Metrohm 807 Dosing Unit - Manual (Page 46)

5.1 Problems
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807 Dosing Unit
Problem Cause Remedy
Dosing cylinder does
not fit into the cen-
tering tube Dosing cylinder is canted
or attached at an angle on
the base of the cylinder. Dismantle the cylinder and reassemble the
dosing unit.
Dosing unit has a
leak on the distribu-
tor Distributor disc shows leak-
age. Clean valve disc and distributor disc (see Chap-
ter 4.1.2, page 32).
Dosing unit recog-
nized either not at
all or incorrectly. The dosing drive was not
attached correctly. ￭ Remove the dosing drive and then reattach
it once again.
￭ Check whether the dosing drive is correctly
seated.
￭ Switch the control instrument off and on
again.
￭ If necessary contact Metrohm Service Dept.
Dosing unit incorrectly
assembled. Check whether the nominal volume on the
housing and the effective cylinder volume
match one another.
Dosino becomes hot Dosing drive is overloaded.
Valve disc or dosing piston
is blocked. ￭ Switch off the instrument immediately.
￭ Disconnect dosing unit from the bottle and
tighten only slightly (see "Dismantling the
dosing system", page 21).
￭ Disassemble the dosing unit and clean all
of the individual parts (see Chapter 3.7,
page 21). Replace defective parts.
Fluid above the dos-
ing piston Worn-out or defective dos-
ing piston and/or cylinder. Replace dosing piston and cylinder.
Housing cannot be
closed. Spring clip inserted incor-
rectly. Remove the housing and insert the spring clip
correctly.
Liquid drips into the
bottle There is air in the cylinder. ￭ Check the ends of the tubing, in particular
that of the aspiration tubing.
￭ Tighten all of the tubing connections with
the wrench 6.2739.000.
￭ Check the locking mechanism of the hous-
ing. Suggestion: Remove the housing and
then reattach it.
The reagent degasses
excessively, e.g. released
air forms bubbles. ￭ Carry out [PREP] / [Preparing]
￭ Reduce the filling rate.
￭ Suggestion: Degas the reagent with ultra-
sound, nitrogen or in a vacuum.