Dissolved oxygen probe

Claim 1

An immersible probe for continuously measuring the concentration of oxygen dissolved in a liquid, said probe comprising: A. a tubular insulating casing having an electrolyte chamber whose open mouth is at the lower end of the casing, said chamber having an insulating stem coaxially disposed therein, B. a noble metal measuring electrode mounted at the tip of said stem adjacent the mouth of said electrolyte chamber, C. a diffusing membrane permeable to oxygen, said membrane closing the mouth of said electrolyte chamber and covering said measuring electrode, and D. a tubular copper counter-electrode whose lower end encircles the other end of said stem and lies within said chamber, the upper end of said counter-electrode projecting outside said chamber and being connected to a first terminal, a connection between said measuring electrode and a second terminal external to said chamber being effected by a lead passing through said stem and said tubular counter-electrode, said chamber being filled with an aqueous solution of potassium hydroxide to bridge said electrodes to form an oxygen-sensitive galvanic cell generating a current proportional to the concentration of oxygen diffusing through said membrane, the copper counter-electrode reacting with hydroxide ions to produce copper oxide which adheres to the copper without forming a precipitate that would otherwise clog said cell.