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Figure: Operating principle

No.

Description

1

Solvent lines: A and B

2

Flow-controlled pump with two identical pump blocks (solvent channels), A and B

2a

Pump blocks A and B, each pump block with:

2b

Working cylinder

2c

Working pressure sensor

2d

Equilibration cylinder

2e

Primary pressure sensor
The primary pressure is the pressure in the pump head.

3

Flowmeter, as applicable for each channel, with:

3a

Flowmeter inlet line (capillary from pump head)

3b

Flowmeter filter

3c

Automatic purge valve with waste outlet

3d

Flow sensor

3e

Restrictor capillary

3f

System pressure sensor

3g

Flowmeter outlet with fluidic Tee piece (pump outlet)

3h

Waste outlet

4

Capillary to system

The pump is a binary pump with a flowmeter for flow control:

  • Each pump block has a working cylinder and an equilibration cylinder. The cylinders are connected in series. The solvent passes the cylinders successively.

  • Each pump block delivers flow continuously.
    The working cylinder delivers while the equilibration cylinder is filled simultaneously. The equilibration cylinder serves as the reservoir and delivers while the working cylinder performs the intake stroke.

  • The sensors in the flowmeter measure and control the partial flows of the pump blocks.

  • The partial flows are combined in the fluidic Tee piece at the flowmeter outlet. The combined flow leaves the flowmeter with the selected target flow rate and solvent composition.