PNEUMATIC ACTUATOR
Note:
For optimal operation, pneumatic actuators should be run with a supply of
clean, lubricated air.
Spring Return Actuator Operation
Air to PORT 2 (the left hand port) causes the actuator to turn counterclockwise
(CCW). Loss of air to PORT 2 causes air to exhaust and the actuator turns clockwise
(CW). This is the FAIL CLOSE operation.
Double Acting Actuators Operation
Air to PORT 2 (the left hand port) causes the actuator to turn counterclockwise
(CCW). Air to PORT 1 (the right hand port) causes the actuator to turn clockwise
(CW).
Pneumatic Actuator Maintenance
Routine maintenance of pneumatic actuator:
• Keep the air supply dry and clean
• Keep the actuator surface clean and free from dust
• Periodic checks should be done to make sure all fittings are tight
• Pneumatic actuators are supplied with lubrication to last the entire life span of
the actuator under normal operating conditions.
The outer surface of the pneumatic actuator should be clean to avoid friction
or corrosion. All fittings and connections should be tight to prevent leaks during
operation. Check the bolts mounting the valve to the actuator to make sure they
have not come loose during shipping or installation. Make sure the valve and
actuator are not rubbing or jamming against other components during operation.
The actuator should be inspected annually to make sure all fittings and bolts are
tight and nothing has come loose during operation.
Disassembling Pneumatic Actuators
Before beginning disassembly, ensure that the air supply to the
actuator has been disconnected, all accessories have been
removed, and that the actuator has been disassembled from the valve.
1. Loosen the end cap fasteners (23) with a wrench (size varies depending on
actuator model). On the spring return actuator, alternate 3 to 5 turns on each
fastener until the springs are completely decompressed. Use caution when
removing the cap since the springs are under load until the fasteners are fully
extended.
2. Remove the pinion snap ring (13) with a lock ring tool. The indicator (12) may
now be removed.
3. Turn the pinion shaft (2) counter clockwise until the pistons are at the full end
of travel. Disengage the pistons (15) from the pinion. (
Note:
Low pressure air-
-3 to 5 psi MAXIMUM--might be required to force the pistons completely from the
body.) Note the position of the pistons before removing them from the actuator
body.
4. Remove the pinion through the bottom of the actuator. The actuator is now
completely disassembled.
WARNING
Be sure the actuator surfaces are free of debris and scratches
before reassembling.
1. Apply a light film of grease to all O-rings and the pinion before replacing.
2. Put the pinion (2) back through the actuator with the flats of the pinion shaft
running parallel with the body.
3. When reassembling the actuator, make sure that the piston racks are square to
the actuator body and returned to their original orientation. (
Note:
The normal
operation of all spring return pneumatic actuators is FAIL CLOSED. To change
the orientation to FAIL OPEN, rotate the racks 180º to create a reverse operation.
4. When replacing springs in a spring return actuator, ensure that the springs are
replaced in their identical position in the end cap from which they were removed.
(
Note:
In some circumstances, you might want to change the standard 80 pound
spring set to fit your application and available air pressure.)
5. Seal the end caps with a petroleum lubricant and bolt to actuator body.
6. Check the seal of the actuator by covering seal areas (pinion, end caps) with
soapy water and using low pressure air to the actuator to ensure that no bubbles
are produced.
WARNING
Reassembling Pneumatic Actuators
Failures
Inspection Items
Corrective Action
Pneumatic
actuator
won’t operate
1. Check the solenoid valve. Is the
coil burnt out or is the solenoid
spool?
2. The actuator will not move
because of debris in the gears.
3. The pneumatic line to the
actuator is distorted or smashed.
4. The pneumatic line is frozen
because of low temperatures and
moisture.
1. Replace the solenoid
valve coil or remove debris.
2. Disassemble the actuator,
clean the debris and
reassemble the actuator.
3. Replace pneumatic line to
the actuator.
4. Warm the pneumatic lines
and remove moisture from
supply lines.
Pneumatic
actuator runs
slowly
1. The air supply pressure is
insufficient.
2. Are other pneumatic devices
consuming the air required for the
actuator to operate?
3. The pneumatic actuator is
undersized for the application.
1. Increase the air supply
pressure and look for leaks
in the supply pressure
pipeline.
2. Increase the air supply
or reduce the number of
devices operating at the
same time.
3. Replace the actuator with
a larger actuator.
4
When working on the Actuator/Valve assembly, disconnect the
air or power supply to the actuator. Spring return actuators/
valves may change position if power fails or is removed. Never insert any object or
body part into the valve body. Severe injury may occur.
WARNING
