Liquid level control

Claim 1

A liquid level control for activating a pump when the liquid reaches an upper level and for deactivating a pump when the liquid reaches a lower level comprising: means responsive to the liquid level for controlling a first switch in a relay power supply circuit such that the switch closes when the upper liquid level is reached and remains closed until the liquid level recedes below the upper liquid level, said switch means comprising an inverted conduit enclosed at the upper end and extending below the upper liquid level but not below the lower liquid level; means above the upper liquid level responsive to the pressure in the pump''s discharge pipe for controlling a second switch in said relay supply circuit such that the switch closes when the pump begins to force liquid into the discharge pipe and remains closed until the pressure in the discharge pipe falls at the lower level, said first and second switches being connected in parallel, said relay switch controlling the electrical power to said pump whereby the first switch activates the relay and the pump, at least for a time sufficient to raise the pressure in the discahrge pipe to activate the second switch and the relay and the second switch maintains the relay closed until the pressure in the discharge pipe lowers due to the decrease in the liquid level.