It is not necessary to put the instrument in water to test it. It will not hurt the conductivity cell to be in air. If there is a pump on the instrument, it should not be run for extended periods in air. Profiling instruments (SBE 9plus, 19, 19plus, 19plus V2, 25, 25plus, 49, GPCTD) and some moored instruments (all pumped MicroCATs with integral dissolved oxygen (DO), pumped MicroCATs without DO with firmware 3.0 and later, and all HydroCATs and HydroCAT-EPs) do not turn on the pump unless the conductivity frequency is above a specified minimum value (minimum value is hard-wired in 9plus, user-programmable in other instruments). This prevents the pump from turning on in air. See the instrument manual for details. If your instrument does not check for conductivity frequency before turning on the pump:  - For moored SeaCATs (16, 16plus, 16plus-IM, 16plus V2, 16plus-IM V2): Disconnect the pump cable for the test.  - For older pumped MicroCATs: orient the MicroCAT to provide an upright U-shape for the plumbing. Then fill the inside of the pump head with water via the pump exhaust tubing; this will provide enough lubrication to prevent pump damage during brief testing.