Abstract: A system and method for controlling fluid according to which an inlet passage and an outlet passage are formed in a housing and a choke member is movable in the housing to control the flow of fluid from the inlet passage to the outlet passage and to exert a back pressure on the fluid. The movement of the choke member from a fully closed position to an open position is dampened.

Abstract: A back pressure control choke operates to automatically control and maintain a desired back pressure on the fluid passing through the choke. The choke housing has an inlet channel which intersects with an axial bore, part of which bore constitutes the discharge channel. An annular choke seat concentrically arranged in the discharge channel of the axial bore is adapted to receive an annular choke element. The choke element is affixed to a shuttle which is mounted on a fixed mandrel extending into the axial bore of the choke housing. The shuttle is dynamically sealed against the housing and mandrel such that a closed chamber is created in that portion of the axial bore opposite the discharge channel. The shuttle element is constructed to be fluid balanced such that it will move to achieve an equilibrium of pressure on its forward and rear surfaces.