Metrohm 730 Sample Changer - Manuel (Page 14)

2.4 Arranging the Accessories
730 Sample Changer, Installation 11
Spray nozzles
When using a changer model with two pumps per tower, spray
nozzles (6.2740.020) may be used in combination with an aspira-
tion tip M8 (6.1543.170). Insert the spray nozzles into the sloped
borings of the titration head. Use Teflon tubings to connect them
to the distribution head. Each of the four outlets of the distribution
head must be plugged. Plug unused outlets with an M6 thread
stopper (6.1446.040) to avoid splashing of liquid during rinsing.
Fix the tubings in the guide chain. Chain links may be removed if
necessary (see below).
Insert the aspiration tip vertically into a boring (SGJ9) of the Macro
Titration Head. The Micro Titration Head offers also a vertical bor-
ing for the placement of the aspiration tip. Connect the tip with the
Teflon 4/6 tubing (6.1805.510) and a screw connector 4/6 mm
(6.1820.030) to pump 2 (valve marked with 'ê'). During the rinsing
procedure, first the sample is sucked off then the electrode is
rinsed in the empty vessel.
The pump heads of the diaphragm pump, the fittings and the cou-
pling rings are made of PVDF. PVDF is resistant to many chemi-
cals. Acetone, acetanhydride or dimethylformamide (DMF) should
not
be used. The diaphragm, and the inner parts of the valves
consist of PTFE and are resistant to most chemicals.
If your samples contain solids (e.g. silver chloride) or sticking sub-
stances, you should use the 772 Peristaltic Pump Unit in combina-
tion with the 731 Relay Box instead of the diaphragm pump inte-
grated into the changer.
The PE canisters (6.1621.000) are suitable for aqueous solutions.