KROHNE OPTISENS ORP 8590 EN - Manual (Page 26)

6
TECHNICAL DATA
26
OPTISENS ORP 8590
www.krohne.com 01/2014 - 4001933801 MA OPTISENS ORP 8590 R01 en
Technical data
6.1 Measuring principle
6.1.1 ORP measurement
The oxidation reduction potential, ORP in short, is the measurement for the concentration of
oxidising and reducing agents in water. Its value is influenced both by pH and temperature. ORP
is a sum parameter that gives no information on the concentration of a single substance in a
mixture.
ORP measurements are used to monitor chemical reactions involving electron transfer. In
drinking water treatment it can be found in ozone treatment and the removal of iron, manganese
and nitrate as well as in disinfection steps. In swimming pools the German DIN 19643 requires
ORP measurements as a hygiene parameter and decrees maximum and minimum values for
fresh water, pool water, and salt water. In wastewater treatment ORP is measured in the
denitrification process and in detoxication of industrial wastewater.
The ORP sensor consists of a measuring electrode of platinum or gold and a reference of e.g.
Ag/AgCl. The potential of the measuring electrode changes with the concentration of reducing
and oxidising agents and is measured against the reference. The measured values can be
recalculated to fit literature values based on NHE (normal hydrogen electrode) as reference.
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