DIN 53902:2016-07

This standard has been prepared by Working Committee NA 062-05-63 AA "Anwendungstechnische Prüfverfahren für Tenside" ("Application technology test methods for surfactants") at DIN Standards Committee for Materials Testing (NMP). This standard specifies a method for determining the foaming power of surfactants and products made from them; in particular bath additives, regardless of their ionic character. The determination is carried out according to this standard at (50 ± 2) °C. Determinations at temperatures above 50 °C are also possible with the test equipment used. However, temperatures deviating from (50 ± 2) °C shall be agreed. The method is not applicable to easily hydrolysing or not completely soluble surfactants as the sample solutions may not be turbid or contain sediment. Surfactants sensitive to water hardness can only be measured in soft water. In general, with any foam measurement method the mechanical energy with which the air is incorporated has to be adapted to the process of foam formation to be investigated in practice. The method is therefore not suitable for measuring foaming in washing machines and dishwashers and the foaming of wastewater or of highly diluted solutions, such as river water containing surfactants. Foaming power and foam persistence can also be altered by even slight variations in the composition of the products.