Patent US4120818A successfully refreshed from Google Patents.
US4120818A
Expired / Lapsed
US
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Irreversible warmup indicator
Assignee: United States Department of the Army
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Filing: 1976-08-10
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Granted: 1978-10-17
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Expires: 1996-08-10
Abstract
Abstract A device for indicating irreversibly by means of color change that temperatures equal to or above 7 DEG C, 10 DEG C, or 13 DEG C have occurred. A container which has an orifice therein is filled with a liquid which freezes at the temperature to be monitored. A dye is dissolved in the liquid. The orifice is placed in proximity to an indicating paper. When the container is activated by freezing, any increase in temperature after activation causes the liquid to melt, expand and escape through the orifice contacting the indicating paper thereby dying the paper and producing an irreversible signal.
Inventors
- 👤 Frank E. Swindells
- 👤 Mary G. Klimas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:35
CPC Classifications
G; G01; G01N; G01N33/00; G01N33/02; G01K; G01K11/00; G01K11/06; Y; Y10; Y10S; Y10S252/00; Y10S252/962
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
153 words
An irreversible warmup indicator comprising: a. gelatin capsule having a seam therein; b. a strip of indicating paper-aluminum foil laminate covering one-half of the circumference of the capsule with the aluminum side of the laminate in contact with the capsule; c. a sealed glass tube containing said capsule and said laminate; d. a plastic outer casing containing said sealed glass tube; e. a liquid placed in said capsule with a melting point which is equal to the temperature to be monitored, said liquid having a positive thermal expansion coefficient in the temperature range immediately above its freezing point, whereby the apparatus is activated by freezing the liquid and a subsequent temperature rise causes thawing of the liquid, which expands and escapes through the seam in the capsule and contacts the indicating paper; and f. a dye, which is either dissolved in said liquid or is placed in powder form on said indicating paper.
Claim 2
Dependent Claim
153 words
An irreversible warmup indicator comprising: a. gelatin capsule having a seam therein; b. a strip of indicating paper-aluminum foil laminate covering one-half of the circumference of the capsule with the aluminum side of the laminate in contact with the capsule; c. a sealed glass tube containing said capsule and said laminate; d. a plastic outer casing containing said sealed glass tube; e. a liquid placed in said capsule with a melting point which is equal to the temperature to be monitored, said liquid having a positive thermal expansion coefficient in the temperature range immediately above its freezing point, whereby the apparatus is activated by freezing the liquid and a subsequent temperature rise causes thawing of the liquid, which expands and escapes through the seam in the capsule and contacts the indicating paper; and f. a dye, which is either dissolved in said liquid or is placed in powder form on said indicating paper.
Claim 3
Dependent Claim
13 words
The apparatus as described in claim 1 wherein said liquid is ethyl cinnamate.
Claim 4
Dependent Claim
13 words
The apparatus as described in claim 1 wherein said liquid is dimethyl adipate.
Claim 5
Dependent Claim
13 words
The apparatus as described in claim 1 wherein said liquid is ethyl anthranilate.
Claim 6
Dependent Claim
15 words
The apparatus as described in claim 1 wherein a dye is dissolved in said liquid.
Claim 7
Dependent Claim
30 words
The apparatus as described in claim 1 wherein said indicating paper is impregnated with a dry dye soluble in said liquid, said dry dye mixed with an inert white pigment.
Claim 8
Dependent Claim
15 words
The apparatus as described in claim 6 wherein said inert white pigment is titanium dioxide.
Claim 9
Dependent Claim
16 words
The apparatus as described in claim 2 wherein a dye is dissolved in the ethyl cinnamate.
Claim 10
Dependent Claim
16 words
The apparatus as described in claim 3 wherein a dye is dissolved in the dimethyl adipate.
Claim 11
Dependent Claim
16 words
The apparatus as described in claim 4 wherein a dye is dissolved in the ethyl anthranilate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-10-16 | 1982-04-17 | 1982-10-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-16 | 1986-04-17 | 1986-10-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-16 | 1990-04-17 | 1990-10-17 | $7700.00 | Window Closed / Lapsed |