Reference Electrodes (Ag/AgCl, Pd/H2)
The Ag/AgCl reference electrode with external pressure balancing is suitable for most aqueous applications at temperatures up to 300°C. The internal Ag/AgCl electrode rod is immersed in a KCl solution, which is separated from the environment using a porous ceramic frit. The concentration of KCl used depends on the operational environment. For clean-water applications, 0.01 M KCl is used, whereas saturated KCl is used in concentrated solutions, mostly in an H2S salt-water environment.
The lifetime of the Ag/AgCl reference electrode depends on various operating environment parameters. A high operating temperature and pressure, as well as frequent temperature and pressure transients, can shorten the electrode's lifetime. Dilution of the internal KCl solution and contamination of the Ag/AgCl rod are typical damaging mechanisms. However, the electrode is easy to open and service.
Ag/AgCl reference electrodes are manufactured with various dimensions and fittings. Existing ports in your autoclave can be used to add a Cormet electrode. They can be connected to high-input impedance amplifiers or potentiostats.
A Pd/H2 reference electrode acts as a reversible hydrogen electrode (RHE) and follows the H2/H+ equilibrium line as long as the environment is non-oxidising and the pH is known. The palladium electrode is a solid-state electrode with a very easy maintenance procedure. The electrode is manufactured in two versions: 300°C and 360°C.