Metrohm 850 Professional IC Anion MCS - Manual (Page 82)

4.5 High pressure pump
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850 Professional IC – Anion – MCS
Caution
In order to spare the pump seals, the pump should not be operated dry.
Therefore ensure that the eluent supply is correctly connected and that
there is enough eluent in the eluent bottle each time before turning on
the pump.
4.5.2 Maintenance
Caution
Maintenance work on the high pressure pump may not be carried out
unless the instrument is switched off.
Pump head maintenance
An unstable baseline (pulsation, flow fluctuations) is in many cases the
result of contaminated valves (42-2), (42-3) or defective, leaking piston
seals on the high pressure pump. Proceed as follows for cleaning contami-
nated valves and/or replacing worn parts such as pistons, piston seal and
valves:
This maintenance work should be carried out at least once a year.
Removing the pump head
1 Turn off high pressure pump and wait until pressure is released.
2 Loosen the pressure screw on the inlet valve holder (17-2) and
unscrew the coupling (17-9), the pump head input capillary (17-7)
and the eluent aspiration tubing from the pump head.
3 Unscrew the pump head output capillary (17-13) from the pump
head.
4 Remove pump head from the pump housing by loosening the 4 fas-
tening screws (17-5) using the 6.2621.030 hexagon key. The main
piston is on the left (viewed from the front), and the auxiliary piston
is on the right.