Metrohm 746 VA Trace Analyzer - Manual (Page 438)

5.7.3 Alphabetical instruction list
746 VA Trace Analyzer / 747 VA Stand
5-287
SMDE Page: O, S Stand: M, A Abbreviation: SM
Instructions t/s Main parameters Auxiliary parameters
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## .. SMDE ..... Drop size ........
Function Switch on Static Mercury Drop Electrode (SMDE).
Application The SMDE is primarily used for sensitive measurements in which the
surface of the mercury drop must be renewed for every measurement.
Parameter Range; Default value / Meaning
Drop size 1...9; 4
Drop size
Setting of the size of the mercury drop. The area of the drop is
ca. 0.15 mm
2 ( 1 ) ... 0.60 mm 2 ( 9 ).
The set drop time t.drop important for certain parameter settings is
defined for the SMDE as follows:
t.drop = Drop.size × 40 ms
Description The SMDE instruction switches on the 6.1246.020 Multi-Mode Electrode
as a static mercury drop electrode. The SMDE combines the features of
the DME and HMDE: as with the DME, the drops are constantly
renewed, but during the measurement the drop area is constant as in the
HMDE case. In a subsequent voltage sweep, the Hg drops are knocked
off by the tapping mechanism after the time
t.step set in the measure-
ment mode.
t.drop t.step
t
F (Hg)
Area
(Hg)