May be used as a quality-control test during manufacture and conversion of PVC compounds and for coloured compounds. Is not recommended for compounds in the form of dry blends. Defines the stability time. The principle consists in exposing a sample of the material at an agreed temperature in a gas stream, followed by absorption of the hydrogen chloride evolved in a 0.1 mol/ l solution of sodium chloride. The amount of hydrogen chloride evolved is measured by recording the change in pH of the sodium chloride solution. Figures show the general arrangement of apparatus and details of the dehydrochlorination cell. Together with three other parts of ISO 182, cancels and replaces ISO Recommendation R 182:1970.