Basic components of a supercritical fluid extractor

All SF extractors, whatever their complexity and cost, share the same essential components, which are schematically depicted in Fig. 7.2 and described below. 

This unit consists of a steel, aluminium or stainless steel cylinder (preferably furnished with a dip tube), a pressurized head space and a device allowing cooling for long enough to ensure equilibration. 

The interface between the cylinder and the propulsion system consists of a connecting line, which should be as short as possible, furnished with a series of safety devices including a bleed valve — which is especially useful to avoid the unwanted presence of gas in the pump when the connecting line is not short enough a safety valve to avoid pressures above those the system and material used can reasonably withstand a check valve to minimize contamination of the fluid stored in the cylinder and filters of small pore size to remove any contaminant particles from the fluid. 

The extractor cell or thimble, which should be accommodated in an appropriate chamber, must meet a series of requirements, namely  

It should enable ready, convenient insertion of the sample  

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