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US 5,634,961 AGranted
Gas chromatography system with thermally agile oven
AssigneeHewlett-Packard Company
InventorGary B. Gordon
Life of this patent
Estimating the term…
Abstract
A high-performance, field-portable, thermally agile, gas chromatography (GC) system employs a low-thermal-mass oven in which intake and exhaust vent apertures are aligned with respect to the rotational axis of the stirring fan. The poppets of the vent dynamically vent to ambient the air-flow generated by the stirring fan. The geometry of the vents cooperates with the axial and radial components of the stirring fan to promote conical vortex air flow, to facilitate rapid and controllable mass-flow interchange with ambient air. The resulting cooling performance in a small GC oven promotes more rapid requilibration between runs, control at temperatures closer to ambient, and the reduction of thermal overshoot; thus enhancing the performance and productivity of a field instrument.
Claims15
A method for controlling the temperature of a gas chromatography column in an oven having an intake vent and an exhaust vent, comprising:
- generating heat in a heater in the oven to heat the oven and the column;
- controlling the temperature the column, when the exhaust vent and the intake vent are closed, by blowing with a fan axially aligned with the intake vent and the exhaust vent to cause air to pass over the column and the heater;
- and
- cooling the column by opening the intake vent on an intake side of the oven to admit intake air into the oven and opening the exhaust vent on an exhaust side of the oven opposite to the intake side to discharge exhaust air and by blowing air with the fan, wherein the intake vent has an intake aperture and a movable intake poppet and the exhaust vent has an exhaust aperture and a movable exhaust poppet, and wherein opening the intake vent includes moving the intake poppet initially axially along an axis extending between said apertures to allow the intake air to enter said intake aperture, and opening the exhaust vent includes moving the exhaust poppet initially axially along said axis to allow air to exit the exhaust aperture.
1 more element
A gas chromatography system comprising:
- a gas chromatography column;
- a sample source for introducing sample components into said column, said sample source being in fluid communication said column;
- a detector for detecting sample components exiting said column, said detector being optically coupled with said column;
- a chamber enclosure defining an oven cavity enclosing said column;
- an adjustable heater located within said oven cavity;
- a ventilation subsystem including
- an intake vent having an intake aperture and a movable intake poppet on an intake side of the chamber enclosure, said intake poppet having an open position causing the intake vent to be in an open condition, said intake poppet also having a closed position causing said intake vent to be in a closed condition, said input vent while in its open condition admitting air into said cavity, said input vent while in its closed condition preventing air from entering said cavity through said intake aperture, and
- an exhaust vent having an exhaust aperture and a movable exhaust poppet on an exhaust side of the chamber enclosure opposite the intake side, said exhaust poppet having an open position causing the exhaust vent to be in on open condition said exhaust poppet also having a closed position causing said exhaust vent to be in a closed condition, said exhaust vent while in its open condition allowing air to exit said oven cavity, said exhaust vent while in its closed condition preventing air from exiting said cavity through said exhaust aperture;
- fan means for stirring air within said oven cavity while said intake vent and said exhaust vent are in their respective closed conditions and further for forcing air into said cavity through said intake aperture and forcing air out said exhaust aperture while said input vent and said output vent are in their respective open conditions, said fan means including a rotating element located between said intake vent and said exhaust vent, said rotational element rotating about an axis that extends through said intake aperture and said exhaust aperture;
- and
- temperature control means for implementing a temperature ramp of said column, said control means being coupled to said heater for controlling it, said control means being coupled to said ventilation system for opening and closing said intake vent and said exhaust vent.
8 more elements
A gas chromatography system comprising:
- a chamber enclosure defining an oven cavity;
- a ventilation subsystem including
- an intake vent on an intake side of the chamber enclosure, said intake vent having an intake aperture and a movable intake poppet to open and close said intake aperture for open and closed conditions, said input vent while in its open condition admitting air into said cavity around the perimeter of the intake poppet, said input vent while in its closed condition preventing air from entering said cavity through said intake aperture, and
- an exhaust vent on an exhaust side of the chamber enclosure opposite the intake side, said exhaust vent having an exhaust aperture larger than the intake aperture and a movable exhaust poppet to open and close said exhaust aperture for open and closed conditions, said exhaust vent while in its open condition allowing air to exit said oven cavity around the perimeter of the exhaust poppet, said exhaust vent while in its closed condition preventing air from exiting said cavity though said exhaust aperture;
- fan for stirring air within said oven cavity while said intake vent and said exhaust vent are in their respective closed conditions and further for forcing air into said cavity through said intake aperture and forcing air out of said cavity through said exhaust aperture while said input vent and said output vent are in their respective open conditions, said fan including a rotational shaft located between said intake vent and said exhaust vent, said rotational shaft being rotatable about an axis that extends through said intake aperture and said exhaust aperture;
- an adjustable heater located within said oven cavity;
- a gas chromatography column located within said oven cavity;
- a sample source for introducing sample components into said column, said sample source being in fluid communication said column;
- a detector for detecting sample components exiting said column, said detector being optically coupled with said column;
- and
- temperature control means for implementing a temperature ramp of said column, said control means being coupled to said heater for controlling it, said control means being coupled to said ventilation system for opening and closing said intake vent and said exhaust vent;
- wherein the intake vent, fan, heater, column, and exhaust vent are arranged such that during cooling, air is driven to travel from the intake vent to pass over the heater and the column to the exhaust side of the oven about symmetrical around said axis in a conical fashion.
9 more elements
Dependencies are inferred from the claim text.