I have a 1 gallon keg... BLC mixed with hot water... Get it to run out of the tap... let it sit for half an hour... Run some more through... sit again... Then hook up a keg with a couple gallons water and flush... D U N..
Of course my lines are under 2'... Something I started doing in the last year...
I looked at the lines and never worried... Well, one day I took one off, used a guitar string and a piece of paper towel, pulled it through... It was right after I barfed, I decided its time...
sneezles61