An apparatus comprising: an infusion pump including a pumping mechanism, an actuating member, a follower and a sensor; and an administration set including tubing for conveying an infusion liquid and the free-flow prevention device, the free-flow prevention device operable to selectively stop and permit flow of the infusion liquid through the tubing, wherein the free-flow prevention device comprises: a carrier; a plunger movable relative to the carrier between an open position permitting flow of the infusion liquid through the tubing and a closed position stopping flow of the infusion liquid through the tubing; and means biasing the plunger toward the closed position; wherein the plunger includes a cam surface defining an uneven profile along a direction of movement of the plunger, wherein a shape of the cam surface profile indicates whether the administration set is authorized for use with an infusion pump; and wherein in use, during movement of the plunger, the cam surface is configured to cause displacement of the follower in contact with the cam surface wherein a segment of the tubing is loadable into the infusion pump for engagement by the pumping mechanism; wherein the free-flow prevention device is loadable into the infusion pump and is operated by the actuating member, the actuating member being movable from a non-pumping position to a pumping position thereby moving the plunger from the closed position to the open position; wherein the sensor is arranged to sense movement of the plunger, and the sensor generates a profile signal in the time domain representative of the cam surface profile; and wherein the infusion pump further comprises: a memory storing predetermined reference values; and a processor arranged to receive the profile signal, wherein the processor is programmed to compare the profile signal to the stored reference values and determine whether or not the administration set is loaded in the infusion pump and whether or not the administration set is authorized for use with the infusion pump, based on the comparison. an infusion pump including a pumping mechanism, an actuating member, a follower and a sensor; and an administration set including tubing for conveying an infusion liquid and the free-flow prevention device, the free-flow prevention device operable to selectively stop and permit flow of the infusion liquid through the tubing, wherein the free-flow prevention device comprises: a carrier; a plunger movable relative to the carrier between an open position permitting flow of the infusion liquid through the tubing and a closed position stopping flow of the infusion liquid through the tubing; and means biasing the plunger toward the closed position; wherein the plunger includes a cam surface defining an uneven profile along a direction of movement of the plunger, wherein a shape of the cam surface profile indicates whether the administration set is authorized for use with an infusion pump; and wherein in use, during movement of the plunger, the cam surface is configured to cause displacement of the follower in contact with the cam surface a carrier; a plunger movable relative to the carrier between an open position permitting flow of the infusion liquid through the tubing and a closed position stopping flow of the infusion liquid through the tubing; and means biasing the plunger toward the closed position; wherein the plunger includes a cam surface defining an uneven profile along a direction of movement of the plunger, wherein a shape of the cam surface profile indicates whether the administration set is authorized for use with an infusion pump; and wherein in use, during movement of the plunger, the cam surface is configured to cause displacement of the follower in contact with the cam surface wherein a segment of the tubing is loadable into the infusion pump for engagement by the pumping mechanism; wherein the free-flow prevention device is loadable into the infusion pump and is operated by the actuating member, the actuating member being movable from a non-pumping position to a pumping position thereby moving the plunger from the closed position to the open position; wherein the sensor is arranged to sense movement of the plunger, and the sensor generates a profile signal in the time domain representative of the cam surface profile; and a memory storing predetermined reference values; and a processor arranged to receive the profile signal, wherein the processor is programmed to compare the profile signal to the stored reference values and determine whether or not the administration set is loaded in the infusion pump and whether or not the administration set is authorized for use with the infusion pump, based on the comparison.