Electro-Chemical Devices (ECD) DCA-23 - Manual (Page 13)

DCA-23 Page 7
3.0 OPERATION
This section will provide a basic overview of the DCA-23 Analyzer. It covers the basic Menu structure and
the functions of the MENU SELECT keys and the CALIBRATE keys.
3.01 Measurement Overview
Sea water contains approximately 68 mg/L of bromide. When chlorine is added to sea water, the
bromide ion is oxidized to hypobromous acid (HOBr) and hypobromite (OBr-) by the Free Chlorine (HOCl
and OCl-). This is a very rapid reaction and essentially all of the chlorine is instantaneously converted
into bromine and bromamines. The DCA-23 measures the temperature, pH and Total Residual Oxidant
(TRO) potential of the seawater and converts them into an equivalent “ppm chlorine” value, using the
stored TRO/pH/Cl ppm table, see below. Even though there is no chlorine present, the DCA-23 displays
Chlorine ppm in order to conform to existing conventions. TRO is defined as the total oxidizing capacity
(free and combined) of the sea water that is available after chlorination.
Table #1 TRO/pH/Equivalent Chlorine ppm