Agilent Technologies, Inc.

Alexander Bierbaum

Konstantin Choikhet

Klaus E Witt

Hans-Georg Weissgerber

A method for controlling movement of a piston in a metering device is described. The method comprises supplying a fluid by actuating the metering device's piston, wherein compression or expansion of the fluid causes corresponding temperature variations. The method further comprises superposing a corrective movement onto the piston movement, with the corrective movement at least partly compensating for at least one of thermal expansion and contraction of the fluid induced by the temperature variations. In one embodiment, the corrective movement imposed onto the piston movement comprises two components: a reduction () of the compression jump (), and a subsequent increase () of the piston's forward displacement rate () during a period () of time ().

Compensating temperature-induced errors during piston movement

A liquid delivery system having at least one channel, at least one valve within that channel, at least one flow sensing device within that channel, and a pressure source downstream of the valve capable for generating variable pressures.

Leakage checking and calibrating of a liquid delivery system

A supply flow path for supplying a solvent is described. The supply flow path includes metering devices each with a piston, the metering devices being adapted for metering the solvent through separate source paths feeding the supply flow path. The supply flow path further includes a control unit adapted for controlling the metering devices' piston movement in accordance with solvent pressure, wherein a variation of the solvent pressure gives rise to a corresponding variation of a solvent volume contained in the supply flow path or a part thereof. The control unit is adapted for compensating for the variation of the solvent volume by corresponding movements or forward or backward displacements of the pistons.

Solvent supply with correction of piston movement

There is provided a method that includes, (a) monitoring a pressure on a fluid being conveyed through an intake tube into a chamber by a pump, (b) determining a deviation of the pressure from a predefined value, (c) determining a blockage of the intake tube based on the deviation, and (d) determining an amount of an adjustment of a parameter of the pump to compensate for the blockage.

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Karlsruhe, Germany

Alexander Bierbaum