3/16" is the best size for most beer lines under 9' in length. Ideally, 5' provides the correct restriction for serving beer in the 8-14 psi range.
Technical Specifications: 3/16" line provides 2.2 lbs of restriction per foot. Ideally pounds of resistance should equal pounds of applied pressure. 3/16" line holds 1/6 of an ounce per foot. Made from PVC. 5/16" OD