The Variable Pressure Sampler (VPS) works in two ways to ensure the precision and accuracy of gas results. The first method is pressure correction, used to create uniform pressure among all injected samples and the calibration blend. The second method is multi-point calibration, which can deliver a calibration blend to the GC at various pressures.
The VPS pressure correction system performs a multi-step process that ensures samples and calibration blends are at uniform pressures when they are injected.
First, when the calibration blend is run through the GC, the VPS measures and stores the pressure of the calibration blend at the time of injection. Then, as each sample is injected at the stored pressure, the VPS adjusts the pressure of the sample to match the pressure of the calibration blend.
The inject pressure of the sample is reported to Agilent Technologies OpenLAB ChemStation software so calculations and quality control operations can be performed.
Using the VPS, calibration samples can be run at various pressures from a single standard. This decreases overall lab costs while ensuring greater accuracy in results. The multi-point calibration function allows testing for signal linearity at different pressures. With this feature, the user can easily pinpoint the range of pressures which generates the most accurate and meaningful results from the calibration standard.
Wassson: Variable Pressure Sampler (VPS) - linearity
