Metrohm 711 Liquino - Manual (Page 148)

6.1 Dosing units and Dosinos
711 Liquino, Instructions for use 142
Emptying — but automatic
A comfortable function is also available for completely emptying the dosing
unit when a reagent is changed: '
EMPTY'.
In order to exchange the reagent to be dosed by the dosing unit with as little
waste of reagent as possible, i.e. with a minimum exchange volume (typical-
ly < 14 µL ), the dosing cylinder and tubing can be emptied completely.
1
4
2
3
Port 4
Port 1
Port 3
Port 2
Dosing cylinder
4-way stopcock
This is possible because with a Dosino and dosing unit dosing is
carried out from top to bottom, i.e. the reagent is discharged
downwards by the Dosino piston. Then air is drawn into the cyl-
inder and again discharged through the tubing. This results in the
whole tubing system being completely emptied.
•
Hold the tip of the connected tubing in a waste beaker.
• Press <EMPTY>.
• You can now select (except in the XDOS mode) whether the
excess reagent solution is to be emptied via the dosing tip
(Port 1) or into the storage bottle (Port 4). This is done by
pressing key <1> or <2>.
• When the dosing cylinder is empty air is drawn in via Port 4
the tubing is emptied. After this all the tubing and the dosing
cylinder are filled with air.
• If special port occupancies have been defined in the XDOS
mode they will be used.
In order to determine the optimal volumes for these two functions automati-
cally the Liquino must be informed about the size of the cylinder and the
volume contained in the connected tubing. The cylinder volume of the dos-
ing unit is automatically recognized by the 711 Liquino. As different sizes of
tubing can be used with the dosing unit the lengths and diameters of the
tubing must be defined. In the configuration menu of the 711 Liquino (under
'Dosing units') different types of dosing unit with different tubing dimensions
can be defined with their own identification (ID). The corresponding ID of the
dosing unit can then be given for a method. In this way when the method
has been loaded the optimal volumes for the PREP and EMPTY functions
will always be used.
If the Dosino is operated manually the ID of the dosing unit can be given
separately for each dosing connection. The definition can be made in the
configuration menu under '>Manual operation'.