Maintenance - Thermo Scientific Finnpipette Digital Guide D'utilisation

Evaporation loss can be significant with low volumes. To determine mass loss, dispense water
to the weighing vessel, note the reading and start a stopwatch. See how much the reading
decreases during 30 seconds (e.g. 6 mg = 0.2 mg/s).
Compare this to the pipetting time from taring to reading. Typically pipetting time might be 10
seconds and the mass loss is 2 mg (10 s x 0.2 mg/s) in this example. If an evaporation trap or lid
on the vessel is used the correction of evaporation is usually unnecessary.
The factor Z is for converting the weight of the water to volume at test temperature and pressure.
A typical value is 1.0032 µl/mg at 22°C and 95 kPa. See the conversion table on page 57.
Inaccuracy (systematic error)
Inaccuracy is the difference between the dispensed volume and the selected volume of a pipette.
A = V - V
A = inaccuracy
0
V = mean volume
V = nominal volume
0
Inaccuracy can be expressed as a relative value: A% = 100% x A / V
Imprecision (random error)
Imprecision refers to the repeatability of the pipettings. It is expressed as standard deviation (s)
or coefficient of variation (cv)
Standard deviation can be expressed as a relative value (CV) CV = 100% x S / V
When the Finnpipette Digital is not in use, make sure it is stored in an upright position. We
recommend a Finnpipette stand for this purpose.
The part # refer to exploded views beginning at page 58.
SHORT-TERM CHECkING
The pipette should be checked at the beginning of each day for dust and dirt on the outside
surfaces of the pipette.
Particular attention should be paid to the tip cone. No other solvents except 70 % ethanol should
be used to clean the pipette.
LONG-TERM MAINTENANCE
Annual pipette usage varies significantly among laboratories, and the types of substances being
aspirated and dispensed also vary tremendously among laboratories. In order to maintain proper
care of the pipette, it is the laboratory's responsibility to develop a proper maintenance program
that meets its specific needs and requirements.
The servicing procedure starts with the disassembly of the pipette.
DISASSEMBLING 0.2-50 µl PIPETTES
1. Press the tip ejector.
2. Insert the maintenance pliers under the ejector bar to release the
tip ejector.
3. Remove the tip cone by pressing with maintenance pliers.
4. Pull out the piston and the spring.
5. Keep the tip cone vertically and push out with
piston the rest of the piston assembly.
Then keep the tip cone upside down and tap all
parts from tip cone.
Remember keep all parts in order on table for
reassembly.
6. Clean the piston, the piston spring and the
O-rings with a dry napless cloth.
7. Check the tip cone for foreign particles.
s = standards deviation
v = mean volume
n = number of measurements

MAINTENANCE

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