Metrohm 774, Инструкция по эксплуатации, Страница: 32 / 168

3 Introduction
774 Oven Sample Processor, Instructions for use 26
shift position
The sample rack can only be rotated when the lift is at or above the shift
position height.
The shift position should therefore be selected so that safe rotation of the
sample rack is always possible, i.e. it must be impossible to damage either
the needle or the rack when the rack is rotated. Please note that the condi-
tioning vessel is slightly higher than the other sample vessels.
The value can also be entered manually or accepted automatically, as de-
scribed for the work position - see above.
rinse position
The rinsing position defines a further height setting, which is used for condi-
tioning, i.e. penetration into the conditioning vessel. See the exemplary
methods given in the 774 Tutorial.
The value can also be entered manually or accepted automatically, as de-
scribed for the work position - see above.
special position
The special position can be used to define a further lift height.
No commands are linked with the defined lift positions. In principle they can
therefore be used with any lift heights which are to be stored.
special beakers (in sub-menu special positions)
Up to 8 special beaker positions can be defined for each sample rack; in a
normal method procedure these are not regarded as sample beakers. Spe-
cial beakers can be deliberately selected at any time. For example, they can
be used as conditioning beakers. See the exemplary methods in the 774
Tutorial.
The special beakers 'Spec.1' to 'Spec.8' can each be allocated a beaker
position from 1 up to [number of sample positions]. Position 0 stands for
"not defined". Special beakers are preferably set at higher rack positions in
order to be able to start the series of samples at position 1. In the standard
rack for the 774 Oven Sample Processor position 36 is already defined as a
special position for the conditioning vessel and should not be altered.
3.1.4 Dosing units
In order to be able to additionally automate the dosing-in of auxiliary solu-
tions or aspiration from the measuring cell it is possible to connect up to 12
dosing instruments to the 774 Oven Sample Processor via 729 Dosimat in-
terfaces. The 685 Dosimats and 700 Dosinos can be used for this.
The maximum dosing and filling rates as well as the tubing dimensions of
the inlet tubing can be defined for each dosing instrument.
dosing unit
Dosing unit for which the parameters are to be entered
(1–12, see page 65f).
max. rate
This value represents the maximum permissible dosing and filling speed
(mL/min) of the dosing unit. Depending on the viscosity of the medium to
be dosed in, this value should be selected so that as rapid a dosing as
possible is selected; however, the buret must still be filled without any prob-
lems and free from any air bubbles. The max. rate is an absolute limit; it
cannot be exceeded even during manual dosing.