Skip to main content

HPLC Pressure Fluctuating - WKB10722

Article number: 10722


  • Pressure fluctuating from 0-600 psi with and without column.
  • Priming does not help.
  • Peaks are eluting late.
  • Pressure dropout on plunger stroke
  • Loss of pressure
  • Sonicating check valves does not solve the issue


  • Alliance HPLC System
  • 2695/e2695/2795/2690/2790 Separations Module
  • 515 HPLC Pump
  • 1500 series


Faulty check valves.


  1. Replace the check valves with new valves of the correct type (See video below).  Standard check valves, 700000254
    1. PerformancePLUS CV Cartridges, R/S, 1/8-in (700000254)
    2. Check Valve Cartridges, R/S, 1/16-in (WAT270941)
    3. PerformancePLUS CV Cartridge, Ceramic, 1/8-in ( 700002399)
    4. Check Valve, Ceramic (700002333)
    5. Check Valve Cartridge, R/S , Titanium (700002255)
    6. For 2790/2795, also replace Check Valve Cartridge, Ceramic, 1/16-in (700002761)
  2. If high delta psi or pressure fluctuation persists post new check valves replacement, then check system CD ratio (See video below.)  If CD ratio > 1.80, consider to rebuild pump with Alliance solvent manager PM kit, 700004073.
  3. Confirm that no more pressure drops are present.


Replacing Alliance system Check Valve Cartridges

Checking the C/D Ratio on an Alliance 2695 HPLC


pressure ripple

Not able to find a solution? Click here to request help.