PRINCIPLE OF OPERATION
The Compact II actuator is a pneumatic quarter-turn Rack
& Pinion actuator. Air pressure applied to the piston surface
area generates thrust which transforms linear motion to
rotary motion of the pinion. The Compact II has four pistons
centrally located around one pinion. This means that the
actuator can generate twice the torque of dual l piston
actuators, is lightweight, occupies minimum space and has
minimal air consumption.
Installation, Operating & Maintenance instructions
PAGE 3
Supply Pressure
The supply pressure for the Compact II actuators are as
follows:
Double-acting: 2-8 barg (30-120 psig).
Spring-return: 3-8 barg (40-120 psig).
Spring-return actuators can also operate with air pressure
of 2 barg (30 psig) by using the appropriate spring
configuration as shown in the Compact catalogue. When
sizing an actuator to available air supply, make sure you
have adequate power in the actuator to allow the valve to
complete its operation and leave enough power for safety
margin.
Temperature
The standard temperature limits for the Compact II actuators
are -20
°
C (-4
°
F) to +80
°
C (+176
°
F). For temperatures below
or above these figures special preparation and materials are
required such as grease, O-rings, pinion bearings and pads.
The Compact II maximum working temperature is 130
°
C
(266
°
F) when used with Viton O-rings and HT grease.
The Compact II minimum working temperature is -40
°
C (-
40
°
F) when used with EPDM O-rings and LT grease.
For temperatures below -40
°
C (-40
°
F) please consult with
Compact.
When used in sub-zero temperatures it is essential to use
an air dryer for the supply to avoid any moisture.
Always consult with a representative of Compact II for
suitability and recommended practice.
AIR CONNECTIONS
The actuator air connections are marked A and B.
Port B connects to a chain of holes to all the four pistons. The air
passes into the Namur cover (or insert) and through holes which are
connented to the two neibouring pistons. Each piston recieves the
air flow from two directions which ensures a quick response.
In sizes C15 to C45 port A is to
the right and port B to the left.
A
B
Pressure entering port A into the
center chamber pushes the
pistons outward and rotates the
pinion CCW
A
B
Pressure entering port B into the
outer chambers pushes the
pistons inward and rotates the
pinion CCW
In sizes C60 and C75 the air
connections are vertical where
port A is above port B.
A
B
B
A
Double Acting (DA)
Pressure entering Port A to open:
Center chamber pressurized. Pistons move outward and the pinion
rotates counter clockwise (CCW).
Spring Return (SR)
Pressure entering Port A to open:
Center chamber pressurized. Pistons move outward and
the pinion rotates counter clockwise (CCW).
Springs are compressed.
Pressure entering Port B to close:
Outside chambers pressurized. Pistons move inward and
the pinion rotates clockwise (CW).
drawing 1.
