A single line surface controlled, subsurface safety valve, adapted for connection in a well tubing string. The safety valve has a closure means disposed in the bore of the safety valve housing and is operable by action of control pressure fluid causing a longitudinal operator to move the closure means to an open to flow position. MULTI-FUNCTIONAL WATER PUMP CONTROL VALVEThe control pressure fluid chamber in the safety valve is protected from well pressure by providing annular areas, between the longitudinal operator and the housing, positioned between the control pressure fluid chamber and well pressure.API Cast Steel Valves The annular areas are sealed from exposure to well pressure and are in fluid communication with each other. A floating piston is positioned to respond to well pressure entering the annular areas and thus move to engage and assist the operator means in closing the safety valve to flow of well fluids therethrough.Safety Valves Vent means is provided to prevent a hydraulic lock from retarding movement of the floating piston. When properly installed as part of a subsurface safety system in a well, safety valves are designed to automatically shut-in a well below the earth's surface in the event of erratic changes in flowline pressures, damage to the wellhead or malfunction of surface equipment. Safety valves are designed to be either installed in a tubing string or made up as part of the tubing string. Regardless of the manner in which they are installed in a well installation, they are designed to close on demand from the surface of the well, providing the well operator with complete control of the valve's operation. Another feature of the illustrated safety valves is that they are operated by a single pressure fluid line extending from the valve to a source of pressure fluid at the surface of the well. The pressure fluid arriving at the valve enters a variable capacity pressure chamber which expands upon an increase in pressure transmitted to the valve from the surface of the well. The variable capacity pressure chamber is usually housed in an annular area located between the safety valve housing and an inner, longitudinally movable tubular sleeve. This sleeve, when moved downward operates to open a closure device allowing well fluids to flow through the safety valve. The sleeve noramlly is biased by a spring or some other resilient urging means so that upon release of pressure in the variable capacity pressure chamber, the sleeve is moved back to its first position, allowing the closure device to return to its closed-to-flow position. Thus, in order to accomplish its " safety" function, the valve must be able to close upon release of pressure in the variable capacity pressure chamber. The pressure chamber is normally isolated from well pressure by O-ring or other types of seals being placed so as to seal off an area in the annular space between the operator sleeve and the safety valve housing. In the event a seal fails, well pressure can enter the pressure chamber. If the well pressure exceeds the spring force required to close the safety valve, the well cannot be closed to flow. Also, well pressure can invade the conduit used to transmit pressure fluid to the valve, causing a blowout through the conduit.

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