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US3696675A Expired / Lapsed US ⏱️ 0.0 years remaining

Method and means for determining liquid level in a container

Assignee: Tech Nomedic Corp
•
Filing: 1971-09-20
•
Granted: 1972-10-10
•
Expires: 1991-09-20
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Abstract

Abstract Apparatus and a method for externally determining the level of a mass of flowable material such as liquid or granular material contained in a closed or sealed container includes an elongated strip of material coated or imbedded with cholesteric liquid crystals which vary chromatically with variations in temperature. The elongated strip is applied to the outer surface of the wall of the container in heat conducting relationship thereto and extends along the height of the container. The container is exposed to a temperature change either natural, such as that which occurs at sunset and sunrise, artificially induced, such as dousing with water at a temperature different from the ambient temperature of the container or by energizing a heater element at the wall of the container adjacent the elongated strip. Because of the difference in the rate of heat conduction of the void volume and the filled space of the container, the container wall experiences a temperature gradient which is most pronounced at the interface of the contents. The temperature of the container wall changes abruptly at the surface of the contents. This change in temperature is readily discernible visually because of the abrupt change in color of the elongated strip at the material interface thus permitting an observer to readily detect the level of the contents in the container.

Inventors

  • 👤 A Scott Gilmour

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-31 15:28
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22

Claims Analysis

Total Claims: 15
Claim 1
Independent Claim 46 words
A direct reading external liquid level gauge for measuring the contents level within a container comprising an elongate strip of material including a layer of base material, a thermochromatic layer, means for securing said elongate strip of material to a container in intimate thermal contact therewith.
Claim 2
Dependent Claim 46 words
A direct reading external liquid level gauge for measuring the contents level within a container comprising an elongate strip of material including a layer of base material, a thermochromatic layer, means for securing said elongate strip of material to a container in intimate thermal contact therewith.
Claim 3
Dependent Claim 20 words
A direct reading external liquid level gauge according to claim 1 wherein said thermochromatic layer includes a liquid crystal compound.
Claim 4
Dependent Claim 16 words
A direct reading external gauge according to claim 2 wherein said liquid crystal comprises cholesteral esters.
Claim 5
Dependent Claim 20 words
A direct reading external liquid level gauge according to claim 3 wherein said thermochromatic layer includes a light absorbing background.
Claim 6
Dependent Claim 24 words
A direct reading external gauge according to claim 2 wherein the mesomorphic range of said liquid crystal lies between 15* C and 50* C.
Claim 7
Dependent Claim 17 words
A liquid level gauge according to claim 1 including means for changing the temperature of the container.
Claim 8
Dependent Claim 26 words
A liquid level gauge according to claim 6 wherein said means for changing the temperature is disposed in the area adjacent the elongate strip of material.
Claim 9
Dependent Claim 64 words
An opaque container having a liquid level gauge secured thereto on its external surface in intimate thermal contact, said gauge comprising an elongate strip of material extending height-wise of the container and spanning the interface of the contents, said elongate strip comprising a base layer and layer containing cholesteric liquid crystals, said layer containing cholesteric liquid crystals having a backing of light absorbing material.
Claim 10
Dependent Claim 64 words
An opaque container having a liquid level gauge secured thereto on its external surface in intimate thermal contact, said gauge comprising an elongate strip of material extending height-wise of the container and spanning the interface of the contents, said elongate strip comprising a base layer and layer containing cholesteric liquid crystals, said layer containing cholesteric liquid crystals having a backing of light absorbing material.
Claim 11
Dependent Claim 21 words
An opaque container according to claim 8 wherein a transparent ultra violet filter layer overlies said layer containing cholesteric liquid crystals.
Claim 12
Dependent Claim 25 words
An opaque container according to claim 8 including heater means for heating the surface of the container in the region of the liquid level gauge.
Claim 13
Independent Claim 42 words
A method for determining the level of the contents of a container which comprises applying an elongate strip of thermochromatic material to a container in intimate thermal contact spanning the interface of the contents and exposing the container to a temperature change.
Claim 14
Independent Claim 42 words
A method for determining the level of the contents of a container which comprises applying an elongate strip of thermochromatic material to a container in intimate thermal contact spanning the interface of the contents and exposing the container to a temperature change.
Claim 15
Dependent Claim 40 words
A method for determining the level of the contents of a container according to claim 11 wherein an electrically energized heater is applied to the container for inducing a temperature change in the region of the interface of the contents.

References Cited (Backward Citations)

US3533399A Cited
US3479875A Cited
US3617374A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1975-10-10 1976-04-10 1976-10-10 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1979-10-10 1980-04-10 1980-10-10 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1983-10-10 1984-04-10 1984-10-10 $7700.00 Window Closed / Lapsed

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