Maintenance - Thermo Scientific Finnpipette Handbuch

Accuracy (systematic error)
Accuracy is the difference between the dispensed volume and the selected volume of
a pipette.
A = V - V
Accuracy can be expressed as a relative value: A% = 100% x A / V
Precision (random error)
Precision refers to the repeatability of the pipettings. It is expressed as standard
deviation (s) or coefficient of variation (cv)
n
S
S
=
i=1
Standard deviation can be expressed as a relative value (CV) CV = 100% x S / V
When the Finnpipette Fixed Volume is not in use, make sure it is stored in an upright
position. We recommend a Finnpipette stand for this purpose.
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
If the pipette is used daily it should be checked every three months. The servicing
procedure starts with the disassembly of the pipette.
DISASSEMBLING 1-40 µl PIPETTES
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1. Press the tip ejector.
2. Insert the maintenance pliers under the ejector bar to release the tip ejector.
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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.
8. Grease the cleaned parts with the lubricant that comes with the pipette.
9. Reassemble the pipette components.
All 1-40 µl: First, slide the spring 14, spring support 15 and tube 16 back on the piston.
Compress the spring with fingers by pressing piston and spring support 15 agains eachother.
11-40 µl: Slide bigger O-ring 17, smaller O-ring 18, spring support 19 (sharp edges
against spring) and small spring 20 on the piston.
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A = accuracy
0
V = mean volume
V = nominal volume
0
s
( V - V )
2
v
i
n
n 1
-

MAINTENANCE

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= standards deviation
= mean volume
= number of measurements
MAINTENANCE
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