Liquid shut-off valve

A float-actuated valve for shutting off high flow rates of liquid fed into a tank comprising, in combination:

• a) a valve body having an inlet and an outlet joined by a first bore aligned co-axially with the feed pipe through which the liquid is fed to the tank;
• and,
• b) a valve spool rotatably mounted in a cross-bore formed in said valve body, between said inlet and said outlet, and attached to a float spaced outward from said valve body that is responsive to the level of liquid in the tank;
• c) said spool having formed therethrough a second bore terminated by an inlet and an outlet, creating an upstream second bore first wall and a downstream second bore second wall on the respective sides of said second bore in said spool for containing the flow of liquid passing therethrough, for rotation by said float from a first position in general alignment with said first bore, to allow passage of large volumes of liquid therethrough, through a series of intermediate positions, where the flow is progressively reduced by the respective leading edges of said second bore first and second walls moving into the path of the flowing liquid, to a second position where said second bore is in full non-alignment with said first bore to totally shut off the flow of liquid;
• d) said valve including relief means associated with said downstream second bore second wall of said spool to reduce the pressure of the flow, during rotation of said spool through said series of intermediate positions, to counteract the hydraulic turning moment developed by the large flow of liquid tending to hold the valve open against the action of said float when said spool is rotated to said second position.