BY ACTUATION
Manual Valves
Where the operating energy comes from — the line itself, a handwheel, or an external actuator.
Choosing Manual Valves
Manual operation may use a lever, handwheel or gearbox. Access and required effort must be considered together with valve size and closing differential. A manually operable valve can still be impractical if the installation has insufficient clearance or requires frequent operation from an inaccessible position.
What to include in the RFQ
- Provide operator access, handwheel/lever clearance and operating frequency.
- Request operating torque or thrust under the maximum differential.
- Define indication, locking, gearbox and any extension requirement.
Selection scenario
For an overhead valve, review the access arrangement and how operators identify its position before selecting the operating mechanism. A photograph of a handwheel does not resolve these site conditions.
Common selection mismatch
Manual override on an actuated valve should be assessed separately from the normal operating mechanism and its isolation procedure.