Ageing indicator
US4404922A · kind A · utility
7Cited by
17References
17Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 28, 1980 |
| Grant date | Sep 20, 1983 |
| Priority date | — |
| Expiry date | Jul 28, 2000 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S428/913
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An ageing indicator compares a closed sachet of one or more closed tubes of a material which is slightly permeable to a fluid contained in the sachet or tube. The rate of permeation of the fluid through the sachet-like assembly tube wall depends upon temperature and time of exposure to that temperature so the quantity of fluid loss is indicative of temperature and time; the ageing capable of then being detected either by measuring a column of the liquid in a tube or by observing the appearance or disappearance of printed indicia in the sachet.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.