Metrohm 838 Advanced Sample Processor Manual - Manual (Page 74)

3.1 Sample racks
66 Metrohm 838 Advanced Sample Processor, Appendix
Special beaker positions 16 reserved rack positions with individ-
ual working heights, beaker radius and
beaker sensor test
The rack name is used for the unambiguous identification of a rack.
The standard name stored for the rack is the ordering number. In a
method, this can be assigned to a particular rack name (see Sec-
tion 2.3.1). The automatic rack recognition ensures that if an incorrect
rack is used this will be recognized and the user will be informed of this.
The code is used for automatic rack recognition. You must make sure
that this 6-place binary code coincides with the actual magnet code set
on the rack. Rack codes can be altered as required. However, they
must always be assigned to a single rack only. Avoid the use of the
predefined codes for the standard racks supplied by Metrohm, see also
p. 64.
The working position is used for defining the lift position at which a
sample is to be processed. This means that the ideal setting for a par-
ticular sample rack can be defined depending on the height of the
sample beakers. In manual operation this working position can be
moved to directly with the <END> key. In a run sequence this can be
programmed with
LIFT :1 : work mm
.
The rinsing position is used for defining the lift position at which, for
example, the electrode is to be rinsed. This means that the ideal setting
for a particular sample rack can be defined depending on the height of
the sample beakers. In a run sequence this can be programmed with
LIFT: 1: rinse mm .
The shifting position is used for defining the lift position at which the
rack can be rotated. If the lift is located below the shift position then it
will be moved automatically to the shifting height before the rack is ro-
tated. This safety feature prevents the electrode from being damaged
by rotational movements of the rack to a large extent. However, a pre-
requirement is that this shifting height is set correctly. In a run sequence
the movement of the lift to the shift position can be programmed with
LIFT: 1 : shift mm .
The special position is a further user-defined lift position. For example,
when pipetting with a robotic arm it can be selected so that the pipet tip
is located directly above the sample solution so that a separating bub-
ble (air gap) is formed. In a run sequence this can be programmed with
LIFT: 1 : special mm .
The beaker radius can be used to prevent a titration head from trying
to enter a beaker which is too narrow for it, which could damage the
electrode or sample beaker. By entering the beaker radius a Sample
Processor can decide whether a titration or transfer head on the lift will
“fit” into the particular sample beaker, see also Section 2.2.
A beaker sensor is not available for the 838 Advanced Sample Proc-
essor at this time.