Patent US4019865A successfully refreshed from Google Patents.
US4019865A
Expired / Lapsed
US
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H2 S indicator
Assignee: 3M Co
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Filing: 1976-02-13
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Granted: 1977-04-26
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Expires: 1996-02-13
Abstract
Abstract The prolonged attainment of high concentrations of H 2 S in a gaseous environment is indicated by a device which comprises a base, an enclosing upper surface which is transparent and water impenetrable, and a light stable composition enclosed by the base and upper surface, said composition undergoing a visible change in color or tone when exposed to a constant concentration of 1 part per million of H 2 S for one day.
Inventors
- 👤 Robin A. Sinclair
- 👤 Eileen A. Glasspoole
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 17:03
CPC Classifications
G; G01; G01N; G01N31/00; G01N31/22; G01N31/223; G01N31/224
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
166 words
A device for indicating the prolonged attainment within a gaseous environment of a concentration of H 2 S sufficient to tarnish free metal silver in said environment before tarnishing of said free metal silver comprising: 1. a base support surface, 2. an upper surface which is not water penetrable forming at least an enclosed volume with said support surface, said upper surface having a translucent or transparent portion exposing at least a part of said enclosed volume and allowing penetration of vapor through said upper surface so that penetrating vapor will contact: 3. a light-stable composition within said enclosed volume which undergoes a visible light-stable change which is a change in tone or color or intensification of its tone or color when reacted with H 2 S, said composition undergoing said visible change within 1 day when exposed to a constant concentration of 1 part per million of H 2 S, and said composition in said enclosed volume having free vapor access to its surrounding environment.
Claim 2
Independent Claim
166 words
A device for indicating the prolonged attainment within a gaseous environment of a concentration of H 2 S sufficient to tarnish free metal silver in said environment before tarnishing of said free metal silver comprising: 1. a base support surface, 2. an upper surface which is not water penetrable forming at least an enclosed volume with said support surface, said upper surface having a translucent or transparent portion exposing at least a part of said enclosed volume and allowing penetration of vapor through said upper surface so that penetrating vapor will contact: 3. a light-stable composition within said enclosed volume which undergoes a visible light-stable change which is a change in tone or color or intensification of its tone or color when reacted with H 2 S, said composition undergoing said visible change within 1 day when exposed to a constant concentration of 1 part per million of H 2 S, and said composition in said enclosed volume having free vapor access to its surrounding environment.
Claim 3
Dependent Claim
30 words
The device of claim 1 wherein the visible change is from colorless to colored or from white to a color or tone having an optical density of at least 0.2.
Claim 4
Dependent Claim
33 words
The device of claim 1 wherein said composition will undergo said visible change within 1 day when exposed to a constant concentration of less than 50 parts per billion of H 2 S.
Claim 5
Dependent Claim
33 words
The device of claim 1 wherein said composition will undergo said visible change within 1 day when exposed to a constant concentration of less than 2 parts per billion of H 2 S.
Claim 6
Dependent Claim
50 words
The device of claim 1 in combination with an absorbent for H 2 S which has a static equilibrium vapor pressure with H 2 S which is at most one-tenth the constant concentration level of H 2 S at which the composition will undergo said visible change within 1 day.
Claim 7
Dependent Claim
49 words
The device of claim 1 in combination with an absorbent for H 2 S which has a static equilibrium vapor pressure with H 2 S which is at most one-hundredth constant concentration level of H 2 S at which the composition will undergo said visible change within 1 day.
Claim 8
Dependent Claim
23 words
The device of claim 1 wherein the composition within said volume is a solution of a transition metal salt other than a sulfide.
Claim 9
Dependent Claim
15 words
The device of claim 7 wherein the solvent of said solution is a polyhydric alcohol.
Claim 10
Dependent Claim
13 words
The device of claim 7 wherein the salt is a transition metal nitrate.
Claim 11
Dependent Claim
15 words
The device of claim 9 wherein the solvent of said solution is a polyhydric alcohol.
References Cited (Backward Citations)
US3223487A
Cited
US3715192A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-04-25 | 1980-10-25 | 1981-04-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-25 | 1984-10-25 | 1985-04-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-25 | 1988-10-25 | 1989-04-26 | $7700.00 | Window Closed / Lapsed |