Measuring the Liquid Content of Foam

For metastable foams, indirect examination of foam stability using the conductivity module PA4550 to measure the alteration in the liquid content is particularly time-efficient, and allows a correlation with other foam properties.

The decay of foam is preceded by liquid drainage from the foam lamellas. The speed and extent of the drainage normally allows conclusions to be drawn about the stability of the foam in relation to other samples. This spares the waiting time for the actual and frequently very slow decay.

The Module PA4550 for the Dynamic Foam Analyzer DFA100 from Krüss measures the liquid content of the foam via its conductivity in parallel at seven different heights of the foam column, so that drainage is followed as a function of time and height. Foam generation is reproducible by means of a controlled flow of gas through a frit. The software records independent measurement curves for all electrodes and gives the maximum moisture content as a percentage together with the half-value time for each measuring height.

The very comfortable handling of the electrodes is also new. They are arranged on two strips that are inserted in the standard measuring column of the DFA100 and connected up in only a few seconds. In the moisture determination measuring mode the standard optical foam height measurement is also carried out simultaneously.