Types 480,481, & 489
Fisher Controls
Instruction Manual
Type 480,481, and 489
Actuators
I FISHER”~
March 1971 Form 2367A
Actuator Specifications
Type NumberDescription
480 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 butter-
fly valves. Actuator sizes 30.
40, 60. 80, 100, and 130.
481 Same as Type 480, hut for
on/off service. Positmner is re-
placed with a pressure tap cwer
which is Molted to the top of the
cylinder.
489 Same as Type 480. but pow
tioner is replaced with Type
3579 solenoid manifold which
permfs supply pressure to be
loaded and exhausted in rep
sponse to electrical signals.
3570
Standard positioner basic to
Tvpe 480 actuators.
3579 Standard solenoid manifold
basic to Type 489 actuatws.
Installation
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.
Principle of Operation
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 pres-
sure 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
Types
480,481, & 489
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 be-
low the actuator piston increases and
the pressure above the piston decreases
to move the piston upward.
Types 481 and 489..
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 op-
posite 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.
Figure 2 ///ustra don of a Type 3579 manifold asserr~bly.
Pressure Connections
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 positioner case should al-
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 Type 489
actuators also require l/4” NPT male
Supply pressure piping. 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 ad-
justments.
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