US4396436A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and flushing for removing hydraulic fluid from hydraulic systems
Assignee: ALUMIUM Co OF AMERICA PITTSBURGH PA A CORP OF
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Filing: 1981-07-20
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Granted: 1983-08-02
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Expires: 2001-07-20
Abstract
Abstract A method for removing residual hydraulic fluid from hydraulic systems employing a flushing fluid comprising a thickening agent dissolved in an organic solvent having a boiling point below about 125° C. After draining fluid from a hydraulic system, flushing fluid is injected into the system and circulated to dissolve residual fluid. The flushing fluid, containing dissolved residual fluid, is then drained from the system. In a preferred embodiment, the flushing fluid comprises about one to three percent by weight ethyl cellulose dissolved in 1,1,1-trichloroethane together with about 0.1 to six percent by weight of a friction-reducing antiwear additive.
Inventors
- 👤 Joseph T. Laemmle
- 👤 William E. Boren
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 09:47
CPC Classifications
B; B08; B08B; B08B3/00; B08B3/04; B08B3/08; C; C11; C11D; C11D7/00; C11D7/50; C11D7/5004; C11D7/5018; Y; Y10; Y10T; Y10T137/00; Y10T137/0318; Y10T137/0402; Y10T137/0419
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
95 words
A method for flushing residual hydraulic fluid from a hydraulic system, comprising the steps of (a) draining hydraulic fluid from the system; (b) injecting into the system an organic solution comprising a thickening agent of ethyl cellulose dissolved in an organic solvent of chlorinated hydrocarbon having a boiling point below about 125° C., said hydraulic fluid being soluble in said organic solution; (c) circulating the organic solution through the system under an elevated pressure above atmospheric by pumping to dissolve any residual hydraulic fluid contained therein; and (d) draining the organic solution from the system.
Claim 2
Independent Claim
95 words
A method for flushing residual hydraulic fluid from a hydraulic system, comprising the steps of (a) draining hydraulic fluid from the system; (b) injecting into the system an organic solution comprising a thickening agent of ethyl cellulose dissolved in an organic solvent of chlorinated hydrocarbon having a boiling point below about 125° C., said hydraulic fluid being soluble in said organic solution; (c) circulating the organic solution through the system under an elevated pressure above atmospheric by pumping to dissolve any residual hydraulic fluid contained therein; and (d) draining the organic solution from the system.
Claim 3
Dependent Claim
20 words
The method of claim 1 further comprising (e) evaporating the organic solvent from the organic solution recovered in step (d).
Claim 4
Dependent Claim
18 words
The method of claim 2 further comprising (f) recycling to step (b) organic solvent recovered in step (e).
Claim 5
Dependent Claim
24 words
The method of claim 1 wherein said thickening agent consists essentially of ethyl cellulose having an ethoxyl content greater than about 49% by weight.
Claim 6
Dependent Claim
20 words
The method of claim 1 wherein said thickening agent is present in an amount less than about 10% by weight.
Claim 7
Dependent Claim
22 words
The method of claim 5 wherein said thickening agent is present in an amount of about one to three percent by weight.
Claim 8
Dependent Claim
19 words
The method of claim 1 wherein said organic solvent has a boiling point of about 40° to 100° C.
Claim 9
Dependent Claim
20 words
The method of claim 1 wherein said organic solvent is selected from the group consisting of 1,1,1-trichloroethane, tetrachloroethene and trichloromethane.
Claim 10
Dependent Claim
11 words
The method of claim 8 wherein said organic solvent is 1,1,1-trichloroethane.
Claim 11
Dependent Claim
21 words
The method of claim 1 wherein said organic solution further comprises about 0.1 to 6% by weight of a friction-reducing additive.
Claim 12
Dependent Claim
70 words
A solution useful, as a flushing fluid for hydraulic systems, said solution comprising (a) a chlorinated hydrocarbon solvent having a boiling point below about 125° C. for hydraulic fluid; (b) an organic polymeric thickening agent of ethyl cellulose dissolved in said solvent in an amount less than about 10% by weight of said solution; and (c) about 0.1 to 6% by weight of a friction-reducing additive soluble in said solvent.
Claim 13
Dependent Claim
70 words
A solution useful, as a flushing fluid for hydraulic systems, said solution comprising (a) a chlorinated hydrocarbon solvent having a boiling point below about 125° C. for hydraulic fluid; (b) an organic polymeric thickening agent of ethyl cellulose dissolved in said solvent in an amount less than about 10% by weight of said solution; and (c) about 0.1 to 6% by weight of a friction-reducing additive soluble in said solvent.
Claim 14
Dependent Claim
11 words
The solution of claim 11 wherein said organic solvent is 1,1,1-trichloroethane.
Claim 15
Dependent Claim
21 words
The solution of claim 11 wherein said thickening agent is ethyl cellulose having an ethoxyl content greater than 49% by weight.
Claim 16
Dependent Claim
12 words
Claim 9 or claim 12 wherein said hydraulic fluid comprises polychlorinated biphenyl.
Claim 17
Dependent Claim
12 words
Claim 10 or claim 13 wherein said friction-reducing additive comprises zinc dithiophosphate.
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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) | 1986-08-01 | 1987-01-31 | 1987-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-01 | 1991-01-31 | 1991-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-01 | 1995-01-31 | 1995-08-02 | $7700.00 | Window Closed / Lapsed |