Capacitance probe and spacer therefor

Abstract

A capacitance probe including a spacer for separating an inner conductor from an outer conductor. The spacer has a member that substantially surrounds the outer conductor and includes a number of spacing elements that extend inwardly through apertures in the outer conductor to position the inner conductor concentrically with the outer conductor. The spacers advantageously are installable from the outside of the outer conductor through apertures in the outer conductor to simplify production of the capacitance probe. The spacers also allow material to fill and drain easily between the conductors, and allow more of the material being measured to make contact with the conductors improving linearity and gain of capacitance measurement. Additional features contributing to the low cost manufacturability of the probe include ability to use conventional materials, such as longitudinal seam stainless steel tubing for the inner and outer conductors, inner conductor insulation fabricated from conventional heat shrink tubing, a relatively simple fitting including a single O-ring for coupling both the inner and outer conductors to the housing.