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12 Agilent 1290 Infinity II Flexible Pump User Manual
1
Introduction
Operating Principle
Operating Principle
The pump head comprises two pump chambers in series with independent
high- resolution motion control. A pressure sensor in the flow path
monitors the pressure. The pump control uses this signal for minimizing
the pressure ripple in order to achieve highest flow precision. A stable
flow can be delivered even in case of eventual small internal leaks, which
can be compensated automatically. A heat exchanger between two pump
chambers strongly reduces thermal effects due to solvent compression
under very high pressures.
As solvents are compressed by the pump head and expand further down
the flow path, for example in the column, the volumetric flow is changed
depending on the compressibility of the liquid. Agilent control software
allows specifying pure solvents, pre- mixed solvents and solvent gradients.
Associated Agilent solvent libraries are used by the pump control for
enhanced flow accuracy, which is required for cross- instrument or
cross- system reproducibility and method compatibility.
A high resolution encoder unit is attached to the pump drives, which
divides a single turn into 65000 steps. Each step corresponds to a volume
of about 300 pL, which allows an extremely precise control.