Donald G Atkins

US Patent:

46008446, Jul 15, 1986

Filed:

Jun 7, 1984

Appl. No.:

6/617957

Inventors:

Donald G. Atkins - Cedar MN

Assignee:

The Marley-Wylain Company - Mission Woods KS

International Classification:

H01H 3518

US Classification:

307118

Abstract:

A circuit for controlling the level of a liquid in a tank between predetermined limits is disclosed. A low and high probe are provided, each connected in the tank at the desired limit levels, and each connected to a comparator associated therewith. The output of each of the comparators are connected as inputs to an OR gate, which provides the control signal for activating a pump to pump liquid from the tank, and further provides a latching signal to the lower limit comparator, to keep that comparator latched in an off position until the upper limit comparator is triggered by liquid coming into contact with the upper limit probe. Once activated, the upper limit comparator causes the OR gate to produce a pump activation signal, in addition to unlatching the lower limit comparator, which in turn produces an OR gate activating signal which remains set until the pump evacuates the tank below the level of the lower limit probe, thereby deactivating the OR gate and the pump and whereby the process may be reinitiated.