60 1200 Series Quarternary Pump User Manual
5 Optimizing Performance
Optimize the Compressibility Compensation Setting
Optimize the Compressibility Compensation Setting
The compressibility compensation default setting is 100 × 10
-6
/bar for the
quaternary pump. This setting represents an average value. Under normal
conditions the default setting reduces the pressure pulsation to values (below
1% of system pressure) that will be sufficient for most applications and for all
gradient analyses. For applications using sensitive detectors, the
compressibility settings can be optimized by using the values for the various
solvents described in Table 9 on page 61. If the solvent in use is not listed in
the compressibility tables, when using isocratic mixtures of solvents and if the
default settings are not sufficient for your application the following procedure
can be used to optimize the compressibility settings.
1 Start the pump with the required flow rate.
2 Before starting the optimization procedure, the flow must be stable. Use
degassed solvent only.
3 Your pump must be connected to a control software (e.g. ChemStation,
EZChrom, OL, etc.) or handheld controller with which the pressure and
%-ripple can be monitored, otherwhise connect a signal cable between the
pressure output of the pump and a recording device (for example, 339X
integrator) and set parameters.
Zero 50%
Att 2^3 Chart
Speed 10 cm/min
4 Start the recording device with the plot mode.
5 Starting with a compressibility setting of 10 × 10
-6
/bar increase the value
in steps of 10. Re-zero the integrator as required. The compressibility
compensation setting that generates the smallest pressure ripple is the
optimum value for your solvent composition.
When using mixtures of solvents it is not possible to calculate the compressibility of the
mixture by interpolating the compressibility values of the pure solvents used in that mixture
or by applying any other calculation. In these cases the following empirical procedure has
to be applied to optimize your compressibility setting.
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