Liebig, Graham or Allihn? Choosing the right condenser geometry
Buying Guide · 5 min read · Vitreon technical desk
Three classic geometries, three different jobs. Matching condenser to boiling point and orientation is a five-minute decision that prevents lost solvent and flooded benches.
01Liebig: distillation default
The straight-jacket Liebig has modest surface area but an unobstructed bore — condensate drains cleanly at any angle, making it the standard for downward distillation. For solvents boiling above ~80 °C, a 250–400 mm Liebig is all you need.
02Graham: cold-trap performance, vertical only
The coiled inner path multiplies surface area, catching low boilers (ether, DCM, pentane) a Liebig lets through. But the coil traps liquid in horizontal use — Graham condensers belong upright, as reflux or receiving condensers, never on a distillation arm.
03Allihn: reflux workhorse
Bulbs give area without trapping condensate in vertical orientation — the classic reflux and Soxhlet condenser. Condensate rains reliably back into the flask, and the bulbs slow vapour enough to stop flooding at vigorous boil.
04Sizing rule of thumb
Jacket length ≥ 10 mm per °C below 100 of the solvent's boiling point, then round up. Distilling DCM (40 °C)? That is 600 mm of Liebig — or a 300 mm Graham doing the same job in half the height.