Claims
- 1. A method for chemically dislodging deposits from the internal components of a gas turbine engine, while preserving the alloys or coatings used therein, said method comprising the steps of:
- (a) contacting said deposits on said components with a cleaning composition comprising an aqueous solution of 0.1-2.0 molar hydroxylamine sulfate, a chelating agent, 0.1-4.0 molar concentration of a compound selected from the group consisting of ammonium sulfamate, sulfamide and hydroxylamine-o-sulfonic acid, and, an alkaline pH modifying substance added in an amount sufficient to achieve a pH value of from 6.5 to 14, thereby chemically dislodging said deposits from said components; and
- (b) contacting said components with an amount of a rinse solution sufficient to remove said dislodged deposits and said cleaning composition from said engine.
- 2. The method of claim 1 wherein the cleaning composition additionally comprises up to 2.0 molar ethylenediamine.
- 3. The method of claim 1 wherein said rinse solution comprises water.
- 4. The method of claim 1 wherein, after said contacting but before said rinsing:
- (1) allowing said cleaning composition to soak into said deposits on said components; and
- (2) repeating said contacting and said soaking steps cyclically until said deposits are dislodged from said components.
- 5. The method of claim 1 wherein said cleaning composition comprises an aqueous solution of 0.4 molar hydroxylamine sulfate, 0.4 molar ethylene diamine, 0.7 molar amonium sulfamate, and 0.8 molar N-hydroxyethylenediaminetriacetic acid with ammonium hydroxide added in an amount sufficient to achieve a pH value of between 7 and 8.5.
- 6. A method for chemically dislodging deposits from the internal components of a gas turbine engine installed on an aircraft, while preserving the alloys or coatings used therein, said method comprising:
- (a) preparing a first solution of hydroxylamine sulfate and water, having a pH of less than 4;
- (b) preparing a second solution comprising a chelating agent, a compound selected from the group consisting of ammonium sulfate, sulamide, and hydroxylamine-o-sulfonic acid, and, an alkaline pH modifying substance added in an amount sufficient to achieve a pH of between 9 and 14,
- (c) mixing said first and second solutions to form a cleaning composition comprising an aqueous solution of 0.1-2.0 molar hydroxylamine sulfate, a chelating agent, 0.1-4.0 molar concentration of a compound selected from the group consisting of ammonium sulfamate, sulfamide and hydroxylamine-o-sulfonic acid, and, an alkaline pH modifying substance, said composition having a pH of between 6.5 and 14,
- (d) contacting said deposits on said components with said cleaning composition, thereby chemically dislodging said deposits from said components;
- (e) contacting said components with amounts of a rinse solution sufficient to remove said dislodged deposits and said cleaning composition from said engine, and,
- (f) drying said engine.
- 7. The method of claim 6 wherein the cleaning composition additionally comprises up to 2.0 molar ethylenediamine.
- 8. The method of claim 6 wherein said rinse solution comprises water.
- 9. The method of claim 6 wherein, after said contacting with said cleaning composition but before said rinsing;
- (a) allowing said cleaning composition to soak into said deposits on said components; and
- (b) repeating said contacting and said soaking steps cyclically until said deposits are dislodged from said compenents.
- 10. The method of claim 6 wherein said first solution comprises an aqueous solution of about 0.8 molar hydroxylamine sulfate, having a pH of from 3-4; said second solution comprises an aqueous solution of about 1.4 molar ammonium sulfate, about 1.6 molar N-hydroxyethylethyenediaminetriacetic acid with ammonium hydroxide added in an amount sufficient to achieve a pH of between 9 and 10; and, said cleaning composition comprises an aqueous solution of about 0.4 molar hydroxylamine sulfate, about 0.4 molar ethylenediamine, about 0.7 molar ammonium sulfate, and about 0.8 molar N-hydroxyethylethyenediaminetriacetic acid with ammonium hydroxide added in an amount sufficient to achieve a pH value of between 7 and 8.5.
Government Interests
The Government has rights in the invention pursuant to Contract No. F33657-84-C-2122 awarded by the Department of the Air Force.
US Referenced Citations (20)