Temperature indicator for refrigerated products or the like

US6030118A · kind A · utility

Assignee

• Emtec Magnetics GmbH · DE

Inventors

• Norbert Schneider · Schorndorf, DE
• Gunther Bettinger · Schifferstadt, DE
• Ronald J. Veitch · Frankenthal (Pfalz), DE

Key dates

• Filing date: Dec 17, 1997
• Grant date: Feb 29, 2000
• Expiry date: Dec 17, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01K11/06
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An apparatus for irreversibly indicating that the permissible temperature of stored products has been temporarily exceeded is described, in which a container has a heat-conducting connection to the product to be monitored and contains, in its interior, a medium having a melting point which is just above the permissible storage temperature, magnetizable particles being suspended in the medium. Moreover, solid magnetizable bodies are uniformly distributed in the container. After the deep-freezing process is complete, the magnetizable particles and the solid bodies are magnetized. If the permissible storage temperature is exceeded, the suspension becomes liquid and the pigments accumulate on the solid bodies, an optical indicator present on a wall of the container and visible from the outside detecting that the permissible temperature has been exceeded.