Device for visually indicating a pressure or temperature condition
US4793717A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 6, 1982 |
| Grant date | Dec 27, 1988 |
| Priority date | — |
| Expiry date | May 6, 2002 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01K11/06
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Indicating device suitable for visibly indicating conditions such as the application of force or pressure or the exposure to a critical temperature. The device includes a porous pad containing an indicating dyed chemical, a wick maintained in spaced relation to the pad and a snap action activating means. The activating means forces the wick into contact with the pad and dyed chemical migration provides visible indication of the application of force or pressure. The indicating dyed chemical may be frozen and the activating means engaged. Upon reaching a critical temperature the frozen chemical melts allowing dye migration into the wick and a visible indication of exposure to the critical temperature.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.