Originally Posted by homebrewer_99
It's basically a one-way valve.
It's actually a two way valve since it works both ways. At least the one-piece kind. The three-piece kind will suck in the barrier liquid first.
The only big advantage of airlocks is the ability to see the CO2 escaping and keeping O2 out of the fermenter. Infection could also be prevented by simple tin-foil or attaching a tube that that faces down on the other end. It is not necessary to actually submerge a blow-off tube in water and if it is submerged in water, the water doesn't need to be sanitized. Why? because germs cannot move by themselves and will not crawl from the water into your wort. They need to fall be be blown in.
Currently my primary is sitting in a water bath and the bow-off tube is submerged into this water
. i don't expect anything bad to happen.