little fmcsa handbooks give the specs for bleed down time etc, you can pick them up at most truckstops. Jar may be for collection of moisture not shore haven't run across it. seems like trucks of the 70's had a place to introduce alchol into air system but I don't remmember now how it went. nowadays with airdryers and proper and regler bleed off not much of a problem. Sometimes pour airline antifreeze in trailer gladhands if there's a problem. suggest you install pull type bleeders on air tanks so you can drain moisture from tanks regularly pain in butt laying underneath truck in freezing weather with a flare trying to thaw frozen valves