1. Poor air tightness, large error in liquid volume measurement 

If the interface between the suction head and the pipette is not properly sealed, gaps will occur, allowing air to enter the interior when drawing liquid. As a result, the actual amount of liquid drawn is less than the set value. When discharging the liquid, the internal pressure is unstable, preventing the complete discharge of the liquid. The quantitative accuracy is severely compromised. During micro-detection, standard curve preparation, and reagent dispensing, significant data deviations occur, and the repeatability of parallel samples is poor, directly affecting the credibility of the experimental results. In some cases, the liquid may be drawn slowly, the liquid surface may shake up and down, and it is unable to be stably locked in place. 

2. The suction head is prone to falling off and dropping, thereby contaminating the samples. 

The interface size does not match, and the clamping force is insufficient. During the process of moving the pipette, shaking the test tube, and blowing and dispensing the liquid, the tip is very likely to come off and fall into the centrifuge tube, beaker, or sample bottle. On the one hand, this contaminates the entire sample to be tested, resulting in the invalidation of the experiment; on the other hand, the fallen tip with waste liquid will cause cross-contamination on the workbench and the instrument. If it is biological liquid or toxic reagents, it will also bring safety hazards. The process of picking it up is also prone to causing hand injuries. 

III. Liquid leakage and splashing pose risks to biological and chemical safety. 

When the sealing fails, when drawing viscous liquids, highly surface-tension reagents, or corrosive liquids such as acids and bases, the liquids will leak through the joint gap; during vigorous mixing and liquid discharge, the liquids will spray outwards. The spilled pathogen samples will cause aerosol contamination of the tabletop and the air, the corrosive reagents will burn the skin and corrode the experimental equipment, and the volatile toxic liquids will spread and endanger the respiratory health of the operators. 

IV. Damage to the pipette tip sleeve and internal piston structure 

If a larger-sized suction head is forcibly pressed and installed, long-term squeezing will cause the sleeve to deform and the snap ring to expand, making it impossible to fit the subsequent compatible suction head tightly. For a smaller-sized suction head, repeated insertion and extraction will easily wear out the sealing ring on the inner wall of the sleeve. Poor sealing leads to abnormal air pressure, unbalanced force on the piston, accelerated aging and wear of the internal springs and sealing rings. In mild cases, the feel of the pipette will become rough and the pressing operation will be obstructed. In severe cases, the piston will leak air and the entire instrument will be directly scrapped, significantly increasing the cost of instrument maintenance and replacement.