Abstract: An apparatus and process for making noncontact measurements of liquid conductivity are disclosed. This apparatus forms a conductivity cell and uses two toroids, one to generate a magnetic field and another to sense the magnetic field, placed in an enclosure which allows liquid to pass through it for measurement. Ground planes constructed preferably of printed circuit boards with conductive layers are used to reduce capacitive coupling between the toroids and provide better shielding. Circuitry on or near these circuit boards are used to convert local, low level signals from a sensing toroid to signals which can be more readily passed to and from a recording system or operator without degradation. Sensors on or near these circuit boards can be used to sense environmental conditions in order to improve operation and stability of the conductivity cell. Methods and apparatus for increasing circuit sensitivity and calibrating the sensor are also disclosed.

Abstract: An apparatus and process for making noncontact measurements of liquid conductivity are disclosed. This apparatus forms a conductivity cell and uses two toroids, one to generate a magnetic field and another to sense the magnetic field, placed in an enclosure which allows liquid to pass through it for measurement. Ground planes constructed preferably of printed circuit boards with conductive layers are used to reduce capacitive coupling between the toroids and provide better shielding. Circuitry on or near these circuit boards are used to convert local, low level signals from a sensing toroid to signals which can be more readily passed to and from a recording system or operator without degradation. Sensors on or near these circuit boards can be used to sense environmental conditions in order to improve operation and stability of the conductivity cell. Methods and apparatus for increasing circuit sensitivity and calibrating the sensor are also disclosed.