Metrohm 846 Driver Toolbox - Manual (Page 10)

1.3 Metrohm 700/800 Dosinos and Dosing Units
6 Dosing Interface USB Toolbox, Overview
Fig. 5 Function: dosing/filling
1.3.1 Dosing/Filling the dosing cylinder
When the liquid is ejected push rod
9 of the 800 Dosino pushes
dosing piston 12 in the cylinder downward. The liquid in cylinder 13
is forced through the valve disk in cylinder base 14 into one of the
four openings in distributor disk 15 , depending on the valve disk
position. In distributor 17 the liquid is transferred to a dosing port
16 .
When the valve disk has been switched (see below), i.e. rotated,
then liquid is aspirated in the opposite direction through a different
port by pulling dosing piston
12 upward with push rod 9 of the
drive.
As the dosing units are exchangeable the coupling of push rod
9
has a slight mechanical tolerance that comes into effect when the
direction of motion of piston
12 changes. In automated processes
the drive compensates mechanically for this tolerance.
The piston movements are controlled by the accurate electronic
precision engineering of the drive which, independent of the cylinder
volume, has a resolution of 10 000 increments throughout the whole
piston stroke.
9
12
13
14
15
16
17