Patent ID: 8387710

Claim:
A downhole valve for insertion in a production tubing string and a casing string, wherein an annular space is defined between the tubing and the casing, said valve comprising: (a) a cylindrical housing defining an opening; (b) an internal mandrel disposed within the housing, defining a central bore and defining an opening; (c) a valve disposed between the housing and the mandrel, wherein said valve is actuated by fluid pressure in the annular space which is greater than fluid pressure in the mandrel bore to move between a closed position which prevents fluid communication from the annular space to the mandrel central bore through the housing opening and the mandrel opening, and an open position which allows fluid communication from the annular space to the mandrel central bore through the housing opening and the mandrel opening; and (d) a spring for biasing the valve in the closed position, wherein the spring comprises a coil spring concentrically disposed within the housing, and around the mandrel.