When the autosampler injects samples, or switches valve positions, the pressure of HPLC pump drops and get pump error 3 or 4

When autosampler (AS-700) swithch the injection valve position, the pressure normally drops about 1 to 2 MPa. This is because the sample loop is not induced high pressure while it is at load position which the loop is offline  from the pump to column. Slower flow rate gives deeper pressure drop.

However, if the pressure drops significantly such as 4 or 5 Mpa or more, the pump can stops while or after the valve switches.  Possible causes:

1. Tubing connection is wrong. Please confirm all tubing is connected as the diagram on the autosampler.

2. Using in appropriate method file. If the air segment is too large, pressure drops significantly.

3. Tubing connection is wrong. Please make sure all tubing including sample loop has margin from the fitting. A gap between port and tubing will result in a lot of dead space.

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