Pneumattralfy o~~tatecl f>iston actuator with l”tEgrafly mounted Type 3570 positioner. Actuator is yokeless, has 4” maxfmum trael. and is fastened 10 the actuatw mounting plate of many prel970 Veer -Ball@ ~afves and Fisher butterfly valves. Actuator sizes 30. 40, 60. 80, 100, and 130.
Same as Type 480, hut for on/off service. Positmner is replaced with a pressure tap cwer which is Molted to the top of the cylinder.
Same as Type 480. but tioner is replaced with 3579 solenoid manifold permfs supply pressure loaded and exhausted sponse to electrical signals.
positioner Tvpe 480 actuators.
pow Type which to be in rep
Standard solenoid manifold basic to Type 489 actuatws.
Type 480,481, Actuators I FISHER”~
Inspect this equipment on arrival to Nate any damage which may have occurred in transit. If the actuator is attached to a valve body when received. install the valve in the pipeline with flow in the direction of the an~w on the salve body. (Some valve types, notably various butterfly valves. can be installed with flow in either direction and are unmarked as to proper flow direction.)
A three-valve bypass around fhe main valve is recommended to permit c~nt~nu~~s operation during periodic matntenance or inspection of the main valw
When Series 480 actuators are supplied to operate dampers, louvers. or similar equipment, a suitable mounting plate should be provided, and the piston rod of the actuatw connected to the operating arm of the damper, etc., with appropriate hnkage.
Type 480.. ISee Figure II - The pneumatic pressure signal from the instrument or controller is piped to the bellows of the 3570 positioner. Assume that the porltmner IS direct-acting and that the instrument signal has increased. The bellows expands and m~,ves the beam, which pivots around the fixed pmnt and simultaneously uncwers the nw zle of relay “B” and COYUS the nozzle of relay “A”. Relay “A” nozlle pressure increases due tq the restriction created by the beam over the nuzzle. Through relay action, the air pressure tO the top of the piston increases. Rep lay “B” reacts to the change in beam pqsltx,” to decrease the prersure on the underside of the piston. Due to the unbalanced pressures acting on the plst~n, it mwes down, changing the position of the actuator stem and returning the controlled element to the desired value. A feedback arrangement consisting of a range spring between the beam and the piston rod extension prevents over-correction and ensures a definite position of the piston for a given
Figure 2 instrument signal. thus giving stable and accurate response to a change in controlled conditions.
Upon receiving a decreasing instrument signal, the reverse of the above actlo” takes place. The bellows contracts and the beam pivots, restricting the nozzle of relay “B” and uncovering the nozzle of relay “A”. Through relay action. the pressure below the actuator piston increases and the pressure above the piston decreases to move the piston upward.
ISee Figure 21. Operation of either a Type 481 or a Type 489 is similar to a Type 480 in so far as basic piston movement is concerned. However, the manners of loading the respective pistons are less complex. On the Type 489 actuators. the 3579 solenoid manifold acts to alternately load and exhaust full supply pressure to opposite sides of the piston in response to electrical signals from an outside power source. The 481, used most frequently for on/off service, must have an external switching device attached to divert supply pressure from one side of the piston to the other.
///ustra don of a Type 3579 manifold
Type 48%. The Type 3570 positioner, an ins tegral part of Type 480 actuator units, is factory-assembled to the actuator. Two connections, “Supply” and “Instrument”. remain to be made after valve installation. Both are 114” NPT holes in the positioner and are labelled. Minimum supply pressure is 35 psig. but for optimum performance, supply pressure should be held as near as possible to the 150 psig maximum. Supply pressure air or gas should be clean and dry, as well as non-corrosive. Use of a Fisher Type 254 filter is rep commended. The
ways be vented to prevent pressure buildup. If the valve is installed with the actuator below the pipeline, provide a new vent location in the lowest part of the case by removing the cadmium plated pipe plug from the case and screwing it into the standard vent location. This also serves as a drain hole to prevent accumulationof condensate. Types 481 and 489.. The Type 481 and actuators also require l/4” Supply pressure piping.
