What is the “normal” or expected life of your pH and ORP (redox) sensors?
The pH and ORP measuring electrode (center) part of the sensors are glass and platinum respectively and can have very long life as long as they are not broken or chemically attacked. pH glass electrodes are attacked by hot caustic solutions and will gradually lose response over weeks or months, depending on the severity of conditions above 10 pH and/or above 60 degC. pH glass electrodes can also be attacked and destroyed by hydrofluoric acid over hours or days depending on the severity of fluoride concentration above 5 ppm and pH lower than 4. General purpose pH and ORP sensors also include a reference electrode which has a finite amount of electrolyte. The electrolyte salts must maintain consistent electrical contact with the process sample though the reference junction (surrounding the measuring electrode) to allow measurement. Because of this contact, it is subject to gradual dissolving and loss in the sample, although this is retarded by a thick gelling agent. Reference electrode l
