The standard combined electrode for measurement of ORP is filled with KCl gel (0 % silver ions) and contains a salt distillate which guarantees longer stability times. The discharge system is in cartridge form. The combined electrode in the version with PTFE ring diaphragm is especially suited for service under difficult conditions, for example, service in clarification plants or with oily and very soiled media. The electrode is pressure resistant up to 10 bar. Its dimensions are: 120 x 12 mm (DIN 19 263). Selection of ORP electrodes The selection of the ORP electrode depends primarily on the type of measured medium. The following basic rules should be followed: ld-electrode for oxidizing media, for example cyanide oxidation, nitrite oxidation, ozone measurement and hydrogen-peroxide measurement atinum electrode Platinum for reducing media, for example chromate reduction, chlorine dosing in swimming pools.