Metrohm 700 Dosino - Manual (Page 33)

3.2 Reagent exchange
700 Dosino, Instructions for Use
27
The maximum position of the piston is
never exceeded in dosing processes.
The remaining dead volume is therefore
always larger than any air bubble which
may remain after the 'PREP' function
has been carried out. This means that it
cannot escape into the tubing system
and affect the precision of the dosing
process. The air bubble remains in the
dosing cylinder.
3.2 Reagent exchange
Dismantling and cleaning the dosing unit when a regent is
changed is not normally necessary. The dosing unit is constructed
so that only a small exchange volume is present.
• Empty the dosing unit with the 'EMPTY' function of the control
instrument.
When the dosing unit has been emptied (with the 'EMPTY' func-
tion of the control instrument) it can be rinsed directly with the new
reagent.
• Fill the dosing unit with the 'PREP' function of the control in-
strument.
If precipitation or chemical reactions could occur when the new
reagent is mixed with the old one then an intermediate rinsing
stage should be carried out with an inert solvent.
If a reagent is not to be used for longer than one week then the
dosing unit should be emptied by means of the
'EMPTY' function
and the dosing drive removed.
air
bubble
PREP position
max. position
(10'000 im-
pulse)
zero position
(0 impulses)