Patents by Inventor Trevor Hallett

Trevor Hallett 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).

  • Pipe freezing apparatus
    Patent number: 5987906
    Abstract: A pipe freezing apparatus 2 has pipe freezer heads 12a, 12b supplied with refrigerant by a compressor 4. The freezer heads 12a, 12b comprise expansion chambers in which the refrigerant expands, to cool the heads. A valve 10 alternately diverts flow of the refrigerant to the freezer heads 12a, 12b. When a supply to a head 12a, 12b is shut off, the compressor lowers the pressure in the head, resulting in enhanced cooling when supply to the head is restored. The compressor 4 can be run continuously while the cooling at the heads is controlled.
    Type: Grant
    Filed: May 14, 1997
    Date of Patent: November 23, 1999
    Assignee: Freeze Master Limited
    Inventor: Trevor Hallett