The application discloses a valve, which may include either a safety valve or a storm surge choke valve or the like, to isolate a zone below a valve from a string of production tubing. Preferably, the valve includes a flow interruption surface assembly, such as a flapper valve or a ball valve, displaced by an operating conduit extending from a surface location to the valve through the inside of the production tubing. The application also discloses a bypass-conduit inside the production tubing to allow communication from a surface location to the production zone when the valve is in either an open or a closed location.