be supplied with the following accessories Series Positioner Type DVC500 Digital Valve Controller Snubber Handwheel Clamp-style valve stem connectors and 38 mm (1-1/ inch) through 76 mm (3-inch) maximum rated travels. Principle of Operation Actuator These actuators react to a pressure unbalance that is created by loading supply pressure on one side of the piston and unloading the opposite side. Some type of switching device is required to shift the supply pressure from one side of the piston to the other. For Type 471 piston actuators, this device is the Type 3570 positioner; Type 47 uses the 357 and Type 473 uses the 3573 positioner. A separate loading device must be provided for piston actuators without positioners. For actuators with 3570 Series positioners (figure 5), the pneumatic output signal from a control device is piped to the bellows. As long as the bellows receives a constant input signal pressure, the beam remains motionless and allows supply pressure to bleed through both relay nozzles such that a constant pressure is maintained between the nozzle and the fixed orifice. 6

7 The nozzle pressure in relay A increases due to the restriction created by the beam over the nozzle. Through relay action, the air pressure to the top of the piston is increased. At the same time, relay B reacts to the change in beam position to decrease the pressure to the underside of the piston. Due to the resulting unbalance forces acting on the piston, it moves down, changing the valve plug position. Piston movement is fed back to the beam by a range spring connected to the beam and to the piston rod extension, applying a force to the beam opposite to that caused by the expanding or contracting bellows. This feedback arrangement prevents over-correction and ensures a definite position of the piston and valve plug for a given instrument signal. If upward piston motion is required, the beam pivots to cover the nozzle on relay B. The result is relay, piston, and feedback action opposite that for downward piston motion. Reversal of 3570 Series positioner action is accomplished simply by removing four screws, inverting the bellows, and installing two bellows posts for support if the change is from direct to reverse action. Bellows posts are stored in the positioner case and are not used if the change is from reverse to direct action. BH771 B A / IL Figure 5. Operation of Actuator with 3570 Series Positioner The relays are in equilibrium with their inlet and exhaust valves closed. Assume that a downward piston motion is required and the bellows receives a corresponding change in input signal pressure. This causes the beam to pivot so that it covers the nozzle on relay A. (Beam movement is accomplished either by increasing the input signal pressure on a direct-acting positioner to expand the bellows, or by decreasing the input signal pressure on a reverse-acting positioner to contract the bellows.) Actuator with Spring Return (figure 6) A spring can be added to the actuator to move the actuator piston and in turn the control valve plug or ball to one limit or the other of its stroke if the loading pressure fails. An actuator with spring return may have no positioner, or a one-relay positioner as shown in figure 6. One-relay positioners are used so that the valve stem will not be overloaded by the loading force added to the spring force, and work as follows: Actuator with Push-Up Spring Return (Type 47) The positioner used is the Type 357, which has relay A only. Supply pressure is routed just to the top of the piston, and the spring provides the entire force pushing up on the bottom of the piston. 7

8 CR4006 A B0670 / IL CR4007 A Figure 6. Operation of Actuator with Spring Return Actuator with Push-Down Spring Return (Type 473) The positioner used is the Type 3573, which has relay B only. Supply pressure is routed just to the bottom of the piston, and the spring provides the entire force pushing down on the top of the piston. Actuator with Snubber (figure 7) As the actuator piston strokes, the snubber piston moves inside an oil-filled cylinder, forcing oil from one side of the piston to the other through two check valves. The resistance to flow created by the settings of the check valves and the shock absorbing quality of the oil combine to damp out any tendency of the valve plug to jump. The plug of each check valve is held off its seat by the positioning of the adjusting screws. Thus, with the adjusting screws backed off all the way, maximum damping will be obtained. Actuator with Handwheel (figure 8) The handwheel version can be used to open or close the valve manually (either during normal operation or in an emergency), to position the valve at any point in the stroke, or to act as a travel stop on one end but not both at the same time of the valve stroke. The tapered pin must be inserted for manual operations, but left out (except on some long-stroke constructions) in travel stop use. Pin insertion is optional, but recommended in emergency or closing situations. All handwheels used with the 470 Series are sidemounted, and come with a spring-loaded ball detent to prevent setting changes due to vibration. Handwheels for most types are either 03 mm (8 inches) in diameter with beveled gears or 43 mm (17 inches) in diameter with worm gears. The exception is handwheels used on actuators with a spring-return that are either 305 mm (1 inches) or 356 mm (14 inches) in diameter. Installation The actuator may be installed in any position, but normal installation is with the actuator vertical above the valve. Dimensions are given in figures 9 and 10. 8

9 3A86 A A130 1 / IL W / IL Figure 7. Operation of Actuator with Snubber Figure 8. Actuator with Handwheel 9

10 148 (5.81) 6 57 (.5) mm INCH NOTES: 1 OMIT FOR TYPES WITHOUT SNUBBERS. OMIT FOR TYPES WITHOUT 3570 SERIES POSITIONERS. 3 DIMENSION IS 111 mm (4.38 INCHES) FOR TYPES WITHOUT 3570 SERIES POSITIONERS. 4 DUPLICATED ON OPPOSITE SIDE: EACH HOLE IS 5/16 18 UNC B AND TAPPED 13 mm (0.50 INCHES ) DEEP 5 HANDWHEEL IS CENTERED ON YOKE ON SIZE 68 AND SMALLER; OFF CENTER ON LARGER SIZES. 6 WHEN USING TYPE 377 TRIP VALVE MANIFOLD, ADD ADDITIONAL 55 mm (.1 INCHES). BR101 B A341 / IL Figure 9. Dimensions with 3570 Series Positioner 10

11 DIMENSIONS IN MILLIMETERS E (6) H I ACTUA Spring Return TOR Clevis (-8) -16 or Spring Constructions Handwheel Spring SIZE C D or -7 Long Long All All Return All (5) (-5) Return Up Down Stroke Stroke Others Others Construc Others Construction Constructions (-) (-3) Construction Construction tions S (1,) 541 (1,,3) 865 (1) 644 (1) 1034 (5) 594 (1) (1) 1094 (5) 759 (1) () 145 (,4) 1386 (4) (5) 856 (4) (,4) 1451 (,4) 145 (,4) 145 () 1386 (4) (5) (4) 1000 (4) Snubber also available in this size and construction; add Handwheel also available in this size and construction; for size 60 use same dimension; for size add construction may also be included in this size; add Snubber also available in this size and construction; add Handwheel also available in this size and construction; add When using top-mounted Type 377 Trip Valve manifold, add additional 54mm. DIMENSIONS IN INCHES E (6) H I ACTUA Spring Return Clevis (-8) -16 or Constructions Handwheel Spring TOR C D Spring or -7 Long Long All All All S (5) SIZE (-5) Return Return Up Down Stroke Stroke Others Others Others Construction Constructions Constructions (-) (-3) Construction Construction (1,) 1.31 (1,,3) (1) 5.37 (1) (5) 3.37 (1) (1) (5) 9.87 (1) () 56.1 (,4) (4) (5) (4) (,4) 56.1 (,4) (4) (,4) 56.1 () (5) Snubber also available in this size and construction; add Handwheel also available in this size and construction; for size 60 use same dimension; for size add construction may also be included in this size; add Snubber also available in this size and construction; add Handwheel also available in this size and construction; add When using top-mounted Type 377 Trip Valve manifold, add additional.1 inches (4) (4) Figure 9. Dimensions with 3570 Series Positioner (Continued) 11

12 SIZE C E (1) P SY AR mm Inches mm Inches mm Inches mm Inches mm Inches Refer to figure 9 to derive E dimensions for additional actuator constructions with FIELDVUE Digital Valve Controllers. Using figure 9, calculate dimension E values for actuators WITHOUT 3570 Series positioners. These calculated dimensions are valid for actuator constructions with FIELDVUE Digital Valve Controllers. FAIRCHILD MODEL NO C AR SY P E TYPE DVC500 1/-14 NPT CONDUIT CONN BOTH SIDES 1/4-18 NPT SUPPLY CONN 17B9498 B E01 / IL mm INCH Figure 10. Dimensions with FIELDVUE Digital Valve Controller FIELDVUE, Fisher, Fisher-Rosemount, and Managing The Process Better are marks owned by Fisher Controls International, Inc. or Fisher-Rosemount Systems, Inc. All other marks are the property of their respective owners. Fisher Controls International, Inc. 1990, 000; All Rights Reserved For information, contact Fisher Controls: Marshalltown, Iowa USA Cernay France Sao Paulo 0544 Brazil Singapore Printed in U.S.A.