Subclass 5/08: Jet pumps, i.e. devices in which fluid flow is induced by pressure drop caused by velocity of another fluid flow (diffusion pumps F04F 9/00; combination of jet pumps with pumps of other than jet type F04B; use of jet pumps for priming or boosting non-positive-displacement pumps F04D) the inducing fluid being liquid displacing elastic fluids the elastic fluid being entrained in a free-falling column of liquid