What is a thump keg used for on a moonshine still

The Thump Keg is a wooden barrel that is in-line between the cooker, and the main condenser. Its use allows one to double the proof of the alcohol while simultaneously cutting the distilling time in half.

It helps draw off the hot water vapor, which in turn helps vaporize the alcohol for a type of second distillation. Before the invention of the Thump Keg, the first output of the still would be run through the system a second time to increase the alcohol content of the moonshine.

If you're wondering why it's called that, it's because when steam is run through the thump keg, it makes a thumping sound; we found one person that described the sound as "POP! POP! Thumpa-thumpa-THUMP! Pop! Pop!"

Note: making moonshine is illegal in the U.S., and if you've been watching Discovery Channel's #1 rated show Moonshiners, it's worth mentioning that all of that show is staged, they are not really making illegally distilled spirits.