Plain column with a row of indentations to support column packing.

With indentations to support column packaging.

Plain column, but with a jacket.

Distilling column with floating ball valves for improved vapor-liquid contact. Inner joint at bottom.

Distilling column with floating ball valves for improved vapor-liquid contact. Inner joint at bottom and an outer joint at top of column.

With indentations over the entire length for excellent vapor-liquid contact.