Fluid delivery mechanism having a flush-back operation

A method for infusing a liquid from a source of the liquid through a tube comprising:

• providing a tube for delivery of a liquid from a source of liquid;
• drawing liquid from the source of liquid into a metering chamber in the tube;
• occluding the tube at an upstream position of the metering chamber;
• and
• compressing the tube to push a portion of the liquid in the metering chamber of the tube in a direction towards the source of the liquid and through the occluded section of the tube;
• such that the tube is re-opened using the liquid pushed towards the source of the liquid and through the pinched-off section of the tube, thereby improving the accuracy of the flow of the liquid.

A device for re-opening a tube connected to a source of a liquid, the device comprising:

• means for drawing liquid from a source of liquid into a metering chamber in a tube;
• means for releasably pinching off a section of the tube;
• a first means for pushing a first portion of the liquid in the metering chamber of the tube in a flow direction;
• and
• a second means for directing a second portion of the liquid in the metering chamber through the pinched-off section of the tube towards the source of the liquid;
• such that the flow of the second portion of liquid re-opens the tube thereby improving the accuracy of the flow of the liquid.

A method of metering fluid in a tube comprising:

• drawing liquid from a source of liquid into a tube;
• closing the tube in a first location;
• downstream of the first location, compressing the tube to a first non-occluded position;
• downstream of the tube compression, closing the tube in a second location to define a metering chamber in the tube between the first location and the second location;
• releasing the tube in a first location;
• decompressing the tube to a second non-relaxed position to cause a portion of the liquid drawn from the source of liquid to flow through the tube past the first location toward the source of liquid.

A method for re-opening a tube connected to a source of liquid following a delivery cycle comprising the steps of:

• providing a source of liquid for delivery;
• drawing liquid from said source of liquid into a metering chamber in a flexible tube, said metering chamber defined by a downstream occluder in a closed position at a first end and an upstream occluder at a second end wherein said second end is closer to said source of liquid than said first end;
• closing said upstream occluder after said drawing liquid from said source of liquid;
• opening said downstream occluder and forcing a first portion of said drawn liquid in said metering chamber past said downstream occluder;
• and,
• opening said upstream occluder and forcing a second portion of said drawn liquid in said metering chamber past said upstream occluder toward the source of liquid.