ORP electrodes, unlike pH electrodes, do not need to be calibrated.
While ORP electrodes do not need calibration, they do need to be conditioned prior to use. When the electrode is new, soak the electrode in storage solution. This will enhance the flow of the reference junction.
Checking the Electrode Response
To check the function of the electrode, immerse the tip in the ORP solution HI7021L or HI7022L. The mV reading should be +/- 10 mV from the value indicated on the bottle. If the reading is not within the +/- 10 mV, oxidizing or reduction treatment with the HI7092L or HI7091L is required. It will also prepare the electrode's surface for measurement, and it will speed the initial electrode response time.
Inline Electrode Response
Since inline process electrodes are already in solution, a simple test with either HI7021L or HI7022L will show you the electrode's condition. Should your probe not be accurate enough after conditioning and testing, follow a standard cleaning procedure.