US4145918A — Freeze-thaw indicator

Claim 1

Independent Claim 165 words

A device for indicating that an environment has reached or passed through the temperature near a freezing point of a liquid comprising: a frangible sealed ampul, a liquid being enclosed in said ampul, said liquid having the characteristic of expanding in volume at or near its freezing point, said ampul having at least a first and a second face, said first face having an indentation projecting relatively close to but spaced from said second face inside of said ampul, said indentation forming a sharp acute angle inside of said ampul, said indentation performing the dual function of providing a site for encouraging crystal growth when said liquid is at or near its freezing point and further providing a mechanism for strengthening said first face of said ampul relative to said second face whereby said frangible, sealed ampul will consistently break upon the expansion of said liquid, thereby indicating that the environment has reached or passed through a temperature near the freezing point of said liquid.

Claim 2

Independent Claim 165 words

A device for indicating that an environment has reached or passed through the temperature near a freezing point of a liquid comprising: a frangible sealed ampul, a liquid being enclosed in said ampul, said liquid having the characteristic of expanding in volume at or near its freezing point, said ampul having at least a first and a second face, said first face having an indentation projecting relatively close to but spaced from said second face inside of said ampul, said indentation forming a sharp acute angle inside of said ampul, said indentation performing the dual function of providing a site for encouraging crystal growth when said liquid is at or near its freezing point and further providing a mechanism for strengthening said first face of said ampul relative to said second face whereby said frangible, sealed ampul will consistently break upon the expansion of said liquid, thereby indicating that the environment has reached or passed through a temperature near the freezing point of said liquid.

Claim 3

Dependent Claim 34 words

A device as set forth in claim 1 further including an indicator material in proximity to said ampul, said indicator material being responsive to the release of said liquid when said container is broken.

Claim 4

Dependent Claim 24 words

A device as set forth in claim 2 wherein said indicator material is a strip of paper having a dye impregnated on one side.

Claim 5

Dependent Claim 19 words

A device as set forth in claim 1 further including a housing, said housing protecting said frangible sealed ampul.

Claim 6

Dependent Claim 15 words

A device as set forth in claim 4 wherein said housing is substantially hermetically sealed.

Claim 7

Dependent Claim 19 words

A device as set forth in claim 5 wherein one side of said housing is a preformed blister pack.

Claim 8

Dependent Claim 22 words

A device as set forth in claim 6 wherein said blister pack includes at least one embossment for protecting said frangible container.

Claim 9

Dependent Claim 30 words

A device as set forth in claim 6 further including another side of said housing, said other side including a layer of metallized foil for conducting heat from said housing.

Claim 10

Dependent Claim 17 words

A device as set forth in claim 1 wherein said frangible sealed ampul includes a glass ampul.

Claim 11

Dependent Claim 23 words

A device as set forth in claim 9 wherein said ampul is at least 91.5% by volume filled with a liquid including water.

Claim 12

Dependent Claim 22 words

A device as set forth in claim 10 further including a nucleating agent contained in said liquid for promoting ice crystal growth.

Claim 13

Dependent Claim 15 words

A device as set forth in claim 11 wherein said nucleating agent is silicon carbide.

Claim 14

Dependent Claim 14 words

A device as set forth in claim 9 wherein said ampul is heat sealed.

Claim 15

Dependent Claim 16 words

A device as set forth in claim 9 wherein said ampul is sealed by silicone rubber.

Claim 16

Dependent Claim 24 words

A device as set forth in claim 1 wherein said ampul has a volume substantially greater at one end than at the other end.

Claim 17

Dependent Claim 23 words

A device as set forth in claim 15 wherein said one end of said ampul is substantially in the shape of a disc.

Claim 18

Dependent Claim 22 words

An ampul as set forth in claim 1 wherein said at least one indentation is in the shape of a longitudinal wedge.

Claim 19

Dependent Claim 14 words

An ampul as set forth in claim 1 wherein said ampul is heat sealed.

Claim 20

Independent Claim 139 words

A device for use with a freeze or thaw indicator comprising: an ampul adapted to be at least partially filled with a liquid which undergoes volume expansion when its temperature passes below its freezing point; said ampul including a disc shaped portion and a narrow cylindrical portion integral with said disc shaped portion, one side of said disc shaped portion having at least one indentation projecting into the inside of said ampul relatively close to but spaced from the side opposite said one side of said disc shaped portion, said indentation forming a sharp, acute angle inside of said ampul wherein said one side is made stronger than said opposite side of said disc shaped portion and crystal growth is encouraged at said sharp, acute angle in said indentation, whereby said ampul will normally break at a predetermined temperature.

Claim 21

Independent Claim 139 words

A device for use with a freeze or thaw indicator comprising: an ampul adapted to be at least partially filled with a liquid which undergoes volume expansion when its temperature passes below its freezing point; said ampul including a disc shaped portion and a narrow cylindrical portion integral with said disc shaped portion, one side of said disc shaped portion having at least one indentation projecting into the inside of said ampul relatively close to but spaced from the side opposite said one side of said disc shaped portion, said indentation forming a sharp, acute angle inside of said ampul wherein said one side is made stronger than said opposite side of said disc shaped portion and crystal growth is encouraged at said sharp, acute angle in said indentation, whereby said ampul will normally break at a predetermined temperature.

Claim 22

Dependent Claim 16 words

An ampul as set forth in claim 19 wherein said ampul is sealed by silicone rubber.

Claim 23

Dependent Claim 17 words

An ampul as set forth in claim 19 wherein said ampul is made of a frangible glass.

Claim 24

Dependent Claim 20 words

An ampul as set forth in claim 19 wherein said ampul is substantially filled with a liquid which includes water.

Claim 25

Dependent Claim 18 words

An ampul as set forth in claim 22 further including a nucleating agent for promoting ice crystal growth.

Claim 26

Dependent Claim 15 words

An ampul as set forth in claim 26 wherein said nucleating agent is silicon carbide.

Claim 27

Dependent Claim 23 words

An ampul as set forth in claim 22 wherein said water is filled to include at least 95% by volume of said container.

Claim 28

Dependent Claim 36 words

An ampul as set forth in claim 19 wherein a portion of the inner surface of said ampul is etched for providing a place for crystal growth at or near the freezing point of said liquid.

Claim 29

Dependent Claim 113 words

A freeze-thaw indicator comprising: a frangible ampul; a porton of the inner surface of said ampul being irregular for promoting crystal growth; a material in said frangible ampul adapted to undergo a phase change at a predetermined temperature, said material undergoing volumetric expansion as it passes below said predetermined temperature in going to a solid phase rupturing said ampul; a nucleating agent contained by said ampul for further promoting crystal growth; a blister pack including a top portion and a bottom portion, said top portion of said blister pack including at least one raised portion, said frangible ampul being contained by said blister pack; said raised portion protecting said ampul from mechanical shock.

Claim 30

Dependent Claim 113 words

A freeze-thaw indicator comprising: a frangible ampul; a porton of the inner surface of said ampul being irregular for promoting crystal growth; a material in said frangible ampul adapted to undergo a phase change at a predetermined temperature, said material undergoing volumetric expansion as it passes below said predetermined temperature in going to a solid phase rupturing said ampul; a nucleating agent contained by said ampul for further promoting crystal growth; a blister pack including a top portion and a bottom portion, said top portion of said blister pack including at least one raised portion, said frangible ampul being contained by said blister pack; said raised portion protecting said ampul from mechanical shock.

Claim 31

Dependent Claim 15 words

A device as set forth in claim 27 wherein said blister pack is substantially transparent.

Claim 32

Dependent Claim 19 words

A device as set forth in claim 28 further including a heat conductive backing attached to said blister pack.

Claim 33

Dependent Claim 38 words

A device as set forth in claim 28 further including an ampul, said ampul being substantially filled with water, and an indicator material responsive to said water; said ampul and said indicator being cover by said blister pack.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1982-03-26	1982-09-25	1983-03-27	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1986-03-26	1986-09-25	1987-03-27	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1990-03-26	1990-09-25	1991-03-27	$7700.00	Window Closed / Lapsed

Freeze-thaw indicator

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