Metrohm 761 SD Compact IC User Manual
Page 104
6 Notes – Maintenance – Faults
761 SD Compact IC / Instructions for Use 8.
761.1043
96
5 Clean/replace inlet valve 77
and outlet valve 78
•
Clean contaminated or blocked valves by rinsing with distilled
water, RBS solution or acetone.
•
If this does not have the desired effect, the valve can be dis-
mantled as shown in Figure 17. The valve components must
be pushed out of the housing using the tool 6.2617.020. The
individual components can then be rinsed with distilled water
and/or acetone, and the sapphire sphere cleaned with a pa-
per towel. Then reassemble the valve in accordance with
Figure 17. The components of the inlet and outlet valves are
identical. They are distinguished only by the positioning of the
sapphire sleeve 85 and the ceramic holder 87 (see Figure
17).
•
Valves which fail to function faultlessly after such cleaning
must be replaced.
•
When reinstalling the inlet valve 77 or outlet valve 78, on no
account may the two outwardly identical valves be inter-
changed. In order to determine which valve is which, note
that the fluid flows through the pump head from bottom to
top. The flow direction of the valves can be checked simply
by blowing through the clean valve. Both valves must be fitted
with the black face pointing in the direction of the pump head
If an inlet valve
is installed by mistake instead of the outlet valve
an extreme pressure build-up occurs within the working cylinder, and
this is not detected by the pressure transducer and will destroy the
piston seal
6 Fit the pump head
•
Reassemble the components of the pump head 24 as shown
in Figure 15. Tighten the screw 68 by hand. First screw in the
piston cartridge 72 fully and then tighten it a further
15° with a
spanner. Firmly tighten the two valve screw holders 79 with a
spanner.
•
Reattach the pump head 24 to the pump with the four secur-
ing screws. Tighten the screws when doing this with the Allen
key 6.2621.030.
•
Screw the connection capillary 25 back onto the pump head
•
Connect the PEEK capillary 55 back onto the aspirating capil-