BRAND PLT unit Mode D'emploi page 52

Testing multichannel pipettes
What do the vertical progress bars in the display mean?
A mark is added to the progress bar. This indicates the threshold value. This
corresponds to approx. ¼ of the volume tolerance.
a) The progress bar is completely filled in to the bottom: The instrument is
leak-tight.
b) The progress bar is filled in from the top only down to the threshold value
region: We recommend that a gravimetric test be performed.
c) The progress bar is filled in to a point well above the threshold value: The
instrument leaks. A gravimetric test should be performed, and if neces-
sary the unit should be sent for repair.
What to do if there are leaks?
If a dynamic test indicates the presence of leaks, one can attempt to localize
the source with further testing:
1. A static test should be performed next.
The pipette button is not activated, and the piston is not moved.
If the pipette is now leak-tight, this suggests:
– scratches on the piston
– defective piston seal
– unsuitable silicone oil
2. The dynamic test should be performed without a tip.
Adapter 3 can be reused for this.
If the pipette is now leak-proof, it is possible that:
– unsuitable tip
– defective tip cone
3. Testing a multichannel pipette: Close 3 channels with the caps provided,
and test the individual channels to localize the leak. Select the "single-
channel" pipette type for this.
Attention:
When using pipettes in which the pistons are greased with silicone grease,
only the manufacturer's recommended grease should be used!
When using pipettes in which the pistons are operated without silicone
grease, these should never be lubricated since irreversible damage might
then occur!
Please refer to the corresponding instruction manual.
Note on duration of tests
In the first test after switching the instrument on, a relatively large volume
must be pumped out, after which the instrument is given time to stabilize
(relaxation). Regularly switching between large and small pipette types leads
to longer test durations because the measurement pressure must be reset
each time.
The measurement time for pipettes up to 500 μl is generally 5 s, while it can
be 10 s for a volume of 1250 μl.
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b c
a