1.The working principle of the pipette is divided into two types: internal piston type and external piston type.
2.The built-in piston is to replace the air of the same volume with the target liquid by the air pressure difference through the movement of the internal piston of the pipette. In this way, there is a long air column between the piston and the liquid, and there is a filter element in the middle, so the piston of the pipette is not polluted, and it is very convenient to replace the suction head. Common pipettes such as Genex, Adonis and Colour belong to this type.
3.The external piston contacts the piston directly with the target liquid. When the piston is pulled up, atmospheric pressure will squeeze the liquid into the suction head. In this way, there is no air gap between the piston and the liquid, and the air pressure is 0, which can avoid the imbalance of internal and external air pressure caused by liquid gas/vaporization, and can better deal with the liquid with poor fluidity. Such as Stepper continuous liquid separator.