A rotary pump refers to a pump that changes the working volume through the relative motion between the rotor and the pump body, thereby increasing the energy of the liquid. A rotary pump is a rotary displacement pump with positive displacement properties, and its flow rate does not change with back pressure. The main types of rotary pumps include gear pumps, screw pumps, cam pumps, sliding vane pumps, rotary piston pumps, hose pumps, etc.

The selection criteria for cam rotor pumps should be based on the process flow, water supply and drainage requirements, and consider five aspects, namely liquid conveying capacity, device head, liquid properties, pipeline layout, and operating conditions

Flow rate is one of the important performance data for pump selection, which is directly related to the production capacity and conveying capacity of the entire device. When selecting a pump, it is based on flow rate and takes into account normal flow rate. When there is no flow rate, it is usually recommended to take 1.1 times the normal flow rate as the flow rate.

The required head of the device system is another important performance data for pump selection, and the head is generally selected by amplifying the margin by 5% -10%.

Liquid properties include the name of the liquid medium, physical properties, chemical properties, and other properties. Physical properties include temperature, density, viscosity, solid particle diameter, and gas content in the medium, which involve the system's head, effective cavitation margin, and appropriate pump type.

The pipeline layout conditions of the device system refer to some data such as liquid delivery height, liquid delivery distance, liquid delivery direction, suction side liquid level, discharge side liquid level, and pipeline specifications and their lengths, materials, pipe fittings specifications, quantities, etc., in order to calculate the system head and verify the cavitation margin.

There are many contents of operating conditions, such as suction side pressure, discharge side container pressure, altitude, whether the ambient temperature is intermittent or continuous, and whether the pump position is fixed or movable.