SM-FTN random errors: "Seal residuals force exceeds (wash)" , "Needle seal move exceeds limit (5.0)", and "Zp-Axis home h/w fault" - WKB250911

SYMPTOMS

• "Seal residuals force exceeds (wash)", "Needle seal move exceeds limit (5.0)", and "Zp-Axis home h/w fault" errors appear randomly
• The load cell at bottom of wash station responds to pressure and shows increased seal force value on ACQUITY Console with pushing down on wash station
• Needle wash and Purge lines have solvent in them
• Needle is not bent
• After PM or needle seal replacement
• Characterize Needle Seal is giving a constant of 11 N/mm or more
• Characterize Needle Seal results are random between 3 n/mm and 11 n/mm (including during injections)

ENVIRONMENT

• ACQUITY UPLC H-Class PLUS
• ACQUITY UPLC H-Class
• ACQUITY UPLC Sample Manager - Flow Through Needle PLUS (SM-FTN PLUS)

CAUSE

In the wash station, the Vespel Seal Support is in the wrong position of the spring (see the picture at the bottom of this article).

FIX or WORKAROUND

1. Open  ACQUITY Console > Replace Needle Seat.
2. Verify that the Vespel seal support is in correct contact with the spring;
3. Put it in the correct position if necessary.
4. After correction, characterize needle seal should give a constant of 8.40 n/mm.

ADDITIONAL INFORMATION