I need to transfer 50 gallons from a 55 gallon plastic drum into an
oak barrel (actually from several drums into several barrels.)
Gravity racking is a possibility but I'm thinking I could

a. start the siphon easily, and
b. speed up the transfer

by applying a small amount of vacuum to the barrels. Has anyone
already thought of a simple way to do this? My main concern, of
course, is not imploding the barrel with excessive vacuum. But surely
there's some cheap and reasonable way to regulate things? Anyone know
how much vacuum a barrel can take?