Patent ID: 8746060

Claim:
A method of improving the accuracy of an electrode based wastewater liquid level indicator intended to operate in a fat, oil, grease and other waste (FOG contaminant) wastewater environment, said electrode based liquid level indicator comprising: a wastewater liquid level measuring device intended to be at least partially immersed in a liquid waste container, said liquid level measuring device comprising a non-conductive surface with a plurality of electrodes disposed on said surface so that said electrodes are suspended at different depths in said liquid waste container; wherein in the absence of said FOG contaminant, the level of the liquid in said liquid waste container is measured by correlating the electrical interactions between said plurality of electrodes and an electrical reference in said liquid, and wherein in the presence of said FOG contaminant, said FOG contaminants variably adhere to said measuring device and distort said electrical interactions, thereby causing inaccuracy in said measurement; said method comprising: using information on the distorting effect of said FOG contaminant on said electrical interactions to construct a FOG effect algorithm; obtaining at least one measurement of the electrical interactions between said plurality of electrodes and said liquid; and using said FOG effect algorithm to correct for the distorting effect of said FOG contaminant on said electrical interactions, thereby producing FOG corrected measurements, and improving the accuracy of said electrode based liquid level indicator; wherein said electrical interactions between said plurality of electrodes and said liquid are monitored periodically as a function of time; wherein the distorting effect of said FOG contaminant on said electrical interactions between said plurality of electrodes and said liquid is such that at least a FOG partial water bridge is formed between at least two adjacent electrodes on said liquid measuring device, one adjacent electrode being an upper electrode mounted on a higher level in said measuring device, and one adjacent electrode being a lower electrode mounted on a lower level in said measuring device; wherein when said lower electrode and said upper electrode are initially dry, and said liquid level in said container rises to make electrical contact with said lower electrode at time T1, said FOG partial water bridge causes said upper electrode to make premature electrical contact with said liquid at later time T2; using said FOG effect algorithm to determine if the difference time T2−T1 is within one or more FOG partial water bridge time parameters, and if so generating a FOG alarm signal and/or correcting said measurement for the presence of FOG contaminants.