US4728452A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Metal corrosion inhibition in closed cooling systems
Assignee: Pony Industries Inc
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Filing: 1986-01-17
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Granted: 1988-03-01
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Expires: 2006-01-17
Abstract
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.
Inventors
- 👤 Gerald D. Hansen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 14:56
CPC Classifications
C; C23; C23F; C23F11/00; C23F11/08; C09; C09K; C09K5/00; C09K5/20
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
105 words
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.
Claim 2
Dependent Claim
105 words
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.
Claim 3
Dependent Claim
26 words
The coolant composition of claim 1 additionally containing a freezing point depressing amount of at least one alcohol, at least one glycol or a mixture thereof.
Claim 4
Dependent Claim
24 words
The coolant composition of claim 2 wherein the alcohol, glycol or mixed alcohol-glycol component comprises about 40% to 80% by weight of the coolant.
Claim 5
Dependent Claim
34 words
The coolant composition of claim 1 wherein the nitrite is sodium nitrite, the nitrate is sodium nitrate, the azole is sodium tolyltriazole, sodium mercaptobenzothiazole or a mixture thereof, and the molybdate is sodium molybdate.
Claim 6
Dependent Claim
28 words
In a process for inhibiting the corrosion of metals in constant contact with an aqueous coolant, the improvement wherein said aqueous coolant comprises the composition of claim 1.
Claim 7
Dependent Claim
28 words
In a process for inhibiting the corrosion of metals in constant contact with an aqueous coolant, the improvement wherein said aqueous coolant comprises the composition of claim 4.
Claim 8
Dependent Claim
34 words
A cooling system comprising the metal corrosion inhibited coolant composition of claim 1, and an apparatus for containing and transporting said composition, wherein said apparatus includes a metal surface in contact with said composition.
Claim 9
Dependent Claim
12 words
The cooling system of claim 7, wherein said metal surface includes aluminum.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-03-01 | 1991-08-31 | 1992-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-03-01 | 1995-08-31 | 1996-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-03-01 | 1999-08-31 | 2000-03-01 | $7700.00 | Window Closed / Lapsed |