US 7,581,437 B2 · Level sensor for granules in water

Abstract

The present invention relates to a system for measuring the level of granular material in a container immersed in an aqueous medium, particularly, but not exclusively, for use as a measure of sanitizer level in spa and whirlpool halogenation systems. Electrodes fixed in the container wall are used to measure the electrical conductance along a path which is part filled with the granular material. Coils of wire are arranged such that the interrogating signal is coupled inductively to the sensor head. In this way the granule container can be made demountable, with no bare conductor material exposed to the aqueous medium. A separate reference circuit is used to measure the conductivity of the water in the system, and this signal is used to normalize the signal obtained from inside the container.

Claims17

Dependent claims

An apparatus for measuring fill level of a cartridge containing granules or powder of a non-insulating material, in an aqueous environment, comprising:

a cartridge;
a plurality of electrodes on the inside of the cartridge;
an alternating current impedance measuring circuit attached to the electrodes for measuring a cartridge impedance of the cartridge;
a plurality of reference electrodes in the aqueous environment around the cartridge;
and
a reference circuit attached to the plurality of reference electrodes for measuring a reference impedance of the aqueous environment around the cartridge, such that the fill level of the granules or powder is determined from a ratio of the cartridge impedance to the reference impedance.

3 more elements

Dependencies are inferred from the claim text.

Level sensor for granules in water

Life of this patent

Level sensor for granules in water

Life of this patent

Abstract

Claims17