Defoamer

A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam in industrial process liquids.

Commonly used agents are insoluble oils, polydimethylsiloxanes and other silicones, certain alcohols, stearates and glycols.

[1] Generally a defoamer is insoluble in the foaming medium and has surface active properties.

An essential feature of a defoamer product is a low viscosity and a facility to spread rapidly on foamy surfaces.

Silicone oils worked well, but caused surface disturbances in many applications like paints and papermaking.

In the early 1970s, hydrophobic waxes like ethylene bis stearamide dispersed in oils developed.

In the early 1990s, silicone emulsion defoamers that caused less surface disturbance were used in the wood pulping industry with great success.

[5] These are also heavy duty defoamers and are good at both knocking down surface foam and releasing entrained air.

Alkyl polyacrylates are suitable for use as defoamers in non-aqueous systems where air release is more important than the breakdown of surface foam.

Surface foam may cause problems with liquid levels and give overflow leading to pools of oils around the equipment which is a safety concern.

If these small bubbles have sufficient buoyancy, they can rise to the surface and together form foam.

Mechanical factors that may generate entrapped air: Foam, entrained and dissolved air that are present in coolants and processing liquids, may cause various kinds of problems, including: There are several ways to test defoamers.

Defoamer is added into the recovery tank of carpet extractors to prevent too much-foaming damage to the vac motor.

When used as an ingredient in food, antifoaming agents are intended to curb effusion or effervescence in preparation or serving.

[citation needed] The agents are included in a variety of foods and in materials for food preparation; McDonald's includes polydimethylsiloxane (a type of silicone) in its oil to mitigate hazardous splashes of oil caused by foaming in fryers,[7] so it has been listed as an ingredient in their chicken nuggets, french fries, and other fried menu items.