DIAGNOSTIC APPARATUS AND METHOD FOR FLUID CONTROL VALVES

Apparatus and method for diagnostically testing and determining the operating condition of a pneumatically operated valve. A diagnostic controller is connected to a valve actuator assembly so that diaphragm pressure and valve plug movement among other inputs can be sensed while the valve actuator assembly is stroked through a test operation cycle. The sensor output signals are then used in selected graphical plots to provide information which can be analyzed to indicate the condition of the valve in such areas as spring adjustment, stroking time, valve travel, stem friction, seat load, and positioner and transducer calibration.