Alliance compression check failure with 200-µL sample loop installed - WKB25932

SYMPTOMS

• Alliance fails compression test with 200-µL sample loop and 250-µL syringe
• Instrument passes all diagnostics using 100% methanol with 100-µL sample loop and 250-µL syringe
  • Successfully adjusted seals, and measurements are within specified criteria or range
  • High-pressure motor valves 1 and 2 pass leak test diagnostics

ENVIRONMENT

• Alliance HPLC System
• 2695 Separations Module

CAUSE

Compressible volume is increased when conducting the compression test with larger sample loops.

• The parameters for the compression test were much too tight at anything below 20-psi delta decay with the larger sample loop.

FIX or WORKAROUND

1. Adjust the compression test parameters according to the default parameters recommended in the operators guide.
   • Recommendation: use a max delta decay of 50 psi as the default.
   • Change other parameters, such as the target compression pressure, only as necessary when working with larger sample loops and/or different solvent compressibility.
2. Review the compression test guidelines outlined in the following operator's guides:
   • 2695 Separations Module Operator's Guide (71500269502)
   • Alliance e2695 Separations Module Operator’s Guide (715003794)

ADDITIONAL INFORMATION

Compression test passed with repeatable results with the 200-µL sample loop when delta decay was 50 psi and target compression pressure was 200 µL. This is within the acceptable range of parameters for characterizing the instrument using this diagnostic.