Profile: Cornerstone Controls, Inc. specializes in the installation and service of DDC direct digital control systems. Our product line includes control systems, control valves, on/off valves & valve automation. regulators, solenoid valves and flow computers. Our control valves includes actuators, control valves, digital valve controllers and positioners. Our electric actuator provides a stem force output for a variety of process applications by using electricity as the power source. Our Fisher® 1051 pneumatic actuators provides high stem force output for demanding service conditions. These actuators are usually air operated but some can be self operated by the process fluid.