Patent ID: 6837263

Claim:
A liquid level control system comprising: a tank; a source of liquid in communication with said tank; a pressure fluid actuated valve for controlling the flow of liquid to said tank from said source; a hydrostatic pressure sensor disposed in said tank, said pressure sensor including a conduit having one end submersed in the liquid in said tank; a source of pressure fluid; and a pressure fluid amplifier having separate connections for each of a pressure fluid outlet coupled to the pressure fluid actuated valve for controlling the flow of liquid from said source of liquid, a first inlet coupled to said source of pressure fluid, and a second inlet in communication with an other end of the conduit of said sensor, said amplifier including a proportional sensor for providing selective communication between the source of pressure fluid and said pressure fluid actuated valve, the proportional sensor directly responsive to proportional changes in pressure within said amplifier due to one of a flow of pressure fluid in said amplifier and a level of liquid in said tank, wherein a predetermined level of liquid attained in said tank is determined by a flexibility of the proportional sensor.