Metrohm 846 Driver Toolbox - Manual (Page 11)

1.3 Metrohm 700/800 Dosinos and Dosing Units
Dosing Interface USB Toolbox, Overview 7
4
Fig. 6 Function:
switching the valve
disk
1.3.2 Switching the valve disk
The dosing unit has four ports. Two of them are on the outer housing and two
on the bottom of the dosing unit. Depending on the position of black valve
disk
18 a connection between cylinder 13 and the opening of white
distributor disk 15 assigned to the port is made.
The drive attached to the dosing unit uses cam
10 to rotate centering tube
19 and therefore the whole inner cylinder unit with cylinder base 14 and valve
disk 18 which it contains. After a rotation of the cylinder unit the opening of
valve disk 18 points to a different opening in distributor disk 15 . This means
that a different port 16 has been selected for dosing (or filling).
1.3.3 Port assignment
Distributor 17 of a dosing unit has four freely addressable inlets/outlets (ports)
and an additional connection which leads directly to the lower side of
distributor
17 . This VENT port, which cannot be addressed by the 4-way valve
disk, is responsible for venting the storage bottle and can be fitted with a
drying tube.
Fig. 7 Dosing unit seen from below
The inlets and outlets (ports) of the 807 Dosing unit can be used in different
ways. This is an important precondition for complex liquid handling applica-
tions. Metrohm titrators (e.g. 808 and 809 Titrando) use a standard port as-
signment that is the most suitable one for titration applications.
Port 4
VENT
Port 1 Port 3
Port 2
15
10
19
14
16
18