There are two performance parameters of the screw pump: displacement and power.

The theoretical displacement of the screw pump can be calculated by the following formula: Qt = 60FTN M3/h; its internal leakage is generally represented by QS: qs = αP/σm.

When the pump is pressed a liquid with different viscosity, its displacement changes.

The relationship between displacement and viscosity can be represented by the following formula: Q2 = QT- (qt-Q1) (σ1/σ2) m

The axis power of the screw pump is generally the sum of the three parts of water power, friction power, and leakage loss power.

Water power refers to the energy passed to the liquid during the unit time, also known as the output power; the friction power refers to the friction loss caused by the liquid viscosity resistance; the leakage loss refers to the power loss caused by leaking the liquid from the low pressure at the high pressure. When the liquid viscosity transported by the pump is different, the axis power of the pump will be different.

Correspondingly, the disadvantages of screw pumps are relatively obvious: the processing and assembly requirements of screws are high; the performance of the pump is more sensitive to the viscosity of the liquid.