Medical fluid pump powered by a constant source of vacuum

A vacuum powered pump comprising:

• a) a fluid chamber having an inlet and an outlet;
• b) a first displacement means movable in said fluid chamber from a first position to a second position for creating negative pressure in said fluid chamber and movable from said second position to said first position for creating positive pressure in said fluid chamber;
• c) biasing means for biasing said first displacement means toward said first position;
• d) a vacuum chamber having a vacuum port for coupling with a source of vacuum to provide negative pressure in said vacuum chamber, said first displacement means being responsive to negative pressure in said vacuum chamber such that negative pressure in said vacuum chamber causes said displacement means to move from said first position to said second position;
• and
• e) a delayed action valve fluidly coupled to said vacuum chamber and mechanically coupled to said first displacement means for allowing ambient air to enter said vacuum chamber when said first displacement means is in said second position and to remain open until said displacement means returns to said first position, wherein
• said delayed action valve comprises a cylinder having an air inlet port and a displaceable member within said cylinder, said displaceable member having at least one sealing ring separating said air inlet port from said vacuum chamber when said displacement means is in said first position.