Operating Principle - Agilent Technologies 1290 Infinity 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.
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