Conductivity electrodes are devices that measure the salinity and conductivity of water samples. Conductivity is simply a measurement of how well a material carries a current. An electrode is inserted into a sample liquid to determine the concentration of ions. Because electrode size differs between devices, conductivity is measured in Siemens/unit area of the electrodes. Conductivity electrodes are not stand-alone units and thus require external signal analysis or data acquisition equipment.
Critical specifications for conductivity electrodes are conductivity range, accuracy, response time and cell constant. Cell constants define the volume between the electrodes. Cell constant K is directly proportional to the distance separating the 2 conductive plates and inversely proportional to their surface area. K= d/a. Cell constants should be matched to the meter or controller for the expected range of operation. Different cell constants act like mechanical multipliers for a solution's resistance.
A number of mounting options are available for conductivity electrodes. A handheld or “dip” style device is popular for laboratory work, as it is easy to use, not requiring special mounting and is often portable. In-line or insertion styles are good for direct measurement without disturbing line flow, as they can be inserted directly through a pipe or bulkhead. Flow-through types of electrodes typically come with integral flanges or other means of pipe connection to be placed directly into existing pipeline.
Typical features of conductivity electrodes include water resistance, temperature compensation, built-in temperature sensor and a design specially suited for sanitary applications. One special feature is an output of total dissolved solids (TDS). Electrolytes such as acids, bases or salts will increase the conductance of water and other liquids. Thus, conductivity can be used to measure the total dissolved solids in closed water systems such as boilers and cooling towers.Read user Insights about Conductivity Electrodes