The pipette is a kind of accurate instrument for quantitative transferring and weighing liquid in biology and chemistry laboratories. The most relative element to keep the pipette accurate is tightness. There are several main factors affecting the tightness of the pipette.
The first factor is the quality of the piston. The material of the piston is important and affects the quality of the piston. The piston can withstand the long-term friction with the sleeve.
The second factor is the quality of the sleeve. It should be not easy to bend, expand or shrink.
The third factor is the O-type elastic sealing ring. The O-type elastic sealing ring is consumables. You must check and replace it periodically, or the volume of the suction liquid will be wrong because of the leakage.
The fourth factor is the vacuum grease. The pipette needs to be repaired with grease after cleaning once there is some liquid entering into the pipette accidentally. Generally speaking, the vacuum grease is usually repaired by the manufacturer during calibration.