Surface Tension - Measuring Methods

Bubble Pressure Method Through the attraction between the molecules of a liquid, air bubbles within a liquid are also subject to these forces i.e. a bubble formed within a liquid is being compressed by the surface tension. The resulting pressure rises with the decreasing bubble radius. This increased pressure, in comparison to the outside of the bubble, is used to measure surface tension. Air is pumped through a capillary into a liquid. The so created bubble surface bulges hence continuously decreasing the bubble radius.
During this process the pressure rises to a maximum pressure. Here the bubble has its smallest radius. This radius equals the radius of the capillary and forms a half sphere. After passing this point the bubble bursts and breaks away from the capillary. Now a new bubble can form at the capillary. During this process the characteristic course of pressure can be measured in the bubble. From this characteristic course of pressure the surface tension can be calculated.
The Bubble Pressure Method to measure the surface tension is used in our Bubble Pressure - Tensiometers SITA DynoTester, SITA pro line f10, SITA science line t60.