Patent ID: 8768631

Claim:
A method of determining a source of a leak in a pneumatic control valve actuator comprising: sensing travel of an actuator rod, the actuator rod being coupled to an actuator of the control valve; sensing a pressure applied to a chamber of the actuator; transmitting to a processor the sensed travel and the sensed pressure; determining in the processor the existence of an actuator gas leak based on the sensed travel and the sensed pressure; if the processor determines the existence of a gas leak, determining with the processor whether a flow switch coupled to an actuator vent indicates venting of exhaust gas through the actuator vent; if the processor determines that the flow switch indicates no venting of exhaust gas, generating, via the processor, an indication of a pneumatic tubing leak; and if the processor determines that the flow switch indicates venting of exhaust gas and the control valve is sensed to be moving, then generating, via the processor, an indication of an actuator diaphragm failure.