Actuator for dual drill string valve and rotary drill string valve configuration therefor

A dual drill string valve, comprising:

• an actuator comprising;
• a piston disposed in a housing, the housing configured to sealingly couple at its longitudinal ends to an end of a nested dual drill string segment, an upper internal conduit mounted in the housing proximate one longitudinal end thereof,
• a lower internal conduit mounted in the housing proximate the other longitudinal end thereof, the piston slidably, sealingly engaged between the upper and lower inner conduits and defining an internal fluid flow passage therethrough, and wherein the upper inner conduit, the piston and the lower inner conduit define an external flow passage between respective exterior surfaces thereof and an interior of the housing such that application of fluid pressure to the external flow passage causes movement of the piston away from the upper inner conduit;
• and
• a rotary valve coupled to the actuator such that movement of the piston longitudinally causes rotation of the rotary valve.