A rotary valve (also called rotary-motion valve) is a type of valve in which the rotation of a passage or passages in a transverse plug regulates the flow of liquid or gas through the attached pipes. The common stopcock is the simplest form of rotary valve.The rotary control valve is a directional control valve actuated in a rotary motion. With high pressure and zero-leak performance, the valve is designed and manufactured to meet your requirements for both topside and subsea applications.They are most often used in air conveyor systems to minimize the loss of pressure across the valve, but rotary valves are also used to meter materials at a controlled feed rate. They work almost exclusively in air systems and function as airlocks, explosion/flame barriers, and process isolators, among other tasks.