BLC is the industry leader for cleaning draft systems.

It's a concentrate, so you only need to use 2 oz per gallon of water for routine cleaning.
15 minutes of contact time (longer if you don't clean your lines very often, you know who you are) and rinse completely with clean water.
Great for beer line, faucets, valves etc.
If you are also wanting to prevent/remove beer stone (calcium oxylate) you can follow up the BLC with an ALC treatment.

Contains: Potassium Hydroxide
Caution: May discolor wood, stone or painted finishes.
Make sure all parts are rinsed well, product not safe to ingest.