Metrohm 806 Exchange Unit - Manual (Page 24)

3.3 Mounting the components
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806 Exchange Unit
3.3.2 Mounting the flat stopcock
Figure 4 Flat stopcock
Mount the flat stopcock as follows:
1 Check whether the flat stopcock can be moved. Twist the lower and
upper part of the flat stopcock against each other. For mounting the
stopcock, move the lower part to the right as far as the limit stop, i.e.
in clockwise direction.
2 Check whether the switching lever on the exchange unit is directed
to the right.
3 Insert the stopcock into the holder (see Figure 2, page 6).
The rectangular recess of the stopcock is to be directed to the groove
on the edge (on the left side) of the holder.
4 Check whether the stopcock can be moved by the switching lever.
5 Rotate the switching lever to the right to the dosing position.
6 Attach the exchange unit onto the control device.
Types of flat stopcocks
There is a PCTFE/PTFE stopcock (6.1542..020, standard equipment) and a
6.1542.010 ceramic stopcock available, which can be ordered separately.
Generally, the ceramic stopcock is to be preferred if hard crystals can pre-
cipitate out of the solution. If only soft crystals precipitate or for reagents
only occasionally used, we recommend the PCTFE/PTFE stopcock. The
PCTFE/PTFE stopcock is subject to a certain wearing. This stopcock has to
be replaced more often than the ceramic stopcock.
We especially recommend the following type of flat stopcocks: