Dave, Why doesn't the charcoal get saturated? on my application my best guess is the loop in the line before the cannister, I think it probably prevents the fumes from just pouring out and still allowing expansion and suction to occur, Like I mentioned I have done it on at least 6 vehicles and never a hint of fumes in the garage, yes Deans the one selling the cannister for a kings ransom, my where turned and polished out of thick wall polished aluminum with 1/4 plate aluminum ends that could be tapped for fittings, it has served me well and looks nice but I kept them visible from the underside. From what I found out activated charcoal is activated charcoal wether its for a few bucks in the aquarium section or used in medical supplies costing way more. I also put a small wire screen on the intake even though the nylon stocking kept it enclosed just incase os some unforseen failure.