Thermo Fisher Scientific Eutech PC 700 - Manual (Page 10)

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4.2 Millivolt (mV) Offset Adjustment
Oxidization Reduction Potential (ORP or Redox) is not a precise
measurement, but is useful as a relative indicator. As such, mV offset
adjustment is not meant to enhance accuracy, but rather to make
readings comparable to a reference. Commercial ORP solutions are
often used as a check standard in which a meter/electrode system are
verified to be close to a given value, instead of being used as a
calibration standard in which adjustments are made in an attempt to
match the ORP value.
1) Connect an ORP electrode and press as needed to select mV
(or R.mV).
2) Dip the ORP electrode into a solution with a known mV value
(i.e. Zobel, Light’s, quinhydrone, or iodidetriiodide) and stir.
3) Press when the reading is stable. The primary display shows
the relative millivolt value (R.mV) while the secondary display shows
the factory default mV value.
4) Adjust the R.mV value using or . Press to accept or
to cancel. The meter allows an adjustable maximum value of ±
150 mV from the factory default mV value.
Note: When an offset has been stored successfully, R.mV replaces
mV.
5. CONDUCTIVITY AND TDS CALIBRATION
5.1 Automatic or Manual Calibration
The PC 700 is capable of automatic or manual calibration for
conductivity, and manual calibration for TDS.
In the automatic calibration mode, the meter will automatically select
one of (4) conductivity calibration standard values depending on the
range and normalization temperature being used ( TABLE 1).