How to electrode - M.C. Miller Downloadable …

1 REF. 11/30/10 - 1 - HOW TO USE AND MAINTAIN MCM COPPER SULPHATE REFERENCE ELECTRODES WARNING! MCM reference electrodes use Copper Sulphate. Copper Sulphate should be handled with care. Rubber gloves, safety glasses or face shields, waterproof apron and inhalant protection are highly recommended when working with copper sulphate (CuSo4). Single Preparation Steps: When rejuvenating or setting up a new electrode , follow these steps. NOTE: When rejuvenating or setting up more than one electrode , the bulk procedure is recommended.

2 See page two. 1. It is important to inspect Copper Sulphate Reference Electrodes before use. Make sure the copper rod is fully burnished. Remove any and all contaminants by using a new, unused, non-metallic scouring pad or sandpaper. Green scouring pads are recommended for the procedure. When green scouring pads are unavailable, sandpaper can be used. Oxide type sandpaper must be avoided! Oxide sandpaper will introduce unwanted metals into the surface of the copper rod assembly. 2. Once the copper rod assembly has been fully burnished, avoid any contamination, which may occur before the rod assembly is reattached to the tube. The MCM copper rod assemblies are made with the purest copper obtainable.

3 These copper rods can become contaminated by the pH from ungloved fingers, dirt, oil and any other foreign substance it may come in contact with before being reattached to the tube. Inspect the rubber o-ring and replace the o-ring if it appears to be damaged. Copper Sulphate is a corrosive mineral and should be handled with care. Leaking reference electrodes may cause damage to expensive test equipment. 3. Reattach the rod assembly to the tube. Hand tighten only as not to damage the rubber o-ring by over torquing. But, be sure to tighten well enough that the electrode does not leak. 4. Add Copper Sulphate to the tube (see cross-reference chart for amount) and then add water up to the bottom of the plug assembly threads.

4 Use only High Purity Copper Sulphate (CuSo4 (available from MCM)) and Deionized or Distilled Water. Be sure to remove any crystals that may have stuck to the threads of the tube. If copper sulphate crystals are present on the threads when the plug assembly is reattached, the electrode may leak at this thread junction. 5. Screw the presaturated plug assembly onto the tube end, making sure again not to over torque the o-ring. 6. Shake the electrode until the CuSo4 and H2O solution becomes dark blue in color and completely saturated with the CuSo4. There should always be CuSo4 crystals at the bottom of the electrode to insure a saturated solution.

5 7. Allow the electrode to set for a 24-hour period before use. The electrode ceramic plug assemblies are presoaked at the factory with a solution of CuSo4 and H2O and allowed to dry. Before using the electrode this ceramic plug assembly must become moistened by the solution contained within the electrode . Failure to allow the ceramic plug assembly to moisten for at least 24 hours will cause the electrode to indicate false readings when used. Note: Under average conditions, the electrode should be emptied and cleaned out every two or three months. However, if the electrode is allowed to remain in prolonged contact with low resistivity soil or water, more frequent rejuvenation may be desirable.

6 For consistent results, we recommend using the highest purity CuSo4 Crystal s possible. REF. 11/30/10 - 2 - Bulk Preparation Steps: NOTE: This procedure can be applied to the previous preparation steps in anticipation of upcoming jobs where a large amount of reference electrodes will be needed (apply above warning). 1. In a clean container completely mix CuSo4 and Deionized or Distilled Water. (2 lbs. CuSo4 to 3000 ml. H2O). 2. Place ceramic plug assemblies in a clean container and pour the CuSo4 solution over the top until the plug assemblies are completely submerged.

7 Allow plug assemblies to remain in this solution for 24 hours. Cover this solution and plug assemblies, so contamination will not occur. Mark this mixture as hazardous, per the MSDS on CuSo4. 3. Check the rod assembly and make sure the copper rod is completely burnished. Attach the rod assembly to the tube. Do not over torque o-ring. 4. Fill 1/3 of the tube (approx. 5 grams) with CuSo4 crystals. Add CuSo4 solution (made in step 1) to the tube up to the bottom of the plug assembly threads. Adding extra CuSo4 crystals to the tube will insure the mixture within the tube will stay completely saturated. 5. Attach the presoaked ceramic plug assembly to the tube.

8 Do not over torque the o-ring. 6. Put on the plug end cap. NOTE: wait 24 hours for best results. Precautions: STORAGE: CuSo4 will deteriorate over time. Electrodes, which are purchased in bulk and stored for later use, should always be checked before placing into service. Copper rods can become tarnished or pitted by deteriorating CuSo4 and the CuSo4 will become unusable. The copper in this condition will become contaminated, which will cause inaccurate readings. CuSo4 should have a rich, deep blue color. If the crystals appear to have become whitened or have the appearance of being dehydrated, discard in a safe manner and replace with fresh.

9 Do not store the electrodes in a damp atmosphere. Some types of fungus or mold can contaminate the ceramic plug assemblies. Always rotate your stock using the FIFO (First In, First Out) method. Common Source of Error: The voltmeter used in conjunction with reference electrodes should be of sufficiently high impedance (10 megohms or greater) so that contact resistance, which can occur between electrode and soil, does not affect readings. Selectable impedance, which can be obtained by using the MCM model LC-4 meter, is recommended to verify that contact resistance (poor contact to soil, structure or test leads) is minimized or eliminated. The LC-4 voltmeter is specifically designed for this and contains the function of selecting proper testing impedance.

10 Also available for this unit is a selectable input impedance adapter, which can be used with data loggers (also available from MCM). When taking readings, the ceramic plug must come in contact with soil. Vegetation such as grass should be moved out of the way. Grass or other items will add resistance and result in inaccurate readings. MCM reference electrodes are designed to be durable, but over time, the ceramic plug assembly will become contaminated by foreign materials and become worn or cracked. At this point, the replacement of the ceramic plug assembly is highly recommended. If the CuSo4 mixture within the electrode becomes cloudy white, reverse osmosis has occurred and rejuvenation is recommended.