Definition - What does Anti-Foam Additive mean?
An anti-foam additive is a fuel additive that hinders the formation of foam in industrial process liquids. Anti-foam additives are polysiloxane-based compounds used in multifunctional additive packages. They are used in detergents, food, pharmaceuticals and process industries.
Commonly used additives are insoluble oils, polydimethylsiloxanes and other silicones, certain alcohols, stearates and glycols.
Anti-foam additive is also known as defoamer or foam inhibitor.
Corrosionpedia explains Anti-Foam Additive
Anti-foam additive is used to prevent formation of foam or to break up foam already formed. Its use also minimizes the likelihood of fuel splashing on the ground or onto clothing, avoiding the nuisance of stains and unpleasant odor, and reducing the risk of spills polluting the ground and the atmosphere.
Anti-foam additives are common in many types of lubricating oils and hydraulic fluids. It is normally used in diesel fuel and industrial processes to increase speed and reduce other problems. It addresses both problems with surface foam and entrained or entrapped air. Foaming can disrupt key refinery process units, reducing run times and degrading the operation of sensitive downstream equipment.
Foam-causing air bubbles create a variety of problems in oil. They make oil harder to pump to vital engine parts, reduce the oil's lubrication effectiveness and inhibit the oil's ability to help keep the engine cool. Foamy oil can result in serious engine damage. An anti-foam additive helps prevent these problems, specifically at high temperatures.
Foams can cause defects on surface coatings in industrial processes and prevent the efficient filling of containers. Foaming not only enhances oil oxidation but also decreases lubrication effects, causing oil starvation.
Diesel fuel has a natural tendency to entrain air and form temporary foam when dispensed from a filling station. Foaming is a particular problem for diesel passenger cars, which employ tanks of irregular shapes and narrow filler pipes. With automatic cut-off dispenser systems, which are now almost universal, foaming leads to premature fuel cut-off and a partially filled tank. Anti-foam additives effectively eliminate these concerns. It functions by reducing the surface tension of the air bubble walls which constitute the foam, leading to its rapid collapse.