Liebig condenser

This is the common laboratory heat exchanger. Cold water flows through the outer jacket in order to cool and condense vapours in the centre tube. It is commonly used in reflux and distillation apparatus.

Water always enters at the bottom of the condenser and leaves at the top. If this is not done air bubbles may form, and the cooling is less efficient. Only a slow flow of cold water is required. Students often have far too fast a flow rate. This has little effect on the cooling power. However, it is very likely that your tubing will fly off the condenser in the middle of the experiment, and a small flood will result. Not a good result for a practical assessment and potentially hazardous!

Click on the picture for a larger image.

Video - correct flow direction through a Liebig condenser