Patent ID: 7213457

Claim:
A method for determining the water level in a boiler steam drum, heater, or other piping or pressure vessel, comprising the steps of: projecting a first light from a first array of light emitting diodes of a first colour; projecting a second light from a second array of light emitting diodes of a second colour, said light emitting diodes being arranged such that said first and second lights can be projected at various positions; passing said first and second lights through a heat divider; passing said first and second lights through a column containing steam and water at a varying level to an opposing side of said column relative to said light emitting diodes, said heat divider separating said light emitting diodes from high temperatures existing at said column; observing the respective positions of the first and second lights as projected and passed through said column at varying vertical levels; and determining the presence of water or steam at each of said varying vertical levels based upon the observed position of either of the first or the second lights at said varying vertical levels.