Liquid level sensing method and apparatus

Claim 1

An automated liquid holding tank, comprising: a tank for holding liquids; fill means for dispensing one or more liquids into said tank; liquid level measurement means being engaged to said tank and functioning to provide an output signal indicative of the level of liquid within said tank, said liquid level measurement means comprising a pressure sensitive device that is engaged proximate a bottom surface of said tank to measure the hydrostatic pressure of the liquid within said tank as a measure of the liquid level within said tank, said pressure sensitive detector being engaged to said tank utilizing a length of hollow tubing, and wherein a gas bubble is disposed within portions of said hollow tubing proximate said pressure detector; controller means operative to initiate and terminate said dispensing of said one or more liquid components into said tank, said controller means having a memory storage and a comparison means, said memory storage being adapted for storing a liquid level set point value for each said liquid dispensed into said tank, said comparison means being provided to compare said output signal to said liquid level set point values; control means being engaged to said fill means and functioning to control said fill means in response to a signal from said controller means; said controller means providing a signal to said control means when said output signal is approximately equal to a liquid level set point value stored in said memory storage.