Copper-Sulfate Reference Electrodes

(often referred to as “Half Cells”)

The M.C. Miller Co., Inc. “RE-” series of electrodes provides three areas of improvement over other electrodes formerly available. These are: a Lexan Tube, a CPT ceramic plug, and a strong top cap with a 1/4″ high-purity copper rod with 1/4 x 20 external thread and brass knurled nut. The CPT ceramic plugs offer numerous advantages, including:

• The porosity of the CPT ceramic plug is uniform and controlled.
• All ceramic plugs are alike.
• The CPT ceramic plug is fast wetting, and the electrode can be used within minutes after filling. (It often takes many hours to wet up a wood plug).
• The CPT ceramic plug is pre-treated to provide lower electrical resistance which remains low as long as the plug is moist with saturated copper-sulfate solution.
• A CPT ceramic plug can become thoroughly dried out, and it will re-wet in a few minutes with the same low resistance. It is not necessary to keep the electrode in a position where the solution will be in contact with the plug.
• Tests indicate that it is not necessary to keep the CPT plug covered to prevent drying when not in use. However, it is desirable to do so, a protective cap is provided for this purpose.
• The CPT ceramic plug is housed in a high-density polyethylene fitting, which helps protect it against chipping or breaking in the event it is accidentally dropped.

The brilliant orange color of the Lexan tube was selected to provide an electrode which can be readily seen in grass, and to help locate it when it is placed remotely or when it breaks loose from the “pull-in” lead. Some of its other advantages include:

• The Lexan tube used in the Model RE-5, RE-5C and RE-7 electrodes is extruded in two colors, orange and clear. The orange is opaque and provides a sun shield to eliminate the small potentials which sometimes occur with full transparent tubes. A clear transparent section extending the length of the electrode provides a window for visual inspection to observe the condition and level of the copper-sulfate solution. This window is essential to maintain the electrode in good condition. Lexan is also used in the body of the Model RE-3A Electrode, but the color is painted on the inside rather than extruded. An inspection window is provided.
• The Lexan tube is highly resistant to damage. It can be misused, pushed into soft ground, dropped, and carried in a tool kit without breaking.

The top caps of the Model RE-5, RE-5C and RE-7 are heavy and strong. They are machined out of high-density polyethylene rod, and are extra thick where the copper rod is threaded through. A neoprene gasket provides a liquid and air tight seal. The top cap of the Model RE-3A is molded Cycolac, as is the plug receptacle.