A fluid transfer device comprising: a first member (100; 400; 400'), comprising a first body member (3; 401; 401') having a first valve port, a first door (2; 425; 425'; 931) actuatable between a first valve port open position and a first valve port closed position, and a first valve member (8; 450; 450'); a second member (200; 320; 300'), comprising a second body member (150; 301; 301') having a second valve port, a second door (22; 325; 325') actuatable between a second valve port open position and a second valve port closed position, and a second valve member (110; 350; 350'); said first member (100; 400; 400') and said second member (200; 320; 300') being engageable and lockable to actuate said first door (2; 425; 425'; 931) to said first valve port open position and said second door (22; 325; 325') to said second valve open position, thereby creating fluid communication between said first and second members (100, 200; 400, 320; 400', 300'); characterized in that said first member (100; 400; 400') comprises a first pocket for said first door (2; 425; 425'; 931) when said first door (2; 425; 425'; 931) is in said first valve port open position, and said second member (200; 320; 300') comprises a second pocket for said second door (22; 325; 325') when said second door (22; 325; 325') is in said second valve port open position; said first and second doors (2, 22; 425, 325; 425', 325') are cammed between their open and closed positions; said first member (100; 400; 400') and said second member (200; 320; 300') are engageable and lockable by relative rotation of said first member (100; 400; 400') with respect to said second member (200; 320; 300'), wherein said relative rotation causes said first and second doors (2, 22; 425, 325; 425', 325') to be actuated between their respective open and closed positions; and said relative rotation causes axial displacement of said second valve member (110; 350; 350') into said first member (100; 400; 400'). a first member (100; 400; 400'), comprising a first body member (3; 401; 401') having a first valve port, a first door (2; 425; 425'; 931) actuatable between a first valve port open position and a first valve port closed position, and a first valve member (8; 450; 450'); a second member (200; 320; 300'), comprising a second body member (150; 301; 301') having a second valve port, a second door (22; 325; 325') actuatable between a second valve port open position and a second valve port closed position, and a second valve member (110; 350; 350'); said first member (100; 400; 400') and said second member (200; 320; 300') being engageable and lockable to actuate said first door (2; 425; 425'; 931) to said first valve port open position and said second door (22; 325; 325') to said second valve open position, thereby creating fluid communication between said first and second members (100, 200; 400, 320; 400', 300'); characterized in that said first member (100; 400; 400') comprises a first pocket for said first door (2; 425; 425'; 931) when said first door (2; 425; 425'; 931) is in said first valve port open position, and said second member (200; 320; 300') comprises a second pocket for said second door (22; 325; 325') when said second door (22; 325; 325') is in said second valve port open position; said first and second doors (2, 22; 425, 325; 425', 325') are cammed between their open and closed positions; said first member (100; 400; 400') and said second member (200; 320; 300') are engageable and lockable by relative rotation of said first member (100; 400; 400') with respect to said second member (200; 320; 300'), wherein said relative rotation causes said first and second doors (2, 22; 425, 325; 425', 325') to be actuated between their respective open and closed positions; and said relative rotation causes axial displacement of said second valve member (110; 350; 350') into said first member (100; 400; 400').