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Instruction Sheet TUpH 396P and 396PVP Sensors
LIQ_MAN_ABR_396P_396PVP July 2013
ORP Calibration
1. After making an electrical connection between the sensor and the instrument, obtain a standard solution of
saturated quinhydrone. This can also be made quite simply by adding a few crystals of quinhydrone to either pH 4 or
pH 7 buffer. Quinhydrone is only slightly soluble, therefore only a few crystals will be required.
2. Immerse the sensor in the standard solution. Allow 1–2 minutes for the ORP sensor to stabilize.
3. Adjust the standardize control of the instrument to the solution value shown in the table below. The resulting
potentials, measured with a clean platinum electrode and saturated KCl/AgCl reference electrode, should be within
±20 millivolts of the value shown in the table below. Solution temperature must be noted to ensure accurate
interpretation of results. The ORP value of saturated quinhydrone solution is not stable over long periods of time.
Therefore, these standards should be made up fresh each time they are used.
4. Remove the sensor from the buffer, rinse, and install in the process.
Maintenance for ORP Electrode
Electrodes should respond rapidly. Sluggishness, offsets, and erratic readings are indicators that the electrodes may need
cleaning or replacement.
1. To remove oil deposit, clean the electrode with a mild non-abrasive detergent.
2. To remove scale deposits, soak electrodes for 30 to 60 minutes in a 5% hydrochloric acid solution.
3. ORP (metallic) electrodes should be polished with moistened baking soda.
pH 4 Solution pH 7 Solution
Temp °C
20 25 30 20 25 30
mV Potential
268 264 260 94 87 80
Installation
Figure 1. Dimensional Drawing