Conductivity sensor

Abstract

A conductivity sensor is described in which electrodes are held in a desired position within a housing of the sensor by a number of slots accurately positioned within the housing. In one embodiment the slots are integrally formed within the housing. Once the electrodes have been inserted into the slots a thermoset resin is poured into the housing and cured. A through bore is then drilled through the housing, the electrodes and the cured resin to form a flow conduit through the sensor. A dual frequency excitation technique is also described that allows a measurement to be obtained of a polarisation resistance of the electrodes. In one embodiment this measurement is stored and used to correct subsequent conductivity measurements.

1 .- 51 . (canceled) 
     
     
         52 . A conductivity sensor comprising:
 a housing defining a flow conduit for the passage of a fluid;   first and second electrodes spaced apart along said flow conduit;   excitation circuitry operable to connect to said electrodes and operable to generate excitation signals; and   processing circuitry operable to connect to said electrodes and operable to determine conductivity measurements of fluid flowing through the housing;   wherein at least a part of said excitation and said processing circuitry is mounted on a circuit board that is connected to said electrodes by first and second edge connectors that are each directly attached to said circuit board and to an edge of a respective one of said first and second electrodes and wherein said edge connectors comprise one or more barbs for gripping the edge of the electrode when inserted into the connector.   
     
     
         53 . The conductivity sensor according to  claim 52 , wherein said electrodes have a rectangular block shape and said edge connectors are arranged to attach to a minor edge of the respective electrode.