Importance

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Abstract

A pipette with adjustable volume, which pipette comprises a frame portion (1) shaped as a handle, a cylinder (2) being formed inside the said frame portion, as well as a piston (3) fitted into the cylinder by means of a seal ring (7), a piston rod (4) connected to the piston (3), as well as a press knob (5) with shaft (6), fitted at the upper end of the frame portion (1). By turning the said press knob (5), a sleeve (20), which determines the upper position of the piston (3) and which is non-rotable in relation to the frame portion (1) of the pipette, can be displaced, by means of a threaded joint (20), upwards or downwards relative the shaft (6) of the knob so as to adjust the volume of the pipette. The pipettable volume can be read numerically through an opening or window (40) in the pipette frame (1) by means of a series of rings consisting of numbered disc-shaped rings ( 31, 39). According to the invention, above the uppermost ring (31) in the series of rings, a ring-shaped spring (33) is fitted non-rotably in relation to the frame portion (1) of the pipette, the bottom face of the said ring-shaped spring (33) being provided with globular projections (34) designed to be jointly operative with notches provided in the end face of the ring (31), so as to lock the ring (31) gently in the desired volume positions.

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First Claim