Patent ID: 6683464
Filing Date: 2004-01-27
Classification: G01F,G01N

Abstract:
A stabilized fluid conductivity measurement system comprising:a threaded metal housing for mounting into a container for fluids, said fluid having conductivity to be measured; said housing having an inner portion to extend into the fluid, and an outer portion; first and second probes or electrodes; insulative support arrangements mounted on the inner portion of said housing to support said probes or electrodes in spaced relationship to each other; circuitry coupled to said probes mounted within the outer portion of said housing; said circuitry including a modified Wheatstone bridge circuit having first and second input excitation terminals and first and second output terminals; a source of balanced square wave signals coupled to said input excitation terminals; an additional fixed resistance coupled between said first input and said first output terminals, and another fixed resistance coupled between said first output terminal and said second input terminal; fixed resistance coupled between said first input terminal and said second output terminal; resistive circuitry having an intermediate tap, mounted between said second output terminal and said second input terminal; the first of said probes being connected to said tap; and the second of said probes being connected to said first input terminal.