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How to Know When to Replace Hanna Electrodes

Hanna testing meters measure various chemical and physical properties of liquids and are used for scientific research, chemical-related industries and medical laboratories. Hanna meters include pH meters to test acidity and alkalinity as well as ORP meters to test for oxidation potential. The meters rely on precision glass-encased metal electrodes that you connect to the meter and place in the solution you are testing for an accurate reading. After repeated use or mishandling, the electrodes can wear out or break. When test results show possible electrode failure and the electrode appears worn or broken, it is time to replace it.

Instructions

- 1
  Remove the protective cap from your Hanna electrode and set it aside. Rinse the electrode with tap water to remove any salts that may have formed.
- 2
  Lower the protective rubber sleeve or remove the electrode plug on all electrodes except gel or solid-filled models so that air can circulate through the reference chamber of the electrode.
- 3
  Add additional electrolyte through the filling hole as recommended for the type of pH electrode you are using if the electrolyte has dipped below the 1/2-inch line on the side of the electrode.
- 4
  Soak the tip of the electrode in Hanna Electrode Storage Solution (HI 70300) or in pH 4.0 buffer solution or tap water for two hours if the tip is dry.
- 5
  Connect the electrode to the meter and calibrate it as necessary according to the instructions for your model of Hanna meter.
- 6
  Immerse the electrode in the solution that you want to test. Clean it and immerse it in another solution, such as a pH buffer solution for which you know the exact pH.
- 7
  Compare the results. If the results show that the two solutions have the same pH, this is an incorrect response that is known as "no slope" and it indicates a possible defective electrode. Examine the electrode for surface defects including cracks in the glass, bulb or stem of the electrode. Replace the electrode if you see any clear surface damage.
- 8
  Change the batteries in your meter and clear the memory according to the directions for your Hanna meter if you do not see any imperfections and get a "no slope" series of readings. Clean the electrode with deionized or distilled water and repeat Steps 6 and 7. Replace the electrode even if it does not appear damaged in the event you still get "no slope" results.

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