This part of IS0 6293 specifies a method for the determination, by colour-indicator titration, of the amount of constituents in petroleum products that will saponify under the conditions of the test. The method is applicable to materials having saponification numbers in the range 2 mg/g KOH to 200 mg/g KOH. Compounds of sulfur, phosphorus, halogens and some other compounds interfere by reacting with the alkali and acids under the test conditions.