Metrohm 789 Robotic Sample Processor XL - Manual (Page 101)

3.7 Sample racks
Metrohm Sample Processor, Operation 93
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 3.2.
The beaker sensor recognizes whether a beaker is present. At the
moment Metrohm Sample Processors support optical infrared sensors
built into each tower of the Sample Processor. In the rack definition the
beaker sensor can be switched on ( Tower) or off ( OFF) .
The setting for the beaker sensor can be made individually to suit the
particular samples and the individual special beaker positions, see be-
low.