Instruction Manual

3.1 Electrodes
797 VA Computrace – Software
37
Voltage step time
t
Hg drop
surface
Notes:
In the exploratory mode, the DME can be used for the meas-
urement modes DC, NP, DP and AC. In the determination mo-
de, the DME can be used for the measurement modes DP and
AC.
An advantage of the DME compared with the SMDE is that the
MME capillary is subjected to less mechanical stress.
A disadvantage of the DME compared with the SMDE and
HMDE is the higher mercury consumption and the lower sensi-
tivity as the electrode surface constantly changes during the
measurement phase.
SMDE
SMDE is an electrode mode of the Multi-Mode Electrode and
stands for Static Mercury Drop Electrode. It combines the fea-
tures of the DME and the HMDE: as with the DME, the mercury
drops are constantly renewed, but during the measurement the
drop surface is constant as in the HMDE case. Each mercury drop is
knocked off by a tapping mechanism after the
Voltage step time
set in the measurement mode.
Drop size [ 1...9 ; 4 ]
Size of the mercury drop (surface 0.15 mm
2
...0.60 mm
2
).
t
Voltage step time
Drop size
×
40 ms
Hg drop
surface