A medical injection system (100, 200) comprising a pump having an inlet port (26-F) and an outlet port; a first tubing line including a first end coupled to the outlet port of the pump and a second end adapted for connection to a patient line for injection of fluid from the pump; a second tubing line (27-F) including a first end coupled to the inlet port (26-F) of the pump and a second end adapted for connection to a fluid reservoir for filling the pump with the fluid; and a valve apparatus for controlling flow into and out from the pump, the valve apparatus comprising: a rotatable shaft; a pinching member coupled to the rotatable shaft such that the pinching member moves around a central axis of the shaft when the shaft is rotated; a first anvil attached to a first spring member and located on a first side of the shaft; and a second anvil attached to a second spring member and located on a second side of the shaft, the second side being generally opposite the first side; wherein the first tubing line is positioned between the pinching member and the first anvil of the valve apparatus, and the second tubing line is positioned between the pinching member and the second anvil of the valve apparatus; wherein rotation of the shaft moves the pinching member from a first position to a second position; the pinching member compresses the first tubing line against the first anvil at the first position; and the pinching member compresses the second tubing line against the second anvil at the second position, characterized in that each of the first and second spring members of the valve apparatus comprises an elongate flexure, each flexure having a fixed first end and a floating second end, each second end having the corresponding anvil attached thereto, wherein the valve apparatus further comprises a pair of pre-load supports, each pre-load support being located adjacent a corresponding floating second end of the corresponding flexure for pre-loading thereof and in that the pinching member of the valve apparatus is rotatably mounted about an auxiliary axis that is offset from the central axis of the shaft so that the pinching member rolls into and out of contact with the first tubing line (27-I) and the second tubing line (27-F) when moved between the first and second positions. a rotatable shaft; a pinching member coupled to the rotatable shaft such that the pinching member moves around a central axis of the shaft when the shaft is rotated; a first anvil attached to a first spring member and located on a first side of the shaft; and a second anvil attached to a second spring member and located on a second side of the shaft, the second side being generally opposite the first side; wherein the first tubing line is positioned between the pinching member and the first anvil of the valve apparatus, and the second tubing line is positioned between the pinching member and the second anvil of the valve apparatus; wherein rotation of the shaft moves the pinching member from a first position to a second position; the pinching member compresses the first tubing line against the first anvil at the first position; and the pinching member compresses the second tubing line against the second anvil at the second position,