Distillation Flasks with Side Arm

Distillation separates and purifies liquids by boiling them and condensing the vapour, and the distillation flask is where that boiling happens. The angled side-arm is its defining feature: it carries the rising vapour off to a condenser at a controlled point above the liquid, so only what vaporises at the chosen temperature passes through.

Round-bottom and pear shapes heat evenly and withstand the thermal stress of prolonged boiling, and ground-glass joints let the flask connect to condensers, columns and receivers in a standard distillation train.

Simple and fractional distillation, solvent purification and recovery, boiling-point determination, separation of liquid mixtures, and essential-oil distillation, in research, synthesis, teaching and QC labs.

A round-bottom or pear-shaped borosilicate 3.3 body with an angled vapour side-arm, finished with standard-taper ground-glass joints on the neck and arm to connect to thermometers, columns, condensers and receivers. The shape promotes even heating and withstands repeated boiling.

Support a round-bottom flask in a stand or mantle (it cannot stand alone), heat gradually, and add anti-bumping granules to ensure smooth boiling. Ensure condenser cooling water flows before heating, and never heat a closed system — there must be a vent. Assemble with matching greased or clipped joints, and let the flask cool before dismantling.

Blown from borosilicate 3.3 into the round or pear body with the side-arm, fitted with ground-glass joints, then annealed for repeated thermal cycling. Joint sizing (to mate with the train), even wall and thermal performance are the key checks.