Double acting vs single acting actuator 1

[helpyou]

Hi

How we can select between single acting vs double acting actuator. What is the criteria or requirements to base decision on?

Thank you

 

[georgeverghese]

For the same supply air pressure, a double acting actuator develops more torque than a single acting actuator. Conversely, a double acting actuator is smaller than a single acting one for a given required torque.

On the other hand, from recollection, a double acting actuator has no failsafe position on loss of instrument air, and they fail put in the last position. Single acting actuators can be made to fail open or fail close on loss of IA. So choose a double acting actuator only when there are no safety or operating issues with the valve being partially open (or closed) on loss of IA, and if you need a more compact actuator.