| 摘要 |
While using a metering apparatus which comprises a metering pump (1) including a vertical, elongate pump cylinder (2), and a piston (3) arranged for axial movement in said cylinder, an accurately determined volume of liquid is transferred from a first vessel (6) to a second vessel (7). The pump (1) is lowered into the first vessel (6), so that the pointed part (2a) of the pump cylinder (2) extends down into the liquid contained by the first vessel (6), and the piston (3) is withdrawn through a distance such that a volume of liquid substantially exceeding the volume to be transferred is drawn into the pump cylinder (2), whereafter the pump (1) is raised. The piston (3) is advanced in the cylinder (2) in order to return part of the liquid, whereafter the piston (3) is withdrawn through a short distance, so that any droplet which may have adhered to the pointed part (2a) of the pump cylinder (2) is drawn into the cylinder (2). The pump (1) is then moved to a position above the second vessel (7) and the piston (3) advanced through a distance which corresponds exactly to the volume of liquid to be transferred plus the distance through which the piston (3) was withdrawn in the preceding procedural step. In this way, the desired amount of liquid is dispensed to the second vessel (7). |
