Patents by Inventor Douglas C. Stewart

Douglas C. Stewart 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).

  • Igniter assembly
    Patent number: 7264775
    Abstract: An igniter assembly for a pulsed flame photometric detector having a filament comprising a resistive heating wire between about 0.08 millimeter and about 0.40 millimeter in diameter wound into a coil having an inner diameter between about 0.40 millimeter and about 3.2 millimeters. The filament has an applied protective coating of an alloy of gold and palladium. The filament is detachably connected to a cable and connector assembly that connects the filament to a source of power in the pulsed flame photometric detector.
    Type: Grant
    Filed: January 20, 2003
    Date of Patent: September 4, 2007
    Assignee: Midwest Research Institute, Inc.
    Inventors: Keith D. Wilson, Stephen B. Cummins, Douglas C. Stewart
  • Self-tuning pulse flame photometric detector system and associated method of self-tuning
    Patent number: 6922238
    Abstract: A system and method for tuning a pulsed-flame photometric detector including providing a carrier gas within a predetermined gas flow range to the pulsed-flame photometric detector, providing at least one combustible fuel to the pulsed-flame photometric detector, applying voltage to an igniter coil associated with the pulsed-flame photometric detector, verifying that the pulsed-flame photometric detector is pulsing above a lower predetermined frequency and above a higher predetermined frequency, adjusting the gas flow of the at least one combustible fuel to the pulsed-flame photometric detector so that at least one cycle of ignition, propagation and then termination is present, heating a container to a predetermined temperature, allowing the at least one carrier gas to flow within the container, housing a tuning compound, and monitoring a width of a sulfur emission resulting from the combustion of the tuning compound to evaluate the width of sulfur emission signal all through a controller.
    Type: Grant
    Filed: January 23, 2003
    Date of Patent: July 26, 2005
    Assignee: Midwest Research Institute, Inc.
    Inventors: Plamen G. Doynov, Douglas C. Stewart, Keith D. Wilson
  • Low-power gas chromatograph
    Patent number: 6837096
    Abstract: A low-power gas chromatograph is provided including an optional air sampler module, an injector, an analytical column, a pulsed-flame photometric detector, and a computer system. The gas chromatograph of the present invention is designed for portable use such that the sensitive components of the system are mounted in a way that they are at least partially insulated against shock applied to the instrument. A rugged housing is provided such that the instrument can be used during field operations without destruction of sensitive components due to dropping and the like.
    Type: Grant
    Filed: January 23, 2003
    Date of Patent: January 4, 2005
    Assignee: Midwest Research Institute, Inc.
    Inventor: Douglas C. Stewart
  • LOW-POWER GAS CHROMATOGRAPH
    Publication number: 20040144159
    Abstract: A low-power gas chromatograph is provided including an optional air sampler module, an injector, an analytical column, a pulsed-flame photometric detector, and a computer system. The gas chromatograph of the present invention is designed for portable use such that the sensitive components of the system are mounted in a way that they are at least partially insulated against shock applied to the instrument. A rugged housing is provided such that the instrument can be used during field operations without destruction of sensitive components due to dropping and the like.
    Type: Application
    Filed: January 23, 2003
    Publication date: July 29, 2004
    Applicant: MIDWEST RESEARCH INSTITUTE, INC.
    Inventor: Douglas C. Stewart
  • SELF-TUNING PULSE FLAME PHOTOMETRIC DETECTOR SYSTEM AND ASSOCIATED METHOD OF SELF-TUNING
    Publication number: 20040145736
    Abstract: A system and method for tuning a pulsed-flame photometric detector including providing a carrier gas within a predetermined gas flow range to the pulsed-flame photometric detector, providing at least one combustible fuel to the pulsed-flame photometric detector, applying voltage to an igniter coil associated with the pulsed-flame photometric detector, verifying that the pulsed-flame photometric detector is pulsing above a lower predetermined frequency and above a higher predetermined frequency, adjusting the gas flow of the at least one combustible fuel to the pulsed-flame photometric detector so that at least one cycle of ignition, propagation and then termination is present, heating a container to a predetermined temperature, allowing the at least one carrier gas to flow within the container, housing a tuning compound, and monitoring a width of a sulfur emission resulting from the combustion of the tuning compound to evaluate the width of sulfur emission signal all through a controller.
    Type: Application
    Filed: January 23, 2003
    Publication date: July 29, 2004
    Applicant: MIDWEST RESEARCH INSTITUTE, INC.
    Inventors: Plamen G. Doynov, Douglas C. Stewart, Keith D. Wilson
  • IGNITER ASSEMBLY
    Publication number: 20040139876
    Abstract: An igniter assembly for a pulsed flame photometric detector having a filament comprising a resistive heating wire between about 0.08 millimeter and about 0.40 millimeter in diameter wound into a coil having an inner diameter between about 0.40 millimeter and about 3.2 millimeters. The filament has an applied protective coating of an alloy of gold and palladium. The filament is detachably connected to a cable and connector assembly that connects the filament to a source of power in the pulsed flame photometric detector.
    Type: Application
    Filed: January 20, 2003
    Publication date: July 22, 2004
    Applicant: MIDWEST RESEARCH INSTITUTE, INC.
    Inventors: Keith D. Wilson, Stephen B. Cummins, Douglas C. Stewart