Pumping system with air vent

Claim 1

A pumping system for pumping liquid comprising: a housing having an inlet and an outlet, said inlet being connectible to a source of liquid; a pump having a suction opening and a discharge opening, said pump being mounted in said housing for pumping liquid through said housing from said inlet to said outlet; wall means on said housing defining a float chamber in communication with the discharge opening of said pump, said wall means having a vent opening therein in communication with the exterior of said housing; means for blocking said float chamber from direct communication with the suction opening of said pump whereby the only flow path between said float chamber and the suction opening is through the discharge opening; a float in said float chamber movable in response to the liquid level in said float chamber; a valve including a valve element movable between a closed position in which the valve element closes the vent opening and an open position in which the valve element allows flow through the vent opening; said valve element being drivable toward at least one of said positions thereof by said float, said valve element closing said vent opening in response to a relatively high liquid level in said chamber and opening said vent opening in response to a lower liquid level in said chamber; and said vent opening being a first vent opening, said valve including a first valve element and a stem, said stem projecting through said first vent opening in both the open and closed positions, means defining a second vent opening in series with the first vent opening, a second valve element disconnected from said stem for closing the second vent opening, said second valve element including a disc.