Electrode Calibration
ORP readings can be reported using the absolute mV values or the EH mV values. EH mV values give the corresponding mV values that would be obtained using a Standard Hydrogen Electrode (SHE), also known as the Normal Hydrogen Electrode (NHE). Orion ORP standard, Cat. No. 967901 or 967961, allows operators to correlate measurements to the EH mV value with an Orion ORP electrode.
The relative mV mode can be used to calibrate the ORP electrode so the electrode reads the EH mV values in samples. When an ORP electrode is calibrated to read EH mV values, the resulting sample readings can be compared among multiple meter and electrode systems.
Note: If the meter can perform an automatic ORP calibration using an EH mode, refer to the meter user guide for detailed instructions on the meter calibration procedure.
1.Set the meter to the relative millivolt mode. Refer to the meter user guide for detailed instructions.
2.Place the ORP electrode in ORP standard, Cat. No. 967901 or 967961.
3.Set the meter to the EH mV value of the ORP standard at the measured temperature using the information in Table 1.
Table 1– ORP Standard Values
Absolute mV values may vary by ± 60 mV
Temperature | EH Value | Absolute Value | Absolute Value |
(°C) | (mV) | with Cat. No. | with Cat. No. |
|
| 900011 Filling | 900001 Filling |
|
| Solution (mV) | Solution (mV) |
0 | 438 | 218 | 176 |
1 | 437 | 218 | 176 |
2 | 437 | 218 | 176 |
3 | 436 | 218 | 176 |
4 | 435 | 218 | 176 |
5 | 435 | 218 | 176 |
6 | 434 | 218 | 176 |
7 | 433 | 218 | 176 |
8 | 433 | 218 | 175 |
9 | 432 | 219 | 175 |
Redox/ORP Electrode User Guide |