an i . v . administration set is provided with a flexible expansion section so as to accommodate an additional volume of liquid without the use of excessive lengths of tubing . the expansion section is in the form of pleated or corrugated tubing which , upon the introduction of liquid into an i . v . set such as by means of a hypodermic syringe , will accommodate an additional portion of liquid which is known in the i . v . administration art as a retrograde volume .