Open to interpretation; “to facilitate the motion of liquids”, the commentary invites this as to forestall the accumulation of liquids; indicates an impervious surface area although not essentially nonabsorbent. My two cents is in which the duct is uncovered it is needed to be 26 gauge. If it is covered https://garage-attic-lift87642.theobloggers.com/41069569/the-5-second-trick-for-lifts