A flow sensor sub-assembly for sensing flow of a fluidic medicament comprisinga flow tubeassembly having: a flow tube having a lumen, an outside diameter, a first end,and a second end,an inlet fitting sized for insertion of either end of said flow tube, and anoutlet fitting sized forinsertion of either end of said flow tube. The sub-assembly also comprises afirst transducer atthe inlet fitting upstream of the flow tube assembly and a second transducerat the outlet fittingdownstream of the flow tube assembly, such that the first transducer is spacedfrom one of thefirst end and the second end of the flow tube in a direction upstream thereofand the secondtransducer is spaced from the other of the first end and the second end of theflow tube in adirection downstream thereof.
