When

  • Damage to piston seals, leaky seals

  • Unstable flow rates or baseline noise

Parts required

  • Piston seals

  • Support ring

    Note that the support ring is not a wear part. You need not replace the support ring when you replace a piston seal. Replace the support ring only when applicable.

  • Seal wash seals (and seal-handling tool)

NOTICE

All pumps except VC-P21 and VC-P33: Whenever you remove the pump head, you must replace the seal wash seals.

Tools and additional items required

  • Syringe filled with isopropanol

  • Cleaning swab

  • Lint-free tissue

  • Seal-handling tool

Seal-handling tool
Figure: Seal-handling tool

No.

Description

1

Seal removal pin

2

Seal insertion pin

Preparations

  1. Remove the pump head (see Replacing the Pump Head).

  2. Remove the pistons (see Replacing the Pistons).

Follow these steps

  1. Remove the seal wash plate from the pump head if applicable.

  2. Pump head, seal wash plate removed
    Figure: Pump head, seal wash plate removed

    No.

    Description

    1

    Pistons

    2

    Seal wash plate

    3

    Seal wash bodies

    4

    Support ring

  3. Remove the seal wash bodies from the pump head.

  1. Remove the support ring.

    Gently tap the pump head on a clean work surface to make the support ring drop out.

    If the support ring does not drop out, use the seal-handling tool. With the insertion pin, push the seal-handling tool at a slight angle into the pump head and remove the tool. The support ring is removed together with the tool.

NOTICE

Do not use the seal removal pin to remove the support ring. The support ring can be removed from the tool only with difficulties.

  1. Remove the piston seal.

    With the removal pin, push the seal-handling tool into the pump head as far as it goes in and remove the tool. The piston seal is removed together with the tool. Once the seal has been removed, it cannot be reused.

  1. Required if you reinstall the support ring

    Clean the support ring from the inside and outside, using isopropanol, a cleaning swab, and a lint-free tissue.

  1. Pipette a few drops of isopropanol into cavity in the pump head, on the edge on which the piston seal will rest.

Pump head (left: no piston seal installed, right: piston seal installed)
Figure: Pump head (left: no piston seal installed, right: piston seal installed)

No.

Description

1

Edge on which the piston seal will rest

2

Piston seal installed

  1. Slide the support ring onto the insertion pin of the seal-handling tool.

  2. Slide the piston seal onto the insertion pin, with the open side of the seal facing away from the tool.

  3. Support ring and piston seal on insertion pin
    Figure: Support ring and piston seal on insertion pin

    No.

    Description

    1

    Support ring

    2

    Piston seal (open side facing away from the tool)

  4. With the insertion pin, push the seal-handling tool into the pump head as far as it goes in.

  1. Remove the tool from the pump head. The piston seal and support ring remain in the pump head.

Pump head, piston seals, and support rings installed
Figure: Pump head, piston seals, and support rings installed
  1. Insert the seal wash bodies into the pump head. Mind the correct orientation. The even side faces the pump head.

Orientation of the seal wash body
Figure: Orientation of the seal wash body

No.

Description

1

Side facing the seal wash plate

2

Side facing the pump head (even side)

  1. Replace the seal wash seals. Follow the appropriate steps in Replacing the Seal Wash Seals.

  1. Install the pistons. Follow the related steps in Replacing the Pistons.

  2. Install the pump head. See Installing the Pump Head.

  3. Observe the recommendations for new piston seals (see Recommendations for New Piston Seals).

  4. Inspect all flow connections on the pump head for indications of leakage. Tighten leaky connections when the system pressure is down to zero.

  5. In the Chromeleon software, consider updating the Predictive Performance information for the piston seals.

  6. Test the seal wash system and pump for leakage (see Testing the Seal Wash System for Leakage and Testing the Pump for Leakage (General Test)).

  7. Recommended: From the Chromeleon software, perform performance qualification for the pump:

    • Run the pump-specific Performance Qualification tests (PQ tests) (= Flow Precision Test and Gradient Accuracy Test). For details, refer to the Operational and Performance Qualifications manual.

    • When the tests are completed, execute the QualificationDone command.