Salt bridge reference electrode

Claim 1

A position-insensitive long-term fixed potential internally wet salt bridge reference electrode assembly immersible in wet and dry corroding electrolytes, comprising: (a) an electrolytically non-conductive generally axially elongated vessel impervious to water, having an open end; (b) a metallic electrode contained within said vessel, remote from said vessel open end; (c) insulated wire means, physically connected to said metallic electrode and extending from the exterior of said vessel, for electrically connecting said metallic electrode to a voltage potential measuring device; (d) a hydrophylic porous electrolytically conductive plug circumscribed by an inner surface of a generally cylindrical wall of said vessel, including electrolytically active metallic salt crystals suspended therein with the salt crystals dispersed throughout the plug, said plug separating said metallic electrode from said vessel open end, an extremity of said plug most proximate said metallic electrode being spaced from said metallic electrode to form a closed compartment bounded by said plug, said metallic electrode and the wall of said vessel, said plug including: (i) a rod-like portion extending into said compartment towards said metallic electrode, for contacting salt crystal-saturated water in said compartment and maintaining simultaneous water-plug and water-electrode contact even when water volume is substantially less than compartment volume and said electrode is oriented with said axially elongated tube substantially skew to vertical; (e) said water, being saturated with crystals of said metallic salt, and being within said compartment for unrestricted flow therethroughout; (f) hydrophylic electrolytically semipermeable barrier means, disposed across said vessel open end, one surface thereof contacting said plug and a second surface thereof forming an external surface of said assembly to contact said electrolyte when said assembly is immersed therein, for resisting escape of ions of said salt for said vessel; wherein said water contacts both said electrode and said plug.