Patent ID: 7380293

Claim:
A safety valve for halting water flow to a filling valve of a toilet tank in the event of failure, the valve comprising: a valve body; an inlet connector in the valve body for inlet of water from a water supply pipe at a supply pipe pressure; an outlet connector in the valve body for connection to a filling line of a toilet tank; a water supply duct within the valve body for passage of water from the inlet connector to the outlet connector; a valve seat in the supply duct; a valve member for movable between a closed position against the valve seat to prevent flow of the water from the inlet connector to the outlet connector and an open position spaced from the valve seat to allow flow; a piston connected to the valve member for moving the valve member; the piston being mounted in a cylinder in the valve body having a first chamber on one side of the piston and a second chamber on the other side of the piston; the piston being movable within the cylinder from a first end in which the valve member is open to a second end in which the valve member is closed; a pressure reduction orifice in the supply duct in the valve body through which the water flows as it passes from the inlet connector to the outlet connector having an orifice arranged so as to provide in a low pressure chamber of the pressure reduction orifice a water pressure lower than the supply pipe pressure; a first transfer duct in the valve body for transferring water at the supply pipe pressure from the water supply duct to the first end of the cylinder; a second transfer duct in the valve body for connecting second end of the cylinder to the low pressure chamber; such that a pressure difference across the piston caused by the difference in pressure between the supply pressure and the low pressure chamber causes the piston to move from the first end toward the second end; a flow control orifice in one of the first and second transfer ducts for regulating a rate of flow of water therethrough such that a time of movement of the piston from the first end to the second end in which the valve member is closed is greater than an expected time required to fill the toilet tank; and a spring biasing the piston to the first end for returning the piston to the first end after the toilet tank is filled, when there is no pressure difference across the piston; whereby, in the event that the tank is filled and the filling valve closed before the valve member is closed by the movement of the piston, the piston is moved back to the first end; and whereby, in the event the filling valve remains open for a time longer than said time of movement, the valve member is closed by the movement of the piston to prevent further supply of water to the filling valve.