Pipetting device having an automatic mechanism for replacing nozzle tips

A pipetting device is formed of a supporting frame, a slider (13) mounted on the supporting frame (12) for vertical movement, a plunger type stem (16) having a lower end fittable within the upper end of an approximately inverted cone shaped nozzle tip (9), the stem being mounted for vertical movement on the slider, and a conduit (17) for supplied the lower end of the stem with an air supply and exhaust device so that the nozzle tip may be communicated with air or air may be sucked therefrom. A rotating cam (14) cooperates with a pin (13a) on the slider for vertically moving the slider by a large stroke. An air cylinder (18) has a piston fixed relative to the stem for vertically moving the stem by a small stroke. A lever (19) loosely mounted on the lower end of the stem can engage the nozzle tip for removing the nozzle tip from the stem.