Pneumatic (Air) actuators usually offer lower pricing than electric
actuators plus the ability to easily return to a normally closed (or open) position in the
event of a system or power failure. The cycle time for the pneumatic valve to
actuate is under a second compared to an electric valve cycle time of 5 to 10
seconds. Air pressure, when actuated, pushed against a piston with the force
transferred to a rotating force turning the ball within the valve - the rotation is
normally 90 degrees. The ability to continuously adjust the valve opening position
in a process control system is not possible when using pneumatic actuators. For fail safe operation, the air piston works against a spring
that will return the valve to the original position when air pressure is released.
A three way air pilot valve is required to control the operation.
The actuator can be made in a double acting (or air x
air) mode that will require air pressure to open and close the valve. A spring
return is not used in this case. A four way air pilot valve is required to control
the operation.
Electric actuators offer the
advantage of operation with using electricity only. An electric motor within the
actuator is gear driven to rotate the ball within the valve. Rotation of the
actuator can be 90 degrees reversing, 180 degree reversing (for three way valves) or one
direction with stops at 90 degree positions. Two electrical circuits are required -
one for opening and one for closing. The valve will not return to a safety position
in the event of a power failure without the use of a secondary battery power supply
system. Actuators can easily provide signal relays that advise the position of the
valve for control systems. The GF "EA" Series actuator offers options to control
the position of the valve or the cycle time. In addition to 110VAC power supplies,
actuators are available for 12 or 24volt AC or DC power.
|
|
Plast-O-Matic Valves -
Actuated Valve Pneumatic and
electric - 2 & 3 Way
PVC, CPVC, Polypropylene and PVDF
True Union Connectors - 1/2" - 2"
Plast-O-Matic Click Here
|
George Fischer -
Actuated Valves Pneumatic and
electric - 2 & 3 Way
PVC, CPVC, Polypropylene and PVDF
True Union Connectors - 1/2" -6"
George Fischer Click Here
|
|
Spears
Manufacturing
-
Actuated Valve Pneumatic
and electric - 2 Way
PVC
and CPVC
Compact
or True
Union Connectors - 1/2" - 2"
Spears
Manufacturing Click
Here
|
InLine
- Actuated Valve 316SS
- 2 & 3 Way
one,
two & three piece designs
Threaded,
flanged, sanitary
InLine
Click
Here
|