Patent ID: 8297107
Filing Date: 2012-10-30
Classification: G01N

Abstract:
1. A system for regulating fluid flowing through a chromatographic column, comprising: a thermal desorption unit that supplies a carrier gas containing analytes to be measured, the thermal desorption unit including a gas chromatograph in fluid communication with said thermal desorption unit, said gas chromatograph comprising a transfer line assembly through which the carrier gas is communicated from the thermal desorption unit to said column; a signal cable by which said temperature sensor is connected to said thermal desorption unit, the signal cable being bound into the transfer line assembly; and a rotary valve, wherein the removable sample vessel, trap and transfer line assembly are selectively in communication with each other via the rotary valve, wherein said thermal desorption unit controls the pressure of the carrier gas supplied to said column based on the signal received from said sensor, wherein said thermal desorption unit adjusts the pressure of the carrier gas supplied to said column such that a substantially constant flow rate and a substantially constant velocity is maintained in said column, and wherein the pressure of the carrier gas supplied to the column is calculated in accordance with the equation where T t is the transfer line absolute temperature, T c is the column absolute temperature, T a is the standard ambient absolute temperature, P o is the gas pressure at the column outlet, P a is the standard ambient pressure, and a and b represent πd/256Lη for the transfer line and the column, respectively, where d is the diameter thereof, L is the length thereof, and η is the viscosity of the gas flowing therethrough.