On the bench, with the valve isolated from any line pressure, the actuator should start moving at the low end of the range and reach full travel at the high end, for example 3 to 15 psi. Techs adjust spring compression to hit the published bench set. In service, process forces and packing friction shift the operating range, which is why a valve that strokes fine on the bench can still fail to seat in the line.
Bench set's supposed to be 6 to 30, it starts moving at 9, back the spring adjuster off a couple turns.
Also heard as
- spring range
- bench range
Related terms
Actuator
The powered device that opens, closes or positions a valve using air, hydraulic oil or an electric motor.
Positioner
A device on a control valve that compares the control signal with actual valve position and adjusts air to match.
Stroke
To run an automated valve through its full travel to prove it moves, seats and reports position correctly.
Spring-return
Describes a single-acting actuator that uses air to move one way and a spring to move back and fail safe.