When should a positioner befitted A positioner should be considered in
the following circumstances • When accurate valve positioning is required
• To speedup the valve response. The positioner uses higher pressure and greater airflow
to adjust the valve position • To increase the pressure that a particular actuator and valve can close against. (To act as an amplifier
• When the valve pressure drop at
the maximum operating flowrate, exceeds 5 bar for single seated valves or 10 bar for double seated valves
• To linearize
a nonlinear actuator • Where varying differential pressures within the fluid would cause the plug position to vary
• When controlling with
wide throttling range and • When valves are handling sludge or solids in suspension. Furnish positioners for all control valves in critical service and where the variable,
such as flow, has to be closely controlled. Specify that the positioner be furnished with the control valve or damper instead of separate procurement.
Share with your friends: 
