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5.6.2 pH isothermal measurement principle
The closer the temperature of the sample solution to the calibration solution, the more accurate the
measurements will be. Please be aware of this principle.
5.6.3 Restore to factory default setting
Instrument has a factory default setting function,
please refer to parameter setting clause 1.4
(see Diagram-8). With this function, all calibration data
is deleted and the meter will be calibrated to the theory
value (pH value of zero electric potential is 7.00, the
slope is 100%). Some function settings restore to the
original value (refer to clause 8.3). When calibration or
measurement fails, please restore the meter to factory
default setting and then perform re-calibration or measurement. Please note that all the data deleted will
not be retrievable if the meter is restored to factory default setting.
6
mV Measurement
6.1
ORP measurement
Press
key, and switch the meter to mV measurement mode. Connect ORP probe (need to
purchase it separately) and dip it in sample solution, stir the solution briefly and allow it to stay in the
solution until
icon appears. The reading obtained is ORP value.ORP stands for Oxidation
Reduction Potential. It means oxidation-reduction potential of solution.
ORP is the measurement index for the oxidation-reduction ability of water solution. Its unit is mV.
6.2
Notes for ORP measurement
6.2.1 ORP measurement does not require calibration. When the user is not sure about ORP
probe quality or measuring value, use ORP standard solution to test mV value and see whether
ORP probe or meter works properly.
6.2.2
Clean and activate ORP probe: After the probe has been used over long period of time, the
platinum surface of the ORP probe will get polluted which causes inaccurate measurement and
slow response. Please refer to the following methods to clean and activate ORP probe:
(a)
For inorganic pollutant, submerge the probe in 0.1mol/L dilute hydrochloric acid for 30 minutes, wash
it in purified water, and then submerge it in electrode soaking solution for 6 hours.
(b)
For organic or lipid pollutant, clean the platinum surface with detergent, then wash it in purified water,
then submerge it in electrode soaking solution for 6 hours.
(c) For heavily polluted platinum surface on which oxidation film is formed, polish the platinum surface
with toothpaste, then wash it in purified water, then submerge it in electrode soaking solution for 6
hours.
Diagram-8
