Patents by Inventor Donald Holdt

Donald Holdt 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).

  • Boiler blow down controller
    Patent number: 4070992
    Abstract: A combined timer, blow down warning device, chemical pump, and controller for boilers. The circuit comprises an electro-mechanical array of relays, flashing lights and alarms and an electronic tripper which operates from the rate of change in temperature in the blow down tailpipe, to turn off the lights and alarms only after a manual blow down operation has been performed.
    Type: Grant
    Filed: April 23, 1976
    Date of Patent: January 31, 1978
    Assignee: Chemed Corporation
    Inventor: Donald Holdt