CONSTRUCTION AND THERMODYNAMIC PERFORMANCE OF AN AG-AGCL REFERENCE ELECTRODE FOR USE IN HIGH-TEMPERATURE AQUEOUS ENVIRONMENTS CONTAINING H-2 AND H-2S

The impetus for this work comes from the geothermal industry and is part of an ongoing research program to develop in-line and down hole instrumentation to measure water chemistry in geothermal fluids. An Ag-AgCl reference electrode for temperatures to 250 C was demonstrated to have a Nernstian response by use of concentration cells with transference. A ZrO//2 electrode body acting as a diffusion barrier was incorporated which permits thermodynamic operation at high temperatures in environments containing significant quantities of H//2 and H//2S.