(a) These methods cover procedures for the determination of residual chlorine in industrial water. Provision is made for the determination of total chlorine, free available chlorine, and combined available chlorine in the presence of the amount of color, turbidity, iron, manganese, chromium, nitrites, and organic matter normally present. Three methods are given, as follows: Sections Referee Method (Amperometric Titration Method) 5 to 15, Non-Referee Method A (Colorimetric Method) 16 to 24, Non-Referee Method B (Dilution — Colorimetric Method) 25 to 31. (b) The referee method is amperometric, and is not subject to commonly encountered interferences. This method is applicable to all types of industrial water having a residual chlorine content of not more than 5 ppm. Non-referee method A is colorimetric, and is subject to interferences by certain ions and by elevated temperatures. This method is not applicable to highly colored or turbid water. Non-referee method B is a dilution-colorimetric method subject to interferences similar to non-referee method A, but is applicable to water containing high amounts of residual chlorine. (c) Methods for the determination of residual chlorine in water containing appreciable amounts of industrial waste are given in the Methods of Test for Residual Chlorine in Industrial Waste Water (ASTM Designation: D 1427).