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Appendix A Advanced Features
Automatic pH Buffer Recognition Feature
The Orion V
pH 1.68, 4.01, 7.00, 10.01 and 12.46 buffers or pH 1.68, 4.01, 6.86, and 9.18 buffers during a pH calibration, depending
on the pH buffer set that is selected in the setup menu. During a calibration, the meter uses the selected buffer set
and the raw mV reading of the pH electrode in the buffer to recognize and display the buffer value at the measured
temperature. The raw mV reading of the pH electrode in the buffer must be about ±30 mV from the theoretical mV
reading of the buffer in order for the meter to automatically recognize the buffer.
USA pH Buffer Set
Buffer
1.68
4.01
7.00
10.01
12.46
Testing a pH Electrode for Automatic Buffer Recognition
To verify that the raw mV reading of the pH electrode in use is ± 30 mV from the theoretical mV reading of the buffer,
and therefore verify that the pH electrode in use is capable of performing automatic buffer recognition, perform the
following procedure.
1. Set the measurement mode to mV. Prepare the pH electrode according to the instructions in the pH electrode
user guide.
2. Rinse the pH electrode with distilled water, blot it dry with a lint-free tissue and place the pH electrode into a pH
4.01 buffer at approximately 25 °C.
3. Wait for the measurement to stabilize and record the mV value of the pH 4.01 buffer when the meter indicates that
the measurement is stable. The read type selected in the setup menu will determine how the mV measurements are
displayed by the meter.
4. Remove the pH electrode from the pH 4.01 buffer.
5. Rinse the pH electrode with distilled water, blot it dry with a lint-free tissue and place the pH electrode into a pH
7.00 buffer at approximately 25 °C.
6. Wait for the measurement to stabilize and record the mV value of the pH 7.00 buffer when the meter indicates that
the measurement is stable.
7. The mV reading of the pH electrode in pH 4.01 buffer should be in the range of +207 to +147 mV and the mV reading
of the pH electrode in pH 7.00 buffer should be in the range of -30 to +30 mV. If the mV readings of the pH electrode
are in the correct ranges, the pH electrode is capable of performing automatic buffer recognition. If the mV readings
of the pH electrode are not in the correct ranges, the values of the pH buffers will need to be manually entered
during a pH calibration.
Thermo Scientific Orion V
s
Meter and pH with LogR Temperature module systems are capable of automatically recognizing
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mV Range
+285 to +345 mV
+207 to +147 mV
- 30 to + 30 mV
-207 to -147 mV
-293 to -353 mV
s
pH with LogR Temperature Module
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DIN pH Buffer Set
Buffer
mV Range
1.68
+285 to +345 mV
4.01
+207 to +147 mV
6.86
+38 to -22 mV
9.18
-99 to -159 mV
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