Abstract: A wedge type gate valve in which a pressure equalizing valve is located in a chamber in the wedge-shaped valve member which is vented to the downstream side of the gate to equalize system pressure prior to opening the valve by using a ball-valve rotationally mounted in chamber. The ball-shaped valve is operated by the stem which operates the gate-valve for limited rotational movement between two stops of a connecting member in such a way that the stem rotational movement is stopped at a predetermined point when the sealed internal ball-shaped valve is fully opened or fully closed, thereby opening or closing the wedge-shaped member pressure equalizing passage. The vent passage which opens from the pressure equalizing valve chamber to the downstream side of the gate also permits the evacuation of fluids from the annular space above the gate.

Abstract: In a gate valve which has a pressure equalizing valve located in a chamber formed in its valve member, there is provided a vent passage opening from an expansion compartment which is located above the pressure equalizing valve, through the downstream side of the valve member such that any pressure buildup in the expansion compartment resulting from the opening of the pressure equalizing valve may be vented to the downstream side of the valve member and will not cause the pressure equalizing valve to move to its closed position.