The Selection Principle Of Volumetric Pump, Such As Screw Pump And Gear Pump

- May 22, 2018-

In any application, it is necessary to understand the basic requirements of the screw pump. Such as: entry conditions, the required flow, differential pressure, temperature and fluid properties, such as viscosity, and corrosion resistance, abrasion resistance, shear sensitivity of these conditions must be determined all down, and then you can choose single screw pump, double screw pump or three screw pump.

The gear pump can work well under the right suction conditions. In fact, the biggest problem in the problem of gear pumps can be traced back to poor suction conditions. Due to the ability of the gear pump to push the liquid far more than the ability to absorb the liquid, the inlet conditions should be kept within the pump's capacity.

Differential pressure is also a key part, especially in terms of energy saving and pump life, using smaller pipe diameters and longer pipes.

The author works for tianjin hanno industrial pump.

Laying length can reduce the initial cost of the system, but it can also lead to high pressure difference in the pump. This high pressure difference will be converted into energy consumption and may shorten the service life of the pump, which means higher operating costs and lower efficiency.

The required liquid properties are usually known, and the important thing is to know how a given pump affects these properties. The vast majority of users are willing to let the fluid from the pump stay the same when it enters the pump. The compatibility, viscosity, shear sensitivity and the presence of certain substances or solids are of great importance to the proper selection of pumps.

Centrifugal pump and screw pump.

Once the basic requirements are met and the liquid properties are known, the pump selection can begin. Pumps are usually divided into two basic categories: kinetic energy pumps (the largest of which are centrifugal pumps) and positive displacement (PD) pumps. According to the Commerce Department, about 70 percent of all pump sales are kinetic energy pumps, while the remaining 30 percent are volume pumps. When choosing a pump, the first step is to determine which one is more suitable for your needs in the centrifugal pump and the three-screw pump.

Since the main industrial pump is a centrifugal pump, many people consider the centrifugal pump first. The cost of centrifugal pumps is usually lower than that of the gear pump, and is also the correct gear pump type that should be used in many cases. Each pump is stirred in a different way, and each pump has its own operating characteristics and curves. However, it is important that the centrifugal pump can affect the flow rate of the liquid, thