Pipettes

摘要

A fixed stroke pipette having a measuring piston that controls the volume of liquid aspirated into the pipette reservoir and a larger piston that assures the expulsion of all the aspirated liquid during a discharge stroke. An improved piston arrangement provides a fixed seal for the air chamber in which the measuring piston moves and a separate air passageway to that air chamber, controlled by a spring biased check valve, through which compressed air is delivered to the pipette reservoir during a discharge stroke.