The invention relates to a method for operating a process valve
assembly (20) comprising a process valve (1), a
pneumatic valve actuator (3) for actuating the process valve (1), and a control device (4) for pneumatically actuating the
valve actuator (3), comprising the following steps performed by the control device (4): pneumatically actuating the
valve actuator (3) with a
working pressure to perform a partial
stroke test with a valve member (2) of the process valve (1), acquiring pressure values (dw1, dw2, ..., dw8) of the
working pressure and position values (pw1, pw2, ..., pw8) of the valve member (2) during the partial
stroke test, detecting multiple successive partial
stroke test events occurring during the partial stroke test, and for each detected partial stroke test event, determining a respective
data point (dp1, dp2, ..., dp8), which includes at least one pressure value and one position value, and storing the determined data points as a
data set.