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US 4,728,452 AGranted
Metal corrosion inhibition in closed cooling systems
AssigneePony Industries, Inc.
InventorGerald D. Hansen
Life of this patent
Estimating the term…
Abstract
The corrosion of metals in closed, aqueous cooling systems having a pH of 7.5 to 10.5 is inhibited by adding to the system a coolant concentrate comprising water, at least 10% by weight of a water soluble nitrite or a mixture of a water soluble nitrite and a water soluble nitrate, 0.2 to 2.0% by weight of at least one water soluble azole, and 0.1 to 1.0% by weight of a water soluble molybdate, to provide in the system concentrations of at least 200 ppm of the nitrite or nitrite/nitrate mixture, 2 to 20 ppm of the azole and 1 to 10 ppm of the molybdate.
Claims8
A metal corrosion inhibited coolant composition, comprising:
- (1) a water-soluble nitrite or a mixture of a water-soluble nitrite and a water-soluble nitrate, a water-soluble azole selected from triazoles, thiazoles and mixtures of these and a water-soluble molybdate,
- (2) sufficient dilution water to provide from about 200 to about 500 ppm of nitrite or mixture of nitrite and nitrate, from about 2 to about 8 ppm azole and from about 2 to about 10 ppm molybdate, and
- (3) a buffer present in said composition in an amount sufficient to maintain the pH of said composition to between about 7.5 and 10.5;
- wherein said composition is silicate-free.
1 more element
Dependencies are inferred from the claim text.