Patent ID: 7143636

Claim:
A sealed field device for determining and/or monitoring a physical and/or chemical process variable of a medium in a container, the sealed field device including: at least one housing enclosing a predetermined internal volume; and a first sealing stage connected to said at least one housing and facing away from the medium within the container, wherein: said predetermined internal volume is provided on the side of said first sealing stage facing away from the medium within the container; said at least one housing including at least one opening, which connects the internal volume of said at least one housing with a space outside of the container, said internal volume containing at least one intermediate medium, whose character is such that it indicates via said at least one opening the case in which said first sealing stage no longer seals, and said intermediate medium is of a character such that it indicates at least visually and/or acoustically and/or haptically and/or olfactorially the case in which said first sealing stage no longer seals.