The cleaning procedure includes the following:

  • Ultrasonic cleaning with pure isopropanol

  • Running-in the check valves in the pump at high backpressure

When

  • Once a month

  • Dirty or malfunctioning check valves

Items required

  • Syringe (12 mL), filled with isopropanol

  • Small beaker filled with isopropanol

  • Ultrasonic bath

  • Solvents suitable for your application (for purging)

  • Solvents suitable for the run-in procedure

    In most cases, you can use the solvents of your application. To avoid electrostatic discharge in the backpressure capillary, at least 20% water should be present in the 50/50 mixture of solvents A and B. If you are using water-free solvents like normal-phase solvents, use 80% isopropanol in water on both, channel A and channel B.

  • Appropriate backpressure capillary, generating about 75 MPa at a flow rate of 50 µL/min in water (for example, nanoViper capillary, fused silica, inner diameter: 20 µm, length: 350 mm)

Preparations

Remove the check valves that you want to clean.

Recommended: Clean the inlet check valves and outlet check valves of both pump heads at the same time.

Follow these steps

  1. In the direction of flow, fill the check valves with isopropanol, using the syringe.

  2. Place the check valves in the beaker. Clean them in the ultrasonic bath for 10 minutes.

  3. In the direction of flow, flush the check valves with isopropanol, using the syringe.

  4. Insert and tighten the check valves. Reconnect the U-tube or solvent line.

  5. Install the backpressure capillary on the pump outlet. Guide the free end of the capillary to the waste container.

  6. Have the pump deliver the solvents suitable for the run-in procedure:

    Start with 50% B and a flow rate of 10 µL/min. Increase the flow rate until the system pressure is about 90 MPa and run the pump for 20 minutes.

  7. Inspect the pump head and check valves for indications of leakage. Tighten leaky connections only when the system pressure is down to zero.

  8. Uninstall the backpressure capillary and reconnect the system as required by your application.

  9. Purge the pump using the solvent for your application.

  10. Test the pump for leakage. Run the script: E04 - Detailed Leak test (Pump).