Type 489 NPT male The 3579
solenoid manifold used or the Type 489 has three external connections. Supply air enters the side of the ~nant~ fold. Depending on the controller signal to the solenoid YBIYBS. the XIIIply air is directed either straight down to the top side of the piston. or out the bottom cylinder connection lin side of manifold adjacent to supply port) and through tubing to the lower side of the piston. During loading of piston, the air on the opposite side of the piston is exhausted through the w haust port of the manifold. The Type 481 has only a pressure tap cover on top of the cylinder. Sups ply air pressure must be connected to it. and also to the lower cylinder connection located near the cylinder/cylinder flange joint. An external four-way valve or other switching dewe must be provided between the maw supply pressure line and these two actuator pressure connect,ons.
Adjustments All three adjustments on the Type 480 actuator are on the Type 3570 positioner. For further information on the positioner, such as Adjustments. Maintenance. Reversing. and Relay Operation, refer to the Type 3570 Ins structions and Parts List, Form 1837. Types 481 and 489 require no adjustments.
Types 480,481, Actuator
It is necessary for efficient and proper operation of the actuator that all parts be free from dirt, abrasives. and foreign materials. Upon assembly at the factory. all synthetic rubber O-rings have been coated with LUBRIPLATE 130.AA, a special lubricant manufactured and distributed by Fiske Brothers Refining Company of Newark. New Jersey, and Toledo. Ohio. It is recommended that his lubricant ,be used on all O-rings, especially those on moving parts or in contact with moving parts. whenever the actuator is dismantled. To disassemble a Fisher piston actuator, proceed as follows: (References to “positioner” can be ignored if either a 481 or a 489 actuator is involved.1 1. Bypass the valve body or shut off the pressure in the pipeline. Caution: The adjustable linkage between the actuator and the main valve should not be disconnected when the valve is open with fluid flowing. (Dampers or louvers should be in safe.
2. Shut off all pressure to the actuator. Remove all tubing lines Icylinder. instrument, and supply) from the actuator. 3. Remove positioner cover after loosening the four cover screws on the underside of the positioner base. 4. Disengage range spring by un~ screwing the spring retainer from the piston rod extension. 5. Loosen the two cap screwy that hold the positioner to the cylinder. When removing the positioner. do not lose the small O-ring that is used in the passage from the positioner to the top of the cylinder. 6. Next remove the clevis bolt from the adjustable linkage. Remove the bottom snap ring (Key 26) and unscrew the cleuis and the boot locknut from the actuator piston rod. 7. Remove the nuts that hold the cylinder to the mounting flange and lift off the cylinder. 8. Remove the stud bolts (Key 13) that hold the cylinder to the cylinder flange. Two slots. 180” afx,rt. are lo
cated at the lower edge of the cylinder. Insert a screwdriver in these slots and pry the cylinder loose. The pet011 and piston rod will come out with the cylinder. The piston can then be removed by pulling it out the open end of the cylinder, 9. Unscrew both seal bushings, (Keys 7 and 8). 10. Inspect all parts for eXcessi”e wear and defects. Replace all worn O-rings. Lubricate as mentioned above. 11, To reassemble, reverse the above procedure.
Always include the serial number of your actuator when consulting your representative for technical advice or ordering replacement parts. Also include the complete part number listed in, the following parts reference sec. fion. (Some valve types. notably butterfly valves. do not have the same valve serial number as the actuator. Therefore. for proper cross reference, always include the valve serial number if it differs from the actuator serial number.)
480, 481, & 489 Parts
Figure 4. Type 481 actuator.
45 SpringRetainerSpacer.SST ,T”pe 480 only1For 2” 0‘ lesstrwe, .,.I2233 4617 78’ cover sea,.S”“. Rubber (Type481onlyl lCS5380699 79 cover screw.Steel.CDPL lT”w 481only, ?A34492405 160 PipePlug.Steel
‘ Recommended SparePart
Published on Jun 26, 2011
Fisher Controls instruction manual, courtesy of RMC Process Controls & Filtration, Inc. & www.RegulatorParts.com. Repair kits, orifices, dis...