A clamp for clamping flexible tubing, comprising: a first element having a first surface with a first corner; a second element having a second surface with a second corner; and a flexible element coupled to the first and second elements (72, 74), the flexible element configured such that: when the clamp is not actuated, the first and second surfaces (72A, 74A) are disposed at an angle to each other; when the first element is rotated about the flexible element toward the second element, with the flexible tubing between the first and second elements (72, 74), the first and second corners (72B, 74B) are displaced toward each other and cooperate to sealingly compress a first length of the flexible tubing between the first and second corners (72B, 74B); and characterized in that when the first element is further rotated about the flexible element toward the second element, the first element rotates with respect to the second element such that (i) the first and second corners (72B, 74B) separate from each other, and (ii) the first and second surfaces (72A, 74A) cooperate to sealingly compress a second length of the flexible tubing between the first and second surfaces (72A, 74B). a first element having a first surface with a first corner; a second element having a second surface with a second corner; and a flexible element coupled to the first and second elements (72, 74), the flexible element configured such that: when the clamp is not actuated, the first and second surfaces (72A, 74A) are disposed at an angle to each other; when the first element is rotated about the flexible element toward the second element, with the flexible tubing between the first and second elements (72, 74), the first and second corners (72B, 74B) are displaced toward each other and cooperate to sealingly compress a first length of the flexible tubing between the first and second corners (72B, 74B); and characterized in that when the first element is further rotated about the flexible element toward the second element, the first element rotates with respect to the second element such that (i) the first and second corners (72B, 74B) separate from each other, and (ii) the first and second surfaces (72A, 74A) cooperate to sealingly compress a second length of the flexible tubing between the first and second surfaces (72A, 74B). when the clamp is not actuated, the first and second surfaces (72A, 74A) are disposed at an angle to each other; when the first element is rotated about the flexible element toward the second element, with the flexible tubing between the first and second elements (72, 74), the first and second corners (72B, 74B) are displaced toward each other and cooperate to sealingly compress a first length of the flexible tubing between the first and second corners (72B, 74B); and characterized in that when the first element is further rotated about the flexible element toward the second element, the first element rotates with respect to the second element such that (i) the first and second corners (72B, 74B) separate from each other, and (ii) the first and second surfaces (72A, 74A) cooperate to sealingly compress a second length of the flexible tubing between the first and second surfaces (72A, 74B).