PIPETTE

摘要

A pipette is provided with a cylinder (1) having a front end (1a) to which a pipette tip (3) is removably attached, and also with a piston (7) fitted in the cylinder chamber (6) so that the piston (7) can be advanced and retracted, and the pipette sucks liquid when the piston (7) is retracted and discharges the sucked liquid when the piston (7) is advanced. A communication groove (17) is provided in the outer periphery of the piston (7). The communication groove (17) is located outside the cylinder chamber (6) when the piston (7) is located at the retracted position, and the communication groove (17) causes the inside and outside of the cylinder chamber (6) to communicate with each other when the amount of advance of the piston (7) is greater than a predetermined dimension. When the amount of advance of the piston (7) is greater than the predetermined dimension, the sealing between the cylinder chamber (6) and the piston (7) is rendered ineffective. This causes the pressure within the cylinder chamber (6) to be the same as the atmospheric pressure, thereby cancelling the suction/discharge effect.