Datasheet: Submersion/Insertion pH/ORP Sensors - Models 396P and 396PVP

The reference junction provides an electrical connection between the reference electrode and the sample, and helps maintain a stable reference potential, regardless of the change in sample pH. The TUpH reference electrode junction, (the entire plastic tip surrounding the glass pH electrode), maintains a steady reference signal even in the dirtiest of applications because it resists plugging (a common cause of pH signal drift).