Temperature indicating device
US5404834A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 15, 1993 |
| Grant date | Apr 11, 1995 |
| Priority date | — |
| Expiry date | Mar 15, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K11/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An indicator device indicates that the temperature in a location in which the device is placed has exceeded a predetermined maximum temperature value. The he device includes a liquid receptacle comprising frangible bulb portion and an integral capillary portion and an absorbent card to which said receptacle is secured. The bulb portion contains a first liquid and the capillary portion contains a second liquid which is insoluble in said first liquid. The second liquid has a freezing point higher then that of the first liquid and close to but greater than the predetermined temperature value so that when the device is placed in a location which has temperature lower than the predetermined value and in which the predetermined value is to be maintained, the second liquid freezes in the capillary tube and prevents the first liquid from expanding. Thus, if the temperature in the monitored location increases such that expansion of the first liquid causes breakage of the frangible bulb and the release of the first liquid that liquid will cause staining of the absorbent card to provide an indication that the predetermined value has been exceeded within the location.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.