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Introduction to the Quaternary Pump
Overview
chamber is pressed through the outlet ball valve into the second chamber.
The second plunger draws in half of the volume displaced by the first plunger
and the remaining half volume is directly delivered into the system. During
the drawing stroke of the first plunger, the second plunger delivers the drawn
volume into the system.
For solvent compositions from the solvent bottles A, B, C, D the controller
divides the length of the intake stroke in certain fractions in which the
gradient valve connects the specified solvent channel to the pump input.
For quaternary pump specifications, see Chapter 8 “Specifications”.
How Does Compressibility Compensation Work?
The compressibility of the solvents in use will affect retention-time stability
when the back pressure in the system changes (for example, ageing of
column). In order to minimize this effect, the pump provides a
compressibility compensation feature which optimizes the flow stability
according to the solvent type. The compressibility compensation is set to a
default value and can be changed through the user interface.
Without a compressibility compensation the following will happen during a
stroke of the first plunger. The pressure in the plunger chamber increases
and the volume in the chamber will be compressed depending on
backpressure and solvent type. The volume displaced into the system will be
reduced by the compressed volume.
Table 28 Quaternary Pump Details
Delay volume 800–1100 µl, dependent on back pressure
Materials in contact with mobile phase
MCGV PTFE
Pump head SST, gold, sapphire, ceramic
Active inlet valve SST, gold, sapphire, ruby, ceramic, PTFE
Outlet valve SST, gold, sapphire, ruby
Adapter SST, gold
Purge valve SST, gold, PTFE, ceramic, PEEK
Damping unit Gold, SST