US Patent 7658366 High-pressure bi-directional valve

A control element of a bi-directional valve is in fluid communication with an outlet pressure and an inlet pressure when the valve is closed such that a sum of the forces applied to the control element result in a net force urging the control element to seat against a valve seat. The valve includes a valve body carrying the valve seat. The control element is balanced on an outlet side of the valve seat such that the outlet pressure applies approximately no net force to the control element. In contrast, the control element is unbalanced on an inlet side of the valve seat such that inlet pressure applies a net force on the control element to bias the control to seat against the valve seat.