Schambeck SDS 9414I, Руководство по эксплуатации

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SDS 9414i HPLC Pump
Version: 2.2 (July 2007) Page: 28 / 45
A to B: suction of liquid during pressure p1
B to C: compressing the liquid from p1 to p2
C to D: delivery against pressure p2
D to A: changing from delivery to suction
The compressibility will effect the constant of the liquid delivery depending on the pressure. To
overcome this problem, the S 2100 is using a calculation program to correct the pressure
depending change of the flow rate. This calculation program corrects the compressibility as
well as the always existing leakage rate of the check valves, in relation to the actual pressure.
The processor is checking the back pressure every 0.1 seconds and corrects the piston speed
accordingly.
The calculation program is using the liquid with the smallest compressibility (water) as a factor
of 1.
As different organic solvents are showing a different compressibility, the processor needs this
information for the most accurate delivery rate. This information can be added through the
Compressibility Factor in the ANALYSIS PROGRAM dialog. As water has been normalized to
the factor of 1, all others have to be smaller than 1.
The following table shows the Compressibility Factors of the mostly used solvents:
Solvent Compressibility Factor
Water 1.00
Methanol 0.63
Ethanol 0.74
Propanol 0.72
Butanol 0.75
Acetonitril 0.68
Chloroform 0.58
Methanol:Water (1:1) 0.79
Ethanol:Water (1:1) 0.88
Ethanol:Water (3:1) 0.79
Buffer Solutions 1.00