Method and apparatus for measuring specific gravity of a flowing liquid

摘要

A method and apparatus for continually measuring the specific gravity of a flow liquid. The liquid is caused to flow across a flat measurement surface defined by a light transmissive shelf member. The measurement surface, i.e. the interface between the shelf member and liquid sample thereon, is illuminated by rays incident at angles greater than and less than a critical angle to reflect a boundary line whose position is dependent on the critical angle and thus the specific gravity of the liquid sample. The reflected boundary line is projected onto a photovoltaic surface which, together with detector electronics, determines the position of the boundary line with respect to a boundary line position associated with a reference liquid. The difference in boundary line position is used by the detector electronics to determine the specific gravity of the sample by a table lookup procedure.