Abstract: A high vacuum valve assembly comprising a valve body with an air chamber formed therein. A gate unit is disposed within the air chamber and includes a valve gate portion disposed to mate to a valve seat, the valve gate portion and the valve seat portion each being disposed at the same angle to provide increased sealing force. The gate unit is urged into closure against the valve seat by a first tension source, which may be a spring, and away from the valve seat by a second tension source, which may be compressed gas, such that the gate unit comprises the only moving part of the valve.