General Valve application ? 1

[chungming]

does the motorized valve always came with hand wheel also. I just queries, that what will happen if the motorized valve don't work & can it open manually ?

 

[gerhardl]

No, this is depending of how the actuator (electrical motorize device) is constructed. Most larger, well equipped actuators will have a handwheel as a standard, but not all.

Some smaller 90. deg. electrical actuators without handwheel might be constructed with square spindle allowing movement 90 deg by wrench or similar.

Advice when specifying: 'with handwheel for manual operation' to be included as one of the specifications.

And to answer your question: if not equipped with handwheel or for wrench operation: you will have to demount the actuator to free the valve spindel for manual operation. In some cases this could be unsafe as the actuator could be an active element in the locking in place and/or sealing of the valve.

 

[Unotec]

Can't you just put a manual valve in front of it?

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[Joesteam]

We prefer to use bypass globe valves instead of handwheels on control valves. Both will let you run the process manually in case of control valve failure.
However, a handwheel on the control valve often can override the valves failure mode and could lead to safety issues. Also, with a bypass, you can repair/replace the control valve while still running the process.

Joe Lambert

http://www.control-associates.com/

 

[JLSeagull]

By motorized valves I assume that the question applies to electrical motor operated isolation valves. These are not fail-safe and are not typically used for throttling.