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HOW TO USE AND MAINTAIN MCMCOPPER 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 recommendedwhen 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.See page two.

1. It is important to inspect Copper Sulphate Reference Electrodes before use. Make sure the copper rodis fully burnished. Remove any and all contaminants by using a new, unused, non-metallic scouring pador sandpaper. Green scouring pads are recommended for the procedure. When green scouring pads areunavailable, 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 beforethe rod assembly is reattached to the tube. The MCM copper rod assemblies are made with the purest copperobtainable. These copper rods can become contaminated by the pH from ungloved fingers, dirt, oil and anyother foreign substance it may come in contact with before being reattached to the tube. Inspect the rubbero-ring and replace the o-ring if it appears to be damaged. Copper Sulphate is a corrosive mineral and shouldbe 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. 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 electrodemay 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 CuSo4and H

2O solution becomes dark blue in color and completely

saturated with the CuSo4. There should always be CuSo

4crystals at the bottom of the electrode to insure

a saturated solution.

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 CuSo4and H2O and allowed to dry. Before using the electrode thisceramic plug assembly must become moistened by the solution contained within the electrode. Failure toallow the ceramic plug assembly to moisten for at least 24 hours will cause the electrode to indicate falsereadings 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, morefrequent rejuvenation may be desirable. For consistent results, we recommend using the highest purity CuSo

4

Crystals possible.

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Bulk Preparation Steps:

NOTE: This procedure can be applied to the previous preparation steps in anticipation of upcoming jobs where a largeamount 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. H2

O).

2. Place ceramic plug assemblies in a clean container and pour the CuSo4

solution over the top until the plug

assemblies are completely submerged. Allow plug assemblies to remain in this solution for 24 hours. Coverthis solution and plug assemblies, so contamination will not occur. Mark this mixture as hazardous, per theMSDS on CuSo

4.

3. Check the rod assembly and make sure the copper rod is completely burnished. Attach the rod assembly tothe tube. Do not over torque o-ring.

4. Fill 1/3 of the tube (approx. 5 grams) with CuSo4crystals. Add CuSo

4solution (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. Do not over torque the o-ring.

6. Put on the plug end cap. NOTE: wait 24 hours for best results.

Precautions:

STORAGE: CuSo4will 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 pittedby deteriorating CuSo

4and the CuSo

4will 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 safemanner and replace with fresh. Do not store the electrodes in a damp atmosphere. Some types of fungusor 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 ofsufficiently high impedance (10 megohms or greater) so that contact resistance, which can occur betweenelectrode and soil, does not affect readings. Selectable impedance, which can be obtained by using the MCMmodel LC-4 meter, is recommended to verify that contact resistance (poor contact to soil, structure or testleads) is minimized or eliminated. The LC-4 voltmeter is specifically designed for this and contains thefunction of selecting proper testing impedance. Also available for this unit is a selectable input impedanceadapter, 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 otheritems will add resistance and result in inaccurate readings. MCM reference electrodes are designed to bedurable, but over time, the ceramic plug assembly will become contaminated by foreign materials and becomeworn or cracked. At this point, the replacement of the ceramic plug assembly is highly recommended.If the CuSo

4mixture within the electrode becomes cloudy white, reverse osmosis has occurred and

rejuvenation is recommended.

Low Temperature Precautions: When the temperature in which the electrodes are used or stored is belowfreezing, the CuSo

4solution within the electrode may freeze. Frozen CuSo

4solution will cause the internal

resistance of the electrode to become very high. As a result, its virtually impossible to obtain a correctreading. Further, as this solution freezes, it is possible that the expansion of the solution may cause theceramic plug assembly to split. MCMs Electrode Anti-Freeze Solution or Anti-freeze Leak Stop Gel should beused at freezing point. While this solution is basically designed for use in low temperature applications, it maybe used throughout the year.

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Testing Electrodes for Accuracy: After prolonged use, the copper sulfate can become contaminated byoutside elements (reverse osmosis). This will cause faulty readings to occur and generate errors. To checkyour electrode for this type of error the following is recommended. A new electrode should be prepared as astandard. This standard electrode should be a new reference electrode. One electrode should always bemaintained as a standard and not used in the field. Using an LC-4 voltmeter set the DC voltage scale to200mv and the input impedance to 200 as well. Attach the standard reference electrode to the negative (orcommon) side of the meter and the electrode to be tested to the positive DC side. Place the two electrodes

end to end, making contact with each plug assembly. If you are unable to get a reading, apply a couple ofdrops of CuSo

4and H

2O solution to the plug assemblies to increase the conductivity. Once contact is made,

you will be checking the potential of the two electrodes. The difference between the standard and theelectrode being tested should have a reading of no more than 5mv positive or 5mv negative. Since CuSo

4

Electrodes are affected by temperature, it is necessary to allow the electrodes needing testing, as well as thestandard electrode, to settle to the same room temperature. 72 degrees F is ideal. When it is found that anelectrode has more than a +or 5mv reading, the electrode should be rejuvenated following the stepsmentioned in the beginning of this informational sheet. The end-to-end method of testing on the RE-5C plugassemblies can sometimes be inaccurate. To test an electrode where the RE-5C type plug assemblies areused, you will need to use a CuSo

4solution in a cup or beaker. Instead of placing the electrodes end to end,

dip both into the CuSo4solution. The solution will act as a bridge and relatively produce the same result.

Submerging Electrodes: When using a reference electrode completely submerged in water, the electrodetube should be kept completely filled with CuSo

4solution or gel. This will limit the possibility of outside water

being forced into the electrode through the ceramic plug assembly. Even when the tube is completely filled,some reverse osmosis will occur. Submerging the electrode in areas where the water is highly contaminated,such as that found in manholes, lift stations or in seawater, the CuSo

4solution should be changed more

frequently. The solution should be changed every other day depending on the amount of contaminants youare working in. You will be able to tell how contaminated your electrode has become by testing its potentialagainst an unused standard electrode.

ELECTRODE MIXTURES (CuSo4 to H2O)

RE-5 and 5Cs .042 lbs. / 20 grams CuSo4to H

2O

Re-7 .024 lbs. / 11 grams CuSo4to H

2O

Re-375 .004 lbs. / 1.5 grams CuSo4to H

2O

RE-3A .413 lbs. / 187.5 grams CuSo4to H

2O

Instruments and Equipment for the Corrosion Engineer

3020 Aviation Blvd. ~Vero Beach, FL 32960

Tel: 772-794-9448 ~Fax: 772-794-9908sales@mcmiller.com~www.mcmiller.com

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