5 • Service
Doc. 155028-01 08/20
73
5.8
Replacing a Pump Piston Seal and Backup Seal
A damaged seal allows leakage past the piston, as well as leakage from the piston
seal wash housing. This can cause unstable flow rates and baseline noise, and may
make it difficult to prime the pump.
Preparation:
1. Rinse the pump flow path with deionized water. Direct the flow to waste by
opening the waste valve on the secondary pump head (see
). To
open the valve, turn the knob one-half turn counterclockwise.
2. After rinsing, close the waste valve.
To remove the pump head and piston:
1. Turn off the Dionex Easion power switch.
2. Disconnect the power cord.
3. Put on standard disposable laboratory rubber gloves (powder-free, particle-
free, and oil-free) before disassembling the pump head.
4. Disconnect all tubing connections to the pump head with the defective seal.
5. Using a 7/64-in hex key (P/N 068227), loosen the two screws on the pump
head. Remove the screws, and then carefully remove the head and place it on
a clean surface.
6. Slowly pull the pump head and allow it to separate from the housing.
Carefully disengage the head from the piston by pulling the head straight off
and away from its mounting studs.
Never disassemble the pump head with bare hands. Even minute
particles of dust or dirt on the check valves or piston can contaminate
the inside of the pump head and result in poor pump performance.
Lateral motion while disengaging the pump head from the piston may
break the piston.
Un mouvement latéral pendant la séparation de la tête et du piston
peut casser le piston.
