How is the conductivity cell affected by objects in close proximity?

Based on laboratory experiments at RBR, accuracy of the conductivity measurement is affected by objects within 15cm of the inductive cell, especially if these objects are conductive. Metal deployment frames are a good example. This proximity effect decreases with distance. 

See Proximity effects on conductivity measurements for more details.

RBR routinely calibrates the instruments built with sensor guards and cages, negating the effect of these permanent objects on the inductive cell.  When static objects (such as other sensors, guards or cages) are included in the conductivity calibration, the achieved calibration is always within the specified accuracy of ±0.003mS/cm.