User manual

1260 Nanoflow Pump User Manual 15
Introduction to the 1260 Infinity Nanoflow Pump
1
Introduction to the Pump
How Does Variable Stroke Volume Work?
Due to the compression of the pump-chamber volume each piston stroke of the
pump will generate a small pressure pulsation, influencing the flow ripple of
the pump. The amplitude of the pressure pulsation is mainly dependent on the
stroke volume and the compressibility compensation for the solvent in use.
Small stroke volumes will generate less pressure pulsations than higher stroke
volumes at same flow rates. In addition the frequency of the pressure
pulsations will be higher. This will decrease the influence of flow pulsations
on quantitative results.
In gradient mode smaller stroke volumes resulting in less flow ripple will
improve composition ripple.
The pump uses a processor-controlled ball screw system to drive its pistons.
The normal stroke volume is optimized for the selected flow rate. Small flow
rates use a small stroke volume while higher flow rates use a higher stroke
volume.
The stroke volume for the pump is set to AUTO mode. This means that the
stroke is optimized for the flow rate in use. A change to larger stroke volumes
is possible but not recommended.
When the pump is in the standard mode, the EMPV is fully closed. Total main
flow, up to 2500 µL/min, is directed to the LC system. Column flow
measurement/control is disabled. This mode is for non-capillary LC
applications.
In micro mode, the flow sensor measures and controls the column flow in the
range of 0.1 – 4 µL/min.
Flow measurement is based on the principle of mass flow temperature
sensitivity. The flow sensor consists of a heated tube with two temperature
sensors. As the mobile phase passes through the heated tube, the temperature
characteristic distributed over the two temperature sensors is evaluated. From
the temperature characteristic, flow rate accuracy is determined. The flow
sensor measurement is calibrated for specific mobile phases, which are
user-selectable.