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, premixed 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.
base-id: 5726986123
id: 5726986123