What is a toroidal (inductive) conductivity sensor and when is it preferred?

Toroidal conductivity sensors use electromagnetic induction: a drive coil generates alternating magnetic field that induces current flow in the conductive liquid, which is measured by a receive coil. Current is proportional to conductivity. Advantages over contacting sensors: no electrode fouling (non-contact with process), suitable for high conductivity (>100 uS/cm), corrosive chemicals, and coating/scaling environments. Applications: chemical processes, wastewater, CIP systems, and slurries. Considerations: larger sensor size, minimum conductivity requirement (~50 uS/cm), and installation position for complete immersion.