Conductivity electrodes for field conductivity and salinity measurements.
The TetraCon® 4-electrode conductivity cells set a new standard for professional conductivity measurements. In comparison with conventional measuring cells with 2 electrodes, the TetraCon® 325 conductivity cell offers numerous technical advantages. The conductivity electrode was designed to optimize the conductivity cell geometry providing you with the highest accuracy electrode possible. The conductivity cell's design allows it to have an extremely large measuring range using a single electrode and meter combination for most applications. Long-term cell constant stability is a result of the conductivity cell's high-quality abrasion-resistant graphite electrode construction. The conductivity cell's design also allows for a very shallow immersion depth, 1.4 inches (36 mm), with a virtually unbreakable robust epoxy body. Additional design features mean that the conductivity cell's measurements are not affected by cable influences, polarization effects or contact with any surfaces. All TetraCon® 4-electrode conductivity cells come with a built-in temperature sensor to automatically compensate the output to your sample's temperature. The automatic resistance compensation feature provides you with accurate measurements even with a dirty conductivity cell.
Conductivity cell measurements
Conductivity is a parameter used to measure the ionic concentration and activity of a solution. The more salt, acid or alkali in a solution, the greater its conductivity. The unit of conductivity is S/m, often also S/cm. The scale for aqueous solutions begins with pure water at a conductivity of 0.05 uS/cm (77 °F /25 °C). Naturally occurring waters such as drinking water or surface water have a conductivity in the range 100 - 1000 uS/cm. At the upper end of the chart some acids and alkalines can be found.
Conductivity cell measurements are used for a wide range of applications such as the production of ultrapure water or determining the salinity of sea water.
Conductivity is measured by using a conductivity cell to make a measurement of the electrical resistance. The simplest kind of measuring cell used consists of two similar electrodes. An alternating voltage applied to one of the conductivity electrodes causes the ions in the solution to migrate towards the electrodes. The more ions in the solution, the greater the current which flows between the conductivity electrodes. The conductivity meter measures the current produced by the conductivity cell and uses Ohm's law to calculate first the conductance of the solution and then - by taking the cell data into account - the conductivity.