GB1030178A - Pipette - Google Patents

Abstract

A pipette (see Division B1) is formed out of a single glass tube as illustrated in Figs. 5-7 (not shown), by assembling a pair of shell sections 18, 20 and a ring 22 on a hollow mandrel having capillary section 161 and a larger bore portion 1611, shrinking a wide bore glass tube 14 on to the assembly by applying heat and reduced pressure whilst cooling the mandrel and finally withdrawing the mandrel and dissolving the shell and ring. As the glass is softened adjacent the shell sections and ring a sudden vacuum of short duration is applied causing the blank to shrink in sharp conformity with the shell sections and ring. Reference has been directed by the Comptroller to Specification 866,519.ALSO:A pipette suitable for the accurate dilution of blood samples comprises, in the end wall of the bulb 6 (Fig. 2, not shown) adjacent to the liquid withdrawal tube 5 of capillary dimension, a cylindrical well 9. The glass forming the wall of the well 9 and of the adjacent capillary tube and bulb are substantially free from internal stresses and optical distortion. The pipette is formed out of a single glass tube, e.g. as illustrated in Figs. 5-7 (not shown), by assembling a pair of shell sections 18, 20 and a ring 22 on a hollow mandrel having capillary section 161 and larger bore portion 1611, shrinking a wide bore glass tube 14 on to the assembly by applying heat and reduced pressure and finally withdrawing the mandrel and dissolving the shell and ring. A glass mixing bead 10 may be included in the shell before shrinking. In use, the capillary tube is placed in the blood sample, which rises therein to the clearly defined and easily visible level of the bottom of the well, and diluent is then aspirated into the pipette to mix with the blood and rise to a marked level 12. Reference has been directed by the Comptroller to Specification 866,519.