US4107993A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for level measurement using microwaves
Assignee: Monsanto Co
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Filing: 1975-12-29
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Granted: 1978-08-22
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Expires: 1995-12-29
Abstract
Abstract Microwaves are used to detect the level of a liquid in a vessel. An external chamber, constructed of a material essentially invisible to microwaves, is connected to the vessel and is open to the interior of the vessel above and below the level to be detected. Microwaves are directed through the external chamber and the unabsorbed energy of the microwaves passing through the external chamber is measured and converted to a signal representative of the liquid level in the vessel. Known electrical circuitry is used to generate the microwaves, to measure the unabsorbed microwave energy, and to convert the measured energy to a standard instrument signal representative of the liquid level in the vessel.
Inventors
- 👤 Thomas J. Shuff
- 👤 Robert W. Sims
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:02
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
39 words
The method of continuously indicating the level of a liquid in a vessel comprising: generating microwaves, directing the microwaves through said vessel, measuring the unabsorbed microwave energy, and determining the level of the liquid from said unabsorbed microwave energy.
Claim 2
Independent Claim
39 words
The method of continuously indicating the level of a liquid in a vessel comprising: generating microwaves, directing the microwaves through said vessel, measuring the unabsorbed microwave energy, and determining the level of the liquid from said unabsorbed microwave energy.
Claim 3
Independent Claim
67 words
The method of continuously indicating the level of a liquid in a vessel comprising: simulating the level of liquid in the vessel in a means essentially invisible to microwaves having a cross-section of one-half inch or less attached to said vessel, generating microwaves, directing the microwaves through said simulator means, measuring the unabsorbed microwave energy, and determining the level of the liquid from said unabsorbed microwave energy.
Claim 4
Independent Claim
67 words
The method of continuously indicating the level of a liquid in a vessel comprising: simulating the level of liquid in the vessel in a means essentially invisible to microwaves having a cross-section of one-half inch or less attached to said vessel, generating microwaves, directing the microwaves through said simulator means, measuring the unabsorbed microwave energy, and determining the level of the liquid from said unabsorbed microwave energy.
Claim 5
Independent Claim
85 words
The method of continuously indicating the level of a nonpolar liquid in a vesel comprising: creating a liquid-liquid interface by addition of a less dense polar liquid immiscible in the nonpolar liquid, simulating the interface level in the vessel in a means essentially invisible to microwaves having a cross-section of one-half inch or less attached to the vessel, generating microwaves, directing the microwaves through the similator means, measuring the unabsorbed microwave energy, and determining the level of the nonpolar liquid from the unabsorbed microwave energy.
Claim 6
Independent Claim
85 words
The method of continuously indicating the level of a nonpolar liquid in a vesel comprising: creating a liquid-liquid interface by addition of a less dense polar liquid immiscible in the nonpolar liquid, simulating the interface level in the vessel in a means essentially invisible to microwaves having a cross-section of one-half inch or less attached to the vessel, generating microwaves, directing the microwaves through the similator means, measuring the unabsorbed microwave energy, and determining the level of the nonpolar liquid from the unabsorbed microwave energy.
Claim 7
Dependent Claim
26 words
The method of claim 1 in which said generated microwaves are of a frequency between 3 gigahertz (3×10 9 Hertz) and 16.8 gigahertz (16.8×10.sup. 9 Hertz).
Claim 8
Dependent Claim
37 words
The method of claim 2 wherein said liquid is propionic acid, said means for simulating the level is constructed of glass with a diameter of 0.375 inch, and the microwave frequency is 10.525 gigahertz (10.525×10 9 Hertz).
Claim 9
Independent Claim
85 words
An apparatus for continuously indicating the level of a liquid comprising, in combination: a vessel containing said liquid, means essentially invisible to microwaves having a cross-section of one-half inch or less attached to said vessel wherein the level of said liquid is simulated, a microwave generator and means for directing the propagation of the microwaves through said simulator means, means for measuring the unabsorbed microwave energy passing through said simulator means, and means for determining the level of the liquid from said unabsorbed microwave energy.
Claim 10
Independent Claim
85 words
An apparatus for continuously indicating the level of a liquid comprising, in combination: a vessel containing said liquid, means essentially invisible to microwaves having a cross-section of one-half inch or less attached to said vessel wherein the level of said liquid is simulated, a microwave generator and means for directing the propagation of the microwaves through said simulator means, means for measuring the unabsorbed microwave energy passing through said simulator means, and means for determining the level of the liquid from said unabsorbed microwave energy.
Claim 11
Dependent Claim
32 words
Apparatus in accordance with claim 6 in which said microwave generator is an oscillator for generating microwaves of a predetermined frequency in the microwave region chosen for optimum absorption by the liquid.
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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) | 1981-08-21 | 1982-02-20 | 1982-08-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-08-21 | 1986-02-20 | 1986-08-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-08-21 | 1990-02-20 | 1990-08-22 | $7700.00 | Window Closed / Lapsed |