Patents by Inventor Leif A. Fermvik

Leif A. Fermvik has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 4302917
    Abstract: A fire-seal for a cable penetration is provided with a pre-fabricated fire-sealing body comprising a corrugated tubular casing filled with a pre-compressed fire resisting elastic silicon foam. The body is placed in a site-poured concrete wall before pouring, or in an aerated concrete block from which a fire wall is then built. A tubular tool with a removable tip is driven through the foam so that one or more conduits can be threaded through the tool and foam. The tool is thereafter withdrawn from the foam and opened along an axial slit so that it can be removed transverse to the conduit.
    Type: Grant
    Filed: September 11, 1979
    Date of Patent: December 1, 1981
    Assignee: Telefonaktiebolaget L M Ericsson
    Inventors: Leif A. Fermvik, Bo E. Ohlsson, Aage E. Skinstad