I was not planning on mounting the tank with the fittings facing down guys, I realise with minimal thought that air rises, the question was wether the brass fill and tank feed nipples could be on the underside of the main cap (when mounted at 20 degree and facing up) so the air was trapped in the space above the main cap and not sucked into the main fuel feed. There are installations where the UAT is mounted dead vertical, in this position it wont make any difference which way the nipples are facing, so I had to ask if it matters when inclined at 20 degrees.

I could also ask why the UAT can be mounted dead vertical when the instructions say at around 20 degrees?