The cleaning procedure includes the following:

  • Ultrasonic cleaning with pure isopropanol

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

When

  • Dirty or malfunctioning check valves

  • Once a year

Parts and additional 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.

  • Backpressure capillary

    You can use any Viper capillary that can generate the backpressure indicated in the table with a flow rate between 1 mL/min and 4 mL/min. For example, you can connect the two Viper capillaries (length: 15 m each) from the Diagnostics tool kit with the connection union to obtain a 30 m capillary with 180 µm inner diameter.

Pump

Requested Backpressure

Approximate Flow Rate*

VC-pump

Approximately 62 MPa

Approximately 1.2 mL/min

VF-pump

Approximately 92 MPa

Approximately 1.8 mL/min

* Approximate flow rate with 80% isopropanol in water and 30 m capillary with 180 µm inner diameter

Preparations

Remove the check valves that you want to clean.

Recommended: Clean the inlet check valves and outlet check valves of all pump heads at the same time. To remove the check valves, follow the steps in Replacing the Inlet Check Valves and Replacing the Outlet Check Valves.

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. Reinstall the check valves. Follow the steps in Replacing the Inlet Check Valves and Replacing the Outlet Check Valves.

  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 1 mL/min. Increase the flow rate until the system pressure is well above 60 MPa (VC-pump) or 90 MPa (VF-pump) and run the pump for 20 minutes.

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

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

  9. Purge the pump, using the solvents of your application.

  10. Test the pump for leakage (see Testing the Pump for Leakage (General Test)).

  11. In the Chromeleon software, consider updating the Predictive Performance information for the check valves.