Process valve apparatus and method

A process valve apparatus comprising:

• a process fitting with a valve member;
• a pneumatic valve drive for actuating the valve member;
• and
• a control device with a pneumatic valve device for pneumatic actuation of the valve drive, the control device being configured to carry out a partial stroke test and, within the partial stroke test:
• to pneumatically actuate the valve drive by means of the valve device, so that the valve drive sets the valve member in a test movement sequence in which the valve member performs a first test movement from a first position to a second position and a second test movement from the second position back to the first position,
• to detect pressure information related to the pneumatic actuation of the valve drive and, taking the pressure information into account, to determine status information indicating the functioning and/or wear of the process valve apparatus,
• wherein the control device is configured to control the valve device, in the partial stroke test prior to the first test movement, with a first preparation control signal value to cause the drive pressure to change at a first preparation rate of change toward a first preparation drive pressure value, and upon reaching the first preparation drive pressure value, to control the valve device with a first control signal value, to cause the drive pressure to change at a first safety rate of change toward a first breakaway pressure value at which the first test movement begins, wherein the magnitude of the first preparatory control signal value is greater than the magnitude of the first control signal value such that the magnitude of the preparatory rate of change is greater than the magnitude of the safety rate of change.