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8 TROUBLESHOOTING
If there is a leak or the pipette is not accurate, check for the following :
The connecting nut is loose. Fig. 3B.
Tighten the connecting nut.
The shaft is cracked or scored.
Remove the tip ejector and inspect the shaft. For the PW2,
PW10 and PW20 models, if the shaft is damaged, the piston may also be damaged.
Replace the damaged parts (see Section 10). Whenreassembling the pipette, the nut
should be hand tightened
Chemical damage to the piston and seals
Replace the piston and seals (See Section 10).
Wash the inside of the shaft using distilled water.
Improper reassembly.
Disassemble the pipette and reassemble the pipette correctly. Fig. 3.
If there is liquid in the shaft, clean the pipette as follows :
Remove the tip ejector. Unscrew the shaft nut and rinse the shaft, piston, seal and O-ring with
distilled water. Dry these parts and reassemble the pipette.
Note : If necessary, the shaft, shaft nut and the tip ejector can be autoclaved for 20 minutes
at 121°C and at 1 bar pressure. The seal and the O-ring should not be autoclaved.
The outside of the pipette can be cleaned using a cloth dampened with isopropanol.
If there is an air bubble when the sample is aspirated :
Eject the sample into its original vessel.
Check that the tip is properly immersed in the same liquid.
Pipette the sample more slowly.
If the bubble appears for the second time, replace the tip.
If a problem continues after carrying out the above steps, send the pipette to your representative.
Before returning a pipette to a represen-tative, please ensure that the instrument is completely
free of any contamination (chemical, microbian or radioactive).
