Compressibility Compensation - Agilent Technologies 1220 Infinity II LC User Manual

5
Solvent Delivery System Description

Compressibility Compensation

Compressibility Compensation

Principles of compressibility compensation
The compressibility of the solvents in use affects retention-time stability when
the back pressure in the system changes (for example, ageing of the column).
To minimize this effect, the pump provides a compressibility compensation
feature that 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 compressibility compensation, the following happens during a stroke
of the first plunger: the pressure in the plunger chamber increases and the
volume in the chamber is compressed, depending on backpressure and solvent
type. The volume displaced into the system is reduced by the compressed
volume.
When a compressibility value is set, the processor calculates a compensation
volume that is depending on the backpressure in the system and the selected
compressibility. This compensation volume is added to the normal stroke
volume and compensates for the previously described loss of volume during
the delivery stroke of the first plunger.
92 1220 Infinity II LC System User Manual