Chapter 7 Appendix; Automatic Ph Buffer Recognition Feature; Electrode Condition Icon - Thermo Scientific Orion Star A111 Reference Manual

Chapter 7 Appendix

Automatic pH Buffer Recognition Feature

The Orion Star A111 benchtop pH and Star A121 portable pH meters are capable of automatically recognizing 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 ± 60 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

Electrode Condition Icon

The electrode condition icon indicates the performance of the pH electrode, based on the last saved calibration and
electrode measurement stability.
Icon
Blinking
Thermo Scientific Orion Star A111 Benchtop and Star A121 Portable pH Meters
mV Range
+255 to +375
+117 to +237
-60 to +60
-237 to -117
-383 to -263
Definition of Icon
Electrode condition is good and the electrode slope is 95 to 105 %.
Electrode condition is fair and the electrode slope is 85 to 115 %.
Electrode condition is bad and the electrode slope is less than 85 % or greater than 115 %.
Consult the electrode user guide for instructions on how to clean, condition and
troubleshoot the electrode.
DIN pH Buffer Set
Buffer mV Range
1.68 +255 to +375
4.01 +117 to +237
6.86 -52 to +68
9.18 -189 to -69
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