Patent US3766786A successfully refreshed from Google Patents.
US3766786A
Expired / Lapsed
US
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Magnetic float pycnometer
Assignee: United States Department of the Air Force
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Filing: 1971-12-02
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Granted: 1973-10-23
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Expires: 1991-12-02
Abstract
Abstract A magnetic float pycnometer system for precise measurements of liquid densities is disclosed. A float having a permanent magnet, enclosed in a closed couette, centered horizontally by the repelling action of three external magnets, is positioned vertically with respect to a light beam by the resultant forces of buoyancy acting in an upward direction, gravity acting downward, and the downward acting magnetic force resulting from the interaction of the magnetic field from the magnet in the float and the magnetic field created by a current in an external solenoid. Vertical stability is achieved by operating the float magnet at or near the point of inflection of the magnetic field of the solenoid where a decreasing force with decreasing displacement of the float from the solenoid exists. The magnitude of the current in the solenoid to position the float is a relative measure of the density of the fluid in the couette.
Inventors
- 👤 D Wiff
- 👤 M Gehatia
- 👤 K Leinberger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:14
CPC Classifications
G; G01; G01N; G01N9/00; G01N9/10; G01N9/20
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
343 words
A magnetic float pycnometer for measuring the relative density of a liquid contained in a transparent couette, comprising: a. a float having an opaque section position in the said couette; b. a permanent magnet having a predetermined length, positioned within the said float such that the center of buoyancy of the float is above the center of gravity. c. means for providing a light beam in partial intercepting relationship with the said opaque section of the float; d. a photocell providing an electrical output for receiving that portion of the said light beam not intercepted by the float; e. a current meter cooperating with the output of the said photocell for indicating the position of the float with respect to the said light beam; f. means, including a force coil, for providing a magnetic field having a force of attraction and a force of repulsion on the said float magnet, the said magnetic field having external to the said coil an axial magnetic field density which, on a flux density vs. distance plot provides a point of inflection approximately equal distant from two points of equal slope, the said points of equal slope being spaced apart a distance approximately equal to the said predetermined length of the permanent magnet; g. means including a voltage source and a calibrated variable resistance cooperating with the said force coil for manually setting a determined force on the float magnet to position the float to a predetermined position with respect to the said light beam, such that the center of the said permanent magnet is located approximately at the said point of inflection; h. a feedback amplifier responsive to the output of the said photocell, cooperating with the said force coil, and the said voltage source and calibrated variable resistance, for maintaining the said determined force on the float magnet; and i. a plurality of permanent magnets, positioned exterior the said couette in repelling relationship to the said float magnet, for reducing the effects of external magnetic fields and providing horizontal centering of the said float magnet.
Claim 2
Dependent Claim
343 words
A magnetic float pycnometer for measuring the relative density of a liquid contained in a transparent couette, comprising: a. a float having an opaque section position in the said couette; b. a permanent magnet having a predetermined length, positioned within the said float such that the center of buoyancy of the float is above the center of gravity. c. means for providing a light beam in partial intercepting relationship with the said opaque section of the float; d. a photocell providing an electrical output for receiving that portion of the said light beam not intercepted by the float; e. a current meter cooperating with the output of the said photocell for indicating the position of the float with respect to the said light beam; f. means, including a force coil, for providing a magnetic field having a force of attraction and a force of repulsion on the said float magnet, the said magnetic field having external to the said coil an axial magnetic field density which, on a flux density vs. distance plot provides a point of inflection approximately equal distant from two points of equal slope, the said points of equal slope being spaced apart a distance approximately equal to the said predetermined length of the permanent magnet; g. means including a voltage source and a calibrated variable resistance cooperating with the said force coil for manually setting a determined force on the float magnet to position the float to a predetermined position with respect to the said light beam, such that the center of the said permanent magnet is located approximately at the said point of inflection; h. a feedback amplifier responsive to the output of the said photocell, cooperating with the said force coil, and the said voltage source and calibrated variable resistance, for maintaining the said determined force on the float magnet; and i. a plurality of permanent magnets, positioned exterior the said couette in repelling relationship to the said float magnet, for reducing the effects of external magnetic fields and providing horizontal centering of the said float magnet.
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) | 1976-10-22 | 1977-04-23 | 1977-10-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-22 | 1981-04-23 | 1981-10-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-22 | 1985-04-23 | 1985-10-23 | $7700.00 | Window Closed / Lapsed |