A filtration system comprising a solvent vessel , a plurality of filter stages and the same plurality of transfer tubes , wherein: the solvent vessel has: a thermally insulated side wall ; an inlet port for introducing pressurized gas; and an outlet tube having a first end located at a bottom region of the solvent vessel and a second end located outside the solvent vessel ; and the transfer tubes are each removably connected: at an outlet end thereof to one of the inlet ports in one of the lids of the filter stages ; and at an inlet end thereof to either the second end of the outlet tube of the solvent vessel or the outlet port of another of said filter stages such that the solvent vessel and the filter stages are connected in series, characterized in that each filter stage has: a thermally insulated cylindrical side wall ; a lid that is removable from said wall; a replaceable, elongated filter cartridge ; a support having a cartridge locating surface that positions a base of said filter cartridge centrally in the filter stage ; an inlet port in the lid located to introduce liquid into the filter cartridge ; an inlet port located to introduce pressurized gas into the filter stage outside of the filter cartridge ; and a base with an outlet port that drains fluid from outside the filter cartridge . a thermally insulated side wall ; an inlet port for introducing pressurized gas; and an outlet tube having a first end located at a bottom region of the solvent vessel and a second end located outside the solvent vessel ; and the transfer tubes are each removably connected: at an outlet end thereof to one of the inlet ports in one of the lids of the filter stages ; and at an inlet end thereof to either the second end of the outlet tube of the solvent vessel or the outlet port of another of said filter stages such that the solvent vessel and the filter stages are connected in series, characterized in that each filter stage has: a thermally insulated cylindrical side wall ; a lid that is removable from said wall; a replaceable, elongated filter cartridge ; a support having a cartridge locating surface that positions a base of said filter cartridge centrally in the filter stage ; an inlet port in the lid located to introduce liquid into the filter cartridge ; an inlet port located to introduce pressurized gas into the filter stage outside of the filter cartridge ; and a base with an outlet port that drains fluid from outside the filter cartridge . at an outlet end thereof to one of the inlet ports in one of the lids of the filter stages ; and at an inlet end thereof to either the second end of the outlet tube of the solvent vessel or the outlet port of another of said filter stages such that the solvent vessel and the filter stages are connected in series, characterized in that each filter stage has: a thermally insulated cylindrical side wall ; a lid that is removable from said wall; a replaceable, elongated filter cartridge ; a support having a cartridge locating surface that positions a base of said filter cartridge centrally in the filter stage ; an inlet port in the lid located to introduce liquid into the filter cartridge ; an inlet port located to introduce pressurized gas into the filter stage outside of the filter cartridge ; and a base with an outlet port that drains fluid from outside the filter cartridge . a thermally insulated cylindrical side wall ; a lid that is removable from said wall; a replaceable, elongated filter cartridge ; a support having a cartridge locating surface that positions a base of said filter cartridge centrally in the filter stage ; an inlet port in the lid located to introduce liquid into the filter cartridge ; an inlet port located to introduce pressurized gas into the filter stage outside of the filter cartridge ; and a base with an outlet port that drains fluid from outside the filter cartridge . <EOS>