Apparatus for determining the position of a rotary valve

A position indicator for indicating the position of a rotary valve actuator output shaft which is connected to a valve shaft for being rotatable about an axis in an actuator housing between an open position at which fluid flow through the valve is enabled and a closed position at which fluid flow through the valve is disabled, comprising,

• a stator having a cylindrical wall with a central axis, and means for fixedly mounting the stator on the actuator housing in axial alignment with the actuator output shaft,
• a rotor having an inner cylindrical wall, a coaxial outer cylindrical wall, there being a cylindrical space between said rotor inner cylindrical wall and said rotor outer cylindrical wall, and an end wall connecting the rotor inner cylindrical wall and rotor outer cylindrical wall, the rotor being rotatably mounted on the stator with the rotor end wall transverse to the stator axis, the rotor inner cylindrical wall intermediate the stator axis and stator cylindrical wall and the stator cylindrical wall in the space intermediate the rotor inner cylindrical wall and rotor outer cylindrical wall, the rotor further having connecting means for fixing the rotor to the actuator output shaft in coaxial relationship therewith,
• the stator cylindrical wall having an opening forming a first stator window,
• the rotor outer cylindrical wall having an opening forming a first rotor window which is in registration with the first stator window for obscuring the stator cylindrical wall and exposing the rotor inner cylindrical wall when the actuator output shaft is in one of the open and closed positions and the first rotor window being out of registration with the first stator window for exposing the stator cylindrical wall and obscuring the rotor inner cylindrical wall when the actuator output shaft is in the other of the open and closed positions.