Temperature and pressure resistant shutoff valve

摘要

The float-controlled shutoff valve has an upright flow passage controlled by a transverse valve spool rotated between open and closed positions by the float in response to changing levels of liquid within the holding tank. The spool has a deep, generally U-shaped, diametrically extending cavity on one side and a single, solid sidewall on the opposite side, the cavity being so formed that it presents a cross-flow inlet approximately one quarter turn away from the passage blocking surface of the sidewall. Hence, when the spool is in its open position during filling, the cavity is vertically flow-aligned with the passage while the blocking sidewall is disposed alongside the passage, and when the spool is in its closed position the blocking sidewall spans the passage above the horizontally disposed cavity to prevent fluid movement past the spool. As the spool leaves its open position and commences progressive rotation toward its closed position, the large void area of the cavity and its lack of sidewall structure in opposition to the blocking sidewall avoids the presentation of a deflecting or impinging surface against which the flow can bear as it moves through the spool, thus avoiding the creation of a countervailing force tending to reopen the valve. Special geometric relationships between the valve body and the spool, as well as a special manner of journaling the spool for rotation relative to the body, minimize leakage past the spool itself and at the journal points, while also promoting rapid filling.