Methods and systems for characterizing a sorbent tube
View Patent ↗Disclosed are systems and methods that include providing a vessel having an adsorbent disposed therein, the vessel having an inlet and an outlet for communicating a carrier gas through the vessel; determining a differential pressure between the inlet and the outlet for a known flow rate at the outlet; and, determining a geometric measure for the vessel based on a ratio of the known flow rate and the differential pressure. In some embodiments, the methods and systems can include a viscosity in the ratio, determining a flow rate at ambient pressure using a factor based on a ratio of a gas pressure at the output and ambient pressure, and/or, determining a flow rate at ambient temperature using a factor based on a ratio of a temperature at the output and ambient temperature.
1. A chromatographic system, comprising:
a carrier gas inlet for supplying carrier gas;
a chromatographic column for receiving the carrier gas;
a flow path through which the carrier gas is communicated from said carrier gas inlet to said chromatographic column;
a vessel disposed in said flow path, said vessel having an adsorbent disposed therein for adsorbing and desorbing analytes to be measured;
wherein said vessel includes an inlet and an outlet for communicating the carrier gas through said vessel; and
at least one sensor in communication with said flow path, the at least one sensor providing at least one measurement;
wherein the system determines a differential pressure along the adsorbent material based on the at least one measurement and provides a unit flow per unit pressure for the carrier gas in said vessel based on the differential pressure, a flow rate at said vessel outlet, and a viscosity of the carrier gas.
2. The system of claim 1 , where the at least one sensor includes at least one sensor for measuring a pressure at the vessel inlet and a pressure at the vessel outlet.
3. The system of claim 1 , further comprising a heating device for heating the vessel.
4. The system of claim 1 , further comprising a sample container for supplying the analytes to said flow path, wherein said vessel comprises an adsorbent trap for receiving the analytes supplied by said sample container and pre-concentrating the analytes before the analytes are communicated to said chromatographic column.
5. The system of claim 1 , wherein said vessel comprises a sample tube for collecting the analytes before said vessel is disposed in said flow path.
6. The system of claim 5 , further comprising:
a second vessel disposed in said flow path, said second vessel having an adsorbent disposed therein for receiving the analytes supplied by said sample tube and pre-concentrating the analytes before the analytes are communicated to said chromatographic column;
wherein said second vessel includes an inlet and an outlet for communicating the carrier gas through said second vessel; and
at least one additional sensor in communication with said flow path adjacent at least one of the second vessel inlet and the second vessel outlet for determining the impedance of the gas communicated through said second vessel.
7. The system of claim 6 , wherein said at least one additional sensor includes at least one pressure sensing device for measuring the pressure drop across said second vessel.
8. The system of claim 1 , wherein said at least one sensor comprises a differential pressure transducer.
9. The system of claim 1 , wherein said at least one sensor comprises a first pressure transducer that measures a pressure at said vessel inlet and a second pressure transducer that measures a pressure at said vessel outlet.
10. The system of claim 1 , further comprising a vent in communication with said flow path that vents carrier gas exiting said vessel to atmosphere, wherein said at least one sensor comprises a pressure transducer that measures a pressure at said vessel inlet.
11. The system of claim 1 , further comprising a flow controller in said flow path.
12. The system of claim 1 , further comprising a temperature sensor adjacent said vessel.
13. A chromatographic system, comprising:
a carrier gas inlet for supplying carrier gas;
a chromatographic column for receiving the carrier gas;
a flow path through which the carrier gas is communicated from said carrier gas inlet to said chromatographic column;
a vessel disposed in said flow path, said vessel having an adsorbent disposed therein for adsorbing and desorbing analytes to be measured;
wherein said vessel includes an inlet and an outlet for communicating the carrier gas through said vessel; and
at least one sensor in communication with said flow path, the at least one sensor providing at least one measurement that indicates a pressure drop across said vessel.
14. The system of claim 13 , wherein said at least one sensor comprises a differential pressure transducer.
15. The system of claim 13 , wherein said at least one sensor comprises a first pressure transducer that measures a pressure at said vessel inlet and a second pressure transducer that measures a pressure at said vessel outlet.
16. The system of claim 13 , further comprising a vent in communication with said flow path that vents carrier gas exiting said vessel to atmosphere, wherein said at least one sensor comprises a pressure transducer that measures a pressure at said vessel inlet.
17. The system of claim 13 , further comprising a flow controller in said flow path.
18. The system of claim 17 , further comprising a temperature sensor adjacent said vessel.
19. The system of claim 13 , further comprising a heating device for heating said vessel.
20. The system of claim 13 , wherein said vessel comprises a sample tube for collecting the analytes before said vessel is disposed in said flow path, further comprising:
a second vessel disposed in said flow path, said second vessel having an adsorbent disposed therein for receiving the analytes supplied by said sample tube and pre-concentrating the analytes before the analytes are communicated to said chromatographic column;
wherein said second vessel includes an inlet and an outlet for communicating the carrier gas through said second vessel; and
at least one additional sensor in communication with said flow path adjacent at least one of the second vessel inlet and the second vessel outlet that provides a measurement of the gas communicated through said second vessel.