Reference electrode for ion-activity measurement, in particular for pH measurement

摘要

A reference electrode, in particular for a pH-measuring cell, for connecting to an electrical instrument with a measuring amplifier inserted in between, an additional measuring electrode being connected to the measuring amplifier. Known electrodes of this type are usually sensitive to contaminants and not resistant to elevated temperatures and pressures or to acidic and alkaline solutions. In the case of the reference electrode according to the invention, resistance to high pressure and high temperatures and to the abovementioned solutions is achieved by providing a glass tube whose lower end is sealed by a stopper composed of porous ceramic. The glass tube is filled with an electrolyte and contains a chlorinated silver wire which is immersed in the electrolyte and connected to a connecting cable. The glass tube is surrounded by a sheath composed of a conducting plastic. The material proposed for the sheath is a cured vinyl ester or polyethylene saturated with crystalline potassium chloride, polyvinyl chloride or epoxy resin, a conducting additive being added in each case.