Metrohm 884 Professional VA, Руководство - Краткие инструкции

Страница: 85 / 91

￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭￭
6 Troubleshooting
884 Professional VA
￭￭￭￭￭￭￭￭
77
Problem Cause Remedy
The reference electrode is
not filled sufficiently (inside
and outside). Top up the reference electrode (see Chapter
3.2.2.2, page 36) .
The reference electrode's
diaphragm is partially or
completely blocked (e.g.
from precipitation caused
by incompatible solutions
like KCl as a bridge electro-
lyte and HClO
4
as an elec-
trolyte in the measuring
solution).
Ensure the compatibility of the chemistry.
Replace the bridge electrolyte if necessary
(such as using a NaCl or KNO
3
solution in place
of KCl).
The electrolyte solution is
too old. Produce new electrolyte solution. Organic
additives may only last 1 day or less.
Unstable or abnor-
mally low base cur-
rent in the pA range
(with MME pro). The electrode drips contin-
uously.
￭
Check the MME pro.
￭
Adjust the needle and capillary.
￭
If necessary, replace the capillary or needle
(see the
Multi-Mode Electrode pro docu-
ment (8.110.8018XX) ).
The tapping mechanism on
the VA stand base is not
functioning correctly.
￭
Check the positioning of the capillary in the
MME pro. The capillary has to be centered
in the retaining screw.
￭
The retaining screw is too loose or tight-
ened too tightly: Use the wrench for the
MME (6.1247.220) to tighten the retaining
screw to the correct torque.
The gas pressure is set
incorrectly. Set the gas pressure (1 - 1.2 bar; 14.5 - 17.4
psi; 0.1 - 0.12 MPa).
The gas pressure is unsta-
ble. The gas pressure must hardly change during
the measurement. This can only be ensured if
a high-quality pressure relief valve is used and
the tubing connection between the pressure
relief and the instrument is not extended.
The concentration to be
determined is substantially
higher than assumed.
￭
Reduce the deposition time.
￭
If the application permits, change the elec-
trode type (e.g. HMDE to SMDE or DME).
￭
Reduce the sample volume.