Preventative Maintenance for Bettis D-Series Rack & Pinion Pneumatic Actuator

[Mattpdrexel]

Hi all,

What would be the appropriate preventative maintenance plan for a D-Series Rack & Pinion Pneumatic Actuator? The actuator operates in mild service conditions and has acted reliably for the past ten years. I do not have much industrial experience, so I have no basis for selecting a maintenance plan for pneumatic actuators.

See attachment for actuator details.

Thanks!

 

[thost]

My opinion is that you should not open an actuator of this type unless it is necessary. There is a greater chance of damaging anything than prolong the life of the actuator.
A visual inspection and functional test shall be a sufficient maintenance. The frequency of maintenance should be driven by the criticality of the valve

 

[Mattpdrexel]

Thost,

Thanks for the validation, I was heading in that direction. Will be removing the preventative maintenance task now, make the maintenance guys happy.

 

[gerhardl]

To support Mattpdrexcel (totally agree):

This type of actuators will generally operate a great number of times without failure. On the other hand a long stop-time could wear as much as a very high frequency of repetitive operations.

Main failure components:
Solenoids (not actuator)
Leakage over piston sealings (Test for leakage with solenoid(s) demounted.)
Excessive wear(seldom)
Actuator itself (torque) selected too small.

Main failure causes:
Dirt, water and excessive oil in air (most modern pneumatic systems are oilfree), condensation in air.
Maladjustment (end-stops of actuator), loose or unfit connections to valve.
High voltage peaks to solenoids.
Valve wearing gives higher torque over time.

Preventive by installation: Recheck and improve pneumatic system with all necessary components (water and dirt filters, draining), control correct mounting and el. and mechanical operation and adjustment of complete installation.
During operation: None, check correct operation at the the total systems check intervals.
By failure: replace complete valve and actuator. Often not economical to repair.

Good luck!