Extractors acc. to Knöfler-Böhm, DURAN® tubing The condensate passes the extraction sample and flows back into the flask continuously without interrupting the extraction process, i.e. the solvent is recirculated continuously. The complete apparatus consists of: Jacketed extractor head made of DURAN® tubing, Dimroth condenser with thread GL 14, made of DURAN® tubing, Round bottom flask material: DURAN®