Infusion pump system and associated methods The invention provides a fluid delivery system (1), comprising: an outlet tube (6)； a pump (2) for pumping liquid along a fluid path (100) including the outlet tube； a closed sensing tube (104) branched from the fluid path which, in use, is filled with gas； and a sensor (108) configured to sense movement of a liquid front within the sensing tube and, responsive to sensing of said movement, determine that a partial or total occlusion has occurred within the outlet tube.
