VWR VWRA613-6688, Manual

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7 MAINTENANCE & SERVICING
When the pipette is not in use it should be stored in an upright
position. The pipette should be inspected prior to use each day
for any dust or contamination on outside surfaces. Special
attention should be given to the tip cone. No solvent other than
isopropanol should be used to clean the pipette. If the pipette is
used daily, an internal parts inspection should be performed
every three (3) months.
7.1 DISASSEMBLY
The servicing procedure starts with the disassembly of the
pipette. Please refer to the spare parts lists for better
understanding of the components.
7.2 DISASSEMBLING THE LOWER PART
1. Press tip ejector pusher completely down and hold.
2. Pull down the tip ejector and release the tip ejector
pusher.
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• Calculate the inaccuracy and imprecision for all three
volumes as per EN ISO 8655-6 standards on the basis
of the following calculation
Mean Volume
Mean Weight
Balance Reading
number of reading
Conversion factor
[example Z=1.0040 µl/mg at 25°c and 1013 hPa]
Mean Value
Particular volume at which readings are taken
S = Standard Deviation
n = number of readings
S=
V = Mean Value
i=1
n
∑ ( Vi - V)
2
n - 1
CV% = 100 · S
_
V
Compare the results to the
limits in the earlier tables
(Page
) # 4, 5
6.3.1 CONVERSION OF WEIGHT READINGS TO VOLUME
6.3.2 CALCULATION FOR IN-ACCURACY (SYSTEMATIC ERROR)
6.3.3 CALCULATION FOR IMPRECISION (RANDOM ERROR)