Abstract: A ball-valve for precise and accurate sampling and dispensing is disclosed. The ball-valve includes a body having a through-bore having a first end and a second end lined with a two-part sleeve which partially surrounds a ball. The ball is rotatably mounted within the sleeve and in sealing engagement with the sleeve. The ball includes a blind-bore of a known volume. The ball rotates between a first position, in which the blind-bore registers with the first end, and a second position, in which the blind-bore registers with the second end. Rotation of the ball transports a known volume from communication with the first end to communication with the second end. The sealing engagement between the ball and sleeve will prevent depressurization through the ball-valve of a vessel mounted to the ball-valve, both when the ball is at rest and when rotating. In addition, the sealing engagement between the ball and sleeve ensures only the desired volume of fluid is transported between the first and second positions.