Filtration Unit with Flask Filtration Unit with A flask is a common laboratory setup used for separating solids from liquids. This setup typically includes a filter flask, a filtration apparatus, and a vacuum source. This is a specialized flask with an integrated sidearm. The sidearm is used to connect the flask to the filtration apparatus. The filter funnel is attached to the sidearm of the filter flask. Shop online at Labtron.us.