Checking The Compression Values - Thermo Scientific Vanquish VH-P10 Operating Manual

8 • Troubleshooting
8.4

Checking the Compression Values

When
Follow these steps
Page 198
The compression values of the pump head can provide valuable
information for troubleshooting.
You observe pressure pulsation or shifts in retention time.
1. In Chromeleon, check the Compression values for the pump head
(compression on the left side in the pump head = CompressionDrv1,
on the right side = CompressionDrv2).
The values indicate the compression of the last stroke in percent.
The compression value should be less than 100%.
♦
With isocratic conditions, the compression value should remain
stable.
♦
When running a gradient, the compression value changes
roughly proportional to the pressure curve.
If the value is close to 100%, the required precompression may not
be reached and pulsation may occur.
The table shows guide values for some solvents (pure solvent,
degassed) with the pump being purged and the pressure being
stable for some time. The values are linear to the pressure.
Pressure (MPa) Water
250 11% ± 7%
500 21%± 7%
750 30%± 7%
1000 39%± 7%
1250 47%± 7%
1500 55%± 7%
2. Take remedial action if required.
Compression value lower than indicated in the table
♦
Replace the outlet check valve.
♦ Compression value higher than indicated in the table
Compression in % with
Methanol
22% ± 7%
41%± 7%
57%± 7%
71%± 7%
82%± 7%
90%± 7%
Vanquish Pumps (VH-P10) Operating Manual
Acetonitrile
22%± 7%
38%± 7%
53%± 7%
66%± 7%
76%± 7%
85%± 7%