Container esp. for perishable food - has membrane bowing if internal pressure increases to indicate decay of contents

摘要

The wall or lid of the container has a disc-shaped area formed as a membrane which bows inwardly or outwardly according to the difference between the internal and external pressure levels. An indicating element (8) for the housing of the membrane (6) is mounted on the outside of the container (1,3) so that it can be read from outside. The indicating element is joined closely flat against the outer form of the container. This element (8) can be an expansion measuring strip glued to the membrane from the outside. At least one transparent display foil is tensioned flat over the membrane. ADVANTAGE - Obvious signal given that quality of contents is not up to standard.