The pipes aren't meant to be full as in sloshing, they're only filled with a few drops. Sometimes it's water, sometimes it's a compressed gas under vacuum. If it's a compressed gas under vacuum, as soon as the pipe is opened - poof, it's gone. If it's water it's usually only damp, enough to create a wicking effect with what are usually sintered copper pipes. Nothing more than a rough surface along the interior pipe walls. Again it's usually under vacuum to reduce boiling point of the fluid, if it were standard water it would have to reach 212f/100c in order to function which isn't the case. It 'boils' at a much lower temp to create the effect inside the pipes and has nothing to do with orientation. The vapor inside the pipes will be...