General Purpose Inline Process pH Sensor with Integrated Digital Electronics for "Plug and Play" with Hach sc Digital Controllers - Glass pH Electrode, Stainless Housing, Immersion Mount, 10m Cable. This field-proven technique uses three electrodes instead of the two normally used in conventional pH sensors. Process and reference electrodes measure the pH differentially with respect to a third ground electrode. The end result is unsurpassed measurement accuracy, reduced reference junction potential, and elimination of sensor ground loops. These process pH sensors provide greater reliability, resulting in less downtime and maintenance.