US 6,183,649 B2Granted

Method for treating water circulating systems

OwnerMichael W. Fontanainventor

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Abstract

Water-circulating systems are treated with an aqueous, alkaline composition comprising I) an organo-phosphorus chelating agent, II) an acrylate homopolymer, III) a salt of an acrylic copolymer, a portion of the repeating units of which contain sulfonate groups, IV) a molybdate salt, and V) a salt of a fused-ring aromatic triazole. This composition (which is formulated in accordance with a specific order of addition of the ingredients) is effective against white rust (corrosion of galvanized metal parts). When the water-circulating system is also fouled with a biofilm, it is preferred to introduce a biofilm remover having biocidal, surfactant, and chelating properties into the system, but the biofilm remover is introduced separately from the above-described composition. The preferred biofilm removers are compounds of the formula R—S—A—NR1R2 where R is an aliphatic group having at least 8 carbon atoms, A is an alkylene group having 1 to 6 carbon atoms, R1 and R2 are the same or different and are hydrogen or an aliphatic group, or R1 and R2, together with the nitrogen of formula I, form a heterocyclic aliphatic group.

Claims6

Dependent claims

A method for treating a water-circulating system and preventing, inhibiting and/or removing white rust, comprising the step of treating the water in said system with a composition comprising:

I) R3(COOM)3(PO3M′2) wherein R3 is an aliphatic group having 3 carbon atoms, M and M′ are the same or different and are hydrogen or an alkali metal,
II) an alkali metal polyacrylate homopolymer,
III) a polymer containing alkali metal salt units of the following formulas:
—(—CH2—C[R4][COOM″]—)—,
wherein R4 through R8 are the same or different and are alkyl groups of 1 to 4 carbon atoms, Ar is an aromatic ring, and the M″ cations, which can be the same or different, are alkali metal cations,
IV) alkali metal molybdate,
V) an alkali metal salt of unsubstituted or substituted 1-H-benzotriazole, wherein the fused benzene ring of the benzotriazole is optionally substituted with a least one alkyl group of 1 to 4 carbon atoms,
VI) optionally, an alkali metal bromide, and
VII) optionally, sufficient alkali metal hydroxide to raise the pH of said composition to about 10.5 to about 12, and sufficient water to provide an aqueous solvent medium for the components of said composition
wherein the water circulating system includes metallic elements, and wherein at least one metallic element comprises galvanized metal, and wherein said composition is brought into contact with the galvanized metal, and thereby preventing, inhibiting and/or removing white rust.

7 more elements

Dependencies are inferred from the claim text.