- 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
- Alliance 2695 Separations Module
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
- 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.
- Review the compression test guidelines outlined in the following operator's guides:
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.
pressure fluctuation, pressure ripple