Metrohm 754 Dialysis Unit - Manual (Page 34)

4.2 Maintenance and servicing
754 Dialysis Unit
31
4.2.4 Shutdown
If the dialysis cell is to be switched off a long period of time the accep-
tor and sample channels should be rinsed with ultrapure water for ap-
prox. 10 min. Then remove the inlet and outlet leads from the dialysis
cell and block each of the openings 41 41, 42 42, 43 43 and 44 44 (see Fig. 7) with
a 6.2744.060 dummy stopper.
4.2.5 Replacing the pump tubing
Pump tubings are consumable material with a limited lifetime and
should be replaced at regular intervals (approx. every 2 weeks under
continuous use).
The working life of pump tubing depends to a considerable extent on
the contact pressure. This is why the contact pressure must be cor-
rectly set as described in section 2.3.3. If the pump is to remain
switched off for a lengthy period of time the tubing cartridges should be
raised completely by loosening snap-action lever 88 on the right-hand
side (the pre-set contact pressure remains unchanged).
To replace a pump tubing proceed as follows:
1 Remove old pump tubing
• Press contact pressure lever 55 on the tubing cartridge down
as far as it will go.
• Release tubing cartridge 44 from holding clamp 77 by pressing
down snap-action lever 88 and remove from mounting pin 10 10
on the 754 Dialysis Unit (see Fig. 1).
• Remove old pump tubing.
2 Insert new pump tubing
• Insert the new pump tubing 30 30 (6.1826.040) or 31 31
(6.1826.040) in the tubing cartridge as shown in Fig. 6. The
stopper 32 32 must click into the corresponding holder on the
left-hand side of the tubing cartridge.
• Place the tubing cartridge on mounting pin 10 10 and press
down on the right-hand side until snap-action lever 88 clicks
into position on holding clamp 77. Take care that no kinks are
formed in the pump tubing.
3 Set contact pressure
• Press contact pressure lever 55 upwards until the solution just
starts to be drawn in. Then press contact pressure lever up-
wards until it clicks once more to obtain optimal contact pres-
sure.