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Alliance 2695: System Lost Prime - WKB1630

Article number: 1630


  • Pressure fluctuations
  • No flow


  • Alliance 2695


There are several causes for a lost prime message: running out of mobile phase, air in the lines & check valves sticking are the most common.  The error occurs when there is 25psi or less for 50 strokes of the plunger.


  1. Check solvents if needed refill and prime system at 7.5mL/min for 5 minutes
  2. Check tubing for air bubbles if found prime that line at 7.5mL/min for 5 minutes
  3. If Solvents and tubing are ok, Reset the Gradient Proportioning Valve (GPV)
    1. On Main page, go to Diag
    2. Other Tests
    3. Scroll through the list to Turn off GPV, and press OK
    4. After GPV has been turned off, press OK to return to normal state
    5. Wet Prime the system
    6. Monitor flow and pressure if resolved continue with analysis
  4. If Resetting the GPV does not alleviate the issue, Sonicate check valves: To avoid solvent leakage first close the GPV, using steps 3.1-3.3 above.
    1. Sonicate check valves in water for 15 minutes
    2. Sonicate in methanol or acetonitrile for an additional 15 minutes
    3. Reinstall check valves
    4. Reset GPV select OK
    5. Prime unit at 7.5ml for 3 - 5 minutes
    6. Monitor flow and pressure if resolved continue with analysis
  5. If sonication does not work then replace the check valves


This problem may also be caused by the GPV.  All of the above should be tried first, then you may want to check the GPV by running solvent through each individual line and see if the pressures are stable.  If not, then the GPV may be the cause and should be replaced.  


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