Pumping apparatus for delivering liquid at high pressure

US4883409A · kind A · utility

Inventors

• Fred Strohmeier · Bühl, DE
• Klaus Witt · Keltern, DE

Key dates

• Filing date: Sep 19, 1988
• Grant date: Nov 28, 1989
• Expiry date: Sep 19, 2008

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2030/326
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A pumping apparatus for delivering liquid at a high pressure, in particular for use in liquid chromatography, comprises two pistons (10, 20) which reciprocate in pump chambers (7,18), respectively. The output of the first pump chamber (7) is connected via a valve (13) to the input of the second pump chamber (18). The pistons are driven by linear drives (30,31), e.g., ball-screw spindles. The stroke volume displaced by the piston (10) is freely adjustable by corresponding control of the angle by which the shaft of the drive motor (36) is rotated during a stroke cycle. The control circuitry is operative to reduce the stroke volume when the flow rate which can be selected by user at the user interface (42) is reduced, thus leading to reduced pulsations in the outflow of the pumping apparatus. The pumping apparatus can also be used for generating solvent gradients when a mixing valve (2) connected to different solvent containers (A,B,C,D) is coupled to the input of the pumping apparatus (FIG. 1).