Why gear pump is not suitable for conveying media with particles

Author: Lin Qiangxing, Shanghai Suofu Industrial Co., Ltd

Generally speaking, gear pump is suitable for conveying liquid medium without solid particles.

Gear pump is a positive displacement pump, which sucks and discharges liquid by the volume change generated in the process of rotating and meshing a pair of gears. If the gear needs to rotate, it means that there is a gap between the gear and the corresponding cavity. Because of the existence of these gaps, there will always be some liquid returning from the outlet high-pressure area to the inlet low-pressure area during the operation of the gear pump, which is the internal leakage of the pump. In order to reduce the internal leakage of the pump, the clearance between the gear and the cavity is very small. Generally speaking, the lower the viscosity of the transported liquid, the greater the pressure difference between the inlet and outlet, and the smaller the gap.

When delivering low viscosity liquid (such as water or other solvents), the pressure difference of our NP series micro gear pump can reach 20bar (2MPa), and the minimum clearance in the pump is controlled at about 0.02mm, which means that particles larger than this size will cause the pump to jam.

In addition, the gears are meshed with each other during operation, that is, the tooth surfaces of the gears are in contact with each other, and there is contact friction movement between the bearing and the shaft. If particles enter these parts, they will cause serious wear and reduce the service life of the pump.