4.2 Care and maintenance
Metrohm 838 Advanced Sample Processor
,
Service, maintenance, faults
65
4.2.3 Replacing the dialysis membrane
It may be necessary to replace the dialysis membrane in the following
cases:
•
Reduced yield in dialysis
•
Dried-out membrane or membrane damage as the result of
deposits or bacterial growth
•
Irremediable blockage of the sample channel (sample is no
longer able to be pumped through the dialysis cell)
Proceed as follows in order to exchange the membrane (see also
3.3.7):
1 Detaching the dialysis cell
Unscrew the four inlet resp. outlet capillaries from the dialysis
cell
37
and remove the cell from the cell holder.
Using the 6.2621.070 Allen key, fully undo the 5 screws
42
and separate the lower section
41
from the upper section
38
Remove the old dialysis membrane
40
.
2 Cleaning the dialysis cell, fitting the dialysis mem-
brane and fitting the cell back on
See
Chapter
3.3.7
Fitting the dialysis cell
.
3 Connecting the dialysis cell
See
Chapter 3.3.12
Connecting the dialysis cell
.
4 Conditioning the dialysis membrane
See also
Chapter 3.3.12
.
Immerse the two aspiratory tubings
68
and
72
(see Figure
24) into the acceptor solution (degassed ultra-pure water).
Switch on the peristaltic pump in
«
IC Net
»
.
Rinse the dialysis system for approx. 20 minutes with ultra-
pure water. Check whether solution is emerging uniformly at
the two inlet capillaries into the waste vessel.
Check all tubings from the supply vessels through the tubing
cartridges and the dialysis cell as far as the waste vessels for
escaping fluid. If fluid is escaping, at any point, the corre-
sponding connection must be tightened or replaced.
If air bubbles remain in the dialysis cell, unscrew the PEEK
capillary
76
(acceptor solution) and PTFE capillary
73
(sam-
ple) from the outlets
44 resp.
47 of the
dialysis cell and wait
until the air bubbles have disappeared. Then screw the tub-
ings back onto the dialysis cell.
Switch off the peristaltic pump.
