Suggest using a propane tank...strong enough for ammonia, shit cheap and not suspicious at all. Open the valve (let out any propane outdoors) and then screw the valve out (it's just threaded, like a big bolt.) Prep your liquid ammonia (suggest condensing it on dry ice) and pour the ammonia in (do NOT completely fill the tank) and make damn sure there's no dry ice left in it before screwing the valve back in. Close valve, you're set. Yes, it'll come out liquid, but there'll be plenty of gas too so be careful. If you closed the valve with some dry ice still in the tank be prepared for something Very Bad to happen.) Industially the liquid NH3 is pumped into the smaller tanks (which themselves are often left open during filling to keep them from pressurizing and slowing the transfer.) Happy cooking, and treat this shit with deep respect--Bob has seen ammonia burn patients come through the ward and it ain't pretty--severe chemical burns over large areas of skin.)
Legion Bob
"We're Everywhere!"