BrandTech Scientific PLT unit Pipette Leak Testing Unit - Manual (Page 52)

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 there are scratches on the
piston.
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 an unsuitable tip was
used.
3. Close 3 channels with the caps provided, and test the individual channels
to localize the leak. Select the "single-channel" pipette type for this.
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?
What do the vertical progress bars in the display mean?
a b c
Testing multichannel pipettes
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.
Note on duration of tests
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