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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 6. 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.
NOTE 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.
1 Start the quaternary pump with the required flow rate.
2 Before starting the optimization procedure, the flow must be stable. Use
degassed solvent only. Check the tightness of the system with the pressure
test (see “Pressure Test” on page 82).
3 Your pump must be connected to a Chemstation or a handheld controller, the
pressure and %-ripple can be monitored with one of these instruments,
otherwhise connect a signal cable between the pressure output of the
quaternary 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.