There is a diverse set of chemical formulations that ca […]
There is a diverse set of chemical formulations that can be effective either to prevent Foam Pump(KEXON) forming or to destroy it once it has formed. In practice, most foam-dispersing chemicals can serve either role. Each anti-foam or de-foamer agent is specifically developed for individual applications and the world-wide market for these essential evils is worth billions of pounds per annum. Commonly used agents are insoluble oils, polydimethylsiloxanes and other silicones, certain alcohols, stearates and glycols.
The most universal characteristic of any de-foamer is the fact that it is surface active. Most are insoluble. However, some are water-soluble which only adds to the complexity. The latter type has a property known as inverse solubility. An increase in the temperature of an aqueous system in which the de-foamer is present causes a decrease in its solubility. At or above the cloud point (the initial effective temperature), the de-foamer separates from solution and acts as an effective de-foamer. Reduction of the system temperature below the cloud point enables the de-foamer to become solubilised again.
Insoluble de-foamers have to be formulated so that they will be dispersed as an emulsion. The surface-active nature of the material causes it to spread rapidly onto any air-liquid interface that it encounters.