Method for the Determination of Available Chlorine in Liquid Chlorine for Drinking Water Treatment Chemicals (NIEA D435.22C)

This method applies to on-site determination of available chlorine (Cl₂) in liquid chlorine used as a drinking water treatment chemical. Personnel shall vaporize liquid chlorine and introduce it into a fixed-volume measuring tube, absorb chlorine gas with potassium iodide solution, measure the residual gas volume, and calculate the volume fraction of available chlorine from the difference between introduced and residual gas volumes. Samples shall be taken according to the prescribed number of containers. Cylinders with leakage, damage, corrosion, or abnormal pressure shall not be sampled. Samples shall be tested directly on site and need not be preserved or transported. Each sample shall undergo duplicate analysis, with relative percent difference within 0.2%; appropriate protective measures, leak testing, and control of fugitive chlorine emissions are required.