An apparatus for pumping fluid through tubing comprising a stop platen is disclosed. The stop platen is operatively arranged to depress a wall of the tubing along a section of a longitudinal axis of the tubing. The stop platen is narrower than the tubing along a transverse axis of the tubing. The invention further comprises a cabinet containing the stop platen, a door rotatably fixed to the cabinet, and locking means for preventing rotation of the door. The locking means are operatively arranged to be unlocked by a tubing occluder.