20
Pump head repair
Replacing the ball valves
Dirty ball valves may not open and close correctly. The entire ball
valve is replaced. For replacement of the ball valves, the manu-
facturer recommends removing the pump head.
Prerequisite
• Pump has been flushed with water and isopropanol.
• Pump has been switched off.
Duration
About 10 minutes
Level of difficulty
Level 2 (1 = very easy to 7 = very difficult)
Process
Title
1. Loosen the capillary
connections (C, D) bet-
ween the two feed
chambers of the pump
with a wrench, alterna-
ting sides every revolu-
tion to avoid jamming
(due to tilting).
2. Loosen screw fitting of
the outlet and inlet side
(A).
3. Check seals (F) made of
advanced Teflon® and
replace if necessary.
4. Replace ball valve (G,
H), paying attention to
its alignment. Marking
ring in the ball valve
indicates the direction
of flow (see illustration).
The marking on the
ball valve has to be on
the bottom, as the flow
of eluent will otherwise
be blocked.
Fig. 20
Ball valves with marking
ring for the direction of
flow
