Anti-foam agent

Foams are used industrially and are important in rubber preparations (foamed-latex) and in fire fighting. The foam floats as a continuous layer across the burning surface, so preventing the evolution of inflammable vapours. Foams are also used in gas absorption and in the separation of proteins from biological fluids. See anti-foaming agents. 

Anti-foaming agents polydimethylsiloxanes, fluorosilicones, acrylates. 

In addition, buffer salts such as disodium hydrogen phosphate may be used to prevent the pH of the aqueous phase falling during polymerisation. Small amounts of an anti-foam agent may be employed to reduce frothing when discharging from the vessel at the end of the polymerisation process. 

The coal-water mixture fed to the boilers has to be formulated to a certain specification. This is done with the proper inclusion of additives to facilitate combustion. The recommended additives include a petroleum-based surfactant (polysulfones or polycar-boxylates), a stabilizing (e.g. xanthan gum), a biocide and an anti-foaming agent (such as a silicone base). 

An atomic absorption method was published by AOAC Int. (2000) for determination of the anti-foaming agent polydimethylsiloxane in pineapple juice, that is based on extraction with 4-methyl-2-pentanone and aspiration into a nitrous oxide/acetylene flame. A silicone lamp was used for detection. 

Anti-foaming agent Antioxidant Substance which prevents or reduces foaming Substance which prolongs the shelf life of foodstuffs by protecting them against deterioration caused by oxidation, such as fat rancidity and colour changes... 

Anti-foaming agent Antioxidant Bulking agent... 

Anti-foaming Agent 900 Dimethyl polysiloxane 1.5 25th p 18 648, p 31, 1980... 

Anti-foaming Agent 1521 Polyethylene glycol 6000 Ace 36th 648, p 17, 1980... 

Fluorad fC-120 fIuorochemical surfactant SWS-211 silicone anti foam agent Ektasolve DE glycol ether Ektasolve DM glycol ether Texanol ester alcohol... 

Although they were effective in reducing toam heights, the Dixon plates were nut effective enough to allow operation without the injection of an anti-foam agent. 

The foaming tendency of Ninian dead crude is high compared with other crudes To eliminate foaming, a high molecular-weight anti foam agent-polydimethyl siloxane (60,000-cSt [60 000-mmJ s] silicone oil>—was injected into the crude. 

To ensure that the anti-foam agent was adequately mixed, it was injected upstream of the dehydrators. Thus, an existing demulsifier injection unit with the necessary feed tank and metering pumps could be used temporarily... 

Experiments with different injection rates were conducted The results indicated that the effective concentration of anti-foam agent to be added to the LP separators was 1.5 ppm by volume in the crude. 

Because injection of anti-foam agent would probably he a permanent requirement, a scheme to provide dedicated anti-foam injection facilities for both Ninian and Brent crude streams was prepared. 

Brent System. Experiments also showed that Brent crude would foam, although the foam was less stable and broke down more quickly than Ninian crude foam. This was borne out by plant experience. Again, a conventional 60.000 cSt 60 000 mm2/sj silicone oil proved to be a very effective anti-foam agent. 

To maintain control of foaming in both separators, an increase in the dosage rate of anti-foam agent to 2.5 ppm by volume in the crude was necessary,... 

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