Working principle
Electrolyte and osmotic membrane separates the electrolytic cell and water samples, permeable membranes can selectively to ClO- penetration; between the two electrode has a fixed potential difference, current intensity generated can be converted into residual chlorine concentration.
At the cathode: ClO- + 2H+ + 2e- → Cl-+ H2O
At the anode: Cl- + Ag → AgCl + e-
Because in a certain temperature and pH conditions, HOCl, ClO- and residual chlorine between fixed conversion relationship, in this way can measure the residual chlorine.