A fluid path for delivery of a fluid comprises first and second flexible tubes, each tube defining a transverse formation extending generally perpendicular to its longitudinal axis. Used to maintain the transverse formation in each tube, a clip mechanism includes a body comprising opposing flanges, each opposing flange defining at least a pair of recesses, each of the pair of recesses receiving one of the first and second flexible tubes, respectively, to define the respective transverse formations. The clip mechanism includes a support section connecting the opposing flanges such that the clip mechanism extends across the transverse formations and maintains their configuration. Due to the transverse formations, fluid contained within either tube at one end portion thereof cannot flow through the length thereof to displace a less dense fluid contained therein at the other end portion thereof under gravitational flow.