The compressibility compensation default settings are 50 × 10-6 /bar (best for most aqueous solutions) for pump head A and 115 × 10-6 /bar (to suit organic solvents) for pump head B. The settings represent average values for aqueous solvents (A side) and organic solvents (B side). Therefore it is always recommended to use the aqueous solvent on the A side of the pump and the organic solvent on the B side. Under normal conditions, the default settings reduce the pressure pulsation to below 2 % of system pressure, which is sufficient for most applications. If the compressibility values for the solvents used differ from the default settings, it is recommended to change the compressibility values accordingly. Compressibility settings can be optimized by using the values for various solvents described in Solvent compressibility. If the solvent in use is not listed in the compressibility table, when using premixed solvents and if the default settings are not sufficient for your application, the following procedure can be used to optimize the compressibility settings:
Start channel A of the binary pump with the required flow rate.
Before starting the optimization procedure, the flow must be stable. Use degassed solvent only.
Check the tightness of the system with the pressure test.
Check the tightness of the system with the pressure test (see System Pressure Test Description).
Your pump must be connected to an Agilent data system or Instant Pilot, the pressure- and %-ripple can be monitored with one of these instruments.
Start the recording device in plot mode.
Starting with a compressibility setting of 40 × 10-6 /bar, increase the value in steps of 10. The compressibility compensation setting that generates the smallest pressure ripple is the optimum value for your solvent composition.
Repeat step 1 through step 5 for the B channel of your binary pump.
Solvent (pure) | Compressibility (10-6/bar) |
|---|---|
Acetone | 126 |
Acetonitrile | 115 |
Benzene | 95 |
Carbon tetrachloride Footnote: Please check section Solvent information | 110 |
Chloroform Footnote: Please check section Solvent information | 100 |
Cyclohexane | 118 |
Ethanol | 114 |
Ethyl acetate | 104 |
Heptane | 120 |
Hexane | 150 |
Isobutanol | 100 |
Isopropanol | 100 |
Methanol | 120 |
1-Propanol | 100 |
Toluene | 87 |
Water | 46 |
[1]Please check section "Solvent Information" for compatibility to your specific LC system.
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