Freeze indicator
US4191125A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 3, 1978 |
| Grant date | Mar 4, 1980 |
| Priority date | — |
| Expiry date | Jul 3, 1998 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S252/962
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
There is provided a freeze indicator which includes a frangible ampule substantially filled with a mixture of water, a nucleating agent, and a surfactant. Upon reaching the freezing point of water, most of the water will freeze and expand, and fracture the frangible ampule. The nucleating agent has substantially similar molecular space grouping to frozen liquid to overcome the undercooling effect. The surfactant provides an increased surface area of contact between the water and the nucleating agent. The frangible ampule is in contact with a pad which has a water soluable dye printed on one side. When the ampule breaks, it releases some of the water, and the dye is wicked to one side of the pad by the water, showing a color change. In order to fine-tune the freeze indicator, varying amounts of deuterium oxide may be added to the water to raise its freezing point.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.