Thermo Scientific Orion Versa Star Pro User Manual page 137

Thermo Scientific
Out-Of-The-Box Electrode Check
Follow this procedure to perform a quick evaluation of a new pH electrode and help diagnose a
defective pH electrode.
1. Remove the pH electrode from the box.
2. Connect the pH electrode to the BNC input on the pH/LogR module connected with the
Versa Star Pro meter.
3. If needed, select LogR as the temperature source:
a. In the measurement mode, press the setup key
b. Press the ◄ or ► key to highlight Channel # (the channel number the LogR module is
connected with) and press the f3 (Select) key.
c. Press the ◄ or ►key to highlight Temperature and press the f3 (Select) key.
d. Press the ▲ or ▼ key to highlight Temperature Input and press the ◄ or ► key to
highlight the channel number the LogR module is connected with (i.e. Ch2-LogR).
e. Press the measure (esc) key to return to the measurement mode.
4. Read the resistance value shown on the measurement display.
a. A resistance value of 0 indicates that the pH electrode may be defective.
b. A resistance value other than 0 indicates the pH electrode is responsive. Prepare the
pH electrode according to the instructions in the electrode user manual. Perform the
initial electrode check when the electrode is ready.
Initial Electrode Check
For the most pH electrode diagnostics benefits from the Versa Star Pro meter with pH/LogR
measurement module, establish a regular schedule of resistance testing with the pH electrode.
Perform an initial check of the pH electrode resistance and record the temperature and
resistance value in the provided table, or perform a LogR temperature calibration and export the
calibration information to a computer or printer.
1. Rinse the pH electrode with deionized water and blot dry with a lint-free tissue.
2. Insert the pH electrode into the solution and gently stir the solution.
3. Record the temperature and resistance value for reference.
The pH-sensing bulb thickness and diameter vary among pH electrodes, resulting in normal
variations in resistance values. In most cases, the initial value is not a definitive test of electrode
condition except in extreme cases such as the initial low readings information described below.
When changing pH electrodes, do not be alarmed if the resistance varies dramatically from your
previous electrode.
Initial Low Readings – If the resistance is below 1 MΩ in a solution at room temperature (22 to
27 °C), it indicates a damaged pH electrode. In this case, the electrode will most likely need to
be replaced.
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Appendix A Channel Specific Settings and Features
Orion Versa Star Pro Meter User Manual
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