Dave, An acetylene tank must never be used while it is lying on its
side. Pressurized acetylene is unstable on its own, so it is
dissolved under pressure in acetone. When you use acetylene from your
tank, it is actually coming out of solution as a gas somewhat like
Carbon dioxide bubbles out of soda pop. If you set the tank on its
side you will get liquid acetone flowing into your torch.
Oxygen is a gas at storage pressure (2200 psig). It is probably
safe to use lying on its side, but I will defer to other Orchidians
who may have some more knowledge oxygen.
Hope this is helpful
Calgary Alberta Canada