Electrolyte Contamination The contamination of the reference half cell is linked to the diffusion of external substances into the reference chamber (strong oxidants, reductants, complexing agents). The combination of Hanna double junction technology with a polymer reference electrolyte, reduces the diffusion process rate and keeps the reference potential stable for long periods of time. Dilution When the reference cell containing concentrated 3.5M KCl electrolyte comes in contact with a less concentrated aqueous sample, diffusion of the electrolyte into the sample will occur. This process causes a progressive dilution of the reference electrolyte with a consequent variation of the reference potential. Hanna double junction technology and the use of a large electrolyte volume (up to three times greater than traditional electrodes) makes this dilution effect negligible. Electrochemical Reaction In many industrial applications, it is possible to get a potential difference between the measuring point and the instrument. This inconvenience originates from electrical currents that destroy the Ag/AgCl element of the reference half-cell and also creates non-stable, interfering potentials. Hanna’s simple and effective solution to this challenge is the matching pin built-in to each industrial electrode. The matching pin is a stainless steel or titanium element that is connected to the instrument to prevent grounding problems, and to prolong electrode life. Junction Clogging Typical industrial applications require continuous monitoring of pH and ORP. Periodic cleaning and maintenance of the electrode junction ensure a stable and repeatable contact between sample and junction. The frequency of these cleaning procedures depends on the shape of the junction and material. Hanna industrial electrodes are provided with different types of junctions. In particular, the porous PTFE junction used for the flat tip electrodes, which can provide optimum performance for months without requiring any maintenance. Measurement Half Cell All Hanna industrial pH electrodes include a measurement cell with a glass sensor. A glass sensor is the only answer for most industrial requirements. Below is a list of the main causes of shortened glass sensor life, for which Hanna has developed different types of specialized glass: • High temperature • Low temperature • Acid samples containing fluoride Electrodes Designed and Manufactured by Hanna Process Electrodes 15 Process Instrumentation 15.113 www.hannainst.com | electrodes
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