Patent ID: 7670480

Claim:
A solvent supply system comprising: a supply flow path; a first metering device with a piston, the first metering device being configured for supplying a first solvent to a mixing unit; a second metering device with a piston, the second metering device being configured for supplying a second solvent to the mixing unit; the mixing unit being configured for mixing the first and the second solvent and for supplying a composite solvent with a mixing ratio of the first and the second solvent into the supply flow path; and a control unit configured for controlling the piston movements of the first and the second metering device to reduce disturbances of the composite solvent's mixing ratio caused by pressure variations in the supply flow path such that the mixing ratio becomes substantially independent of a variation of the solvent pressure of the composite solvent in the supply flow path; wherein the control unit is adapted for compensating for an increase of the solvent pressure by superposing a corresponding forward displacement on the movement of the pistons, and for compensating for a decrease of the solvent pressure by superposing a corresponding backward displacement on the movement of the pistons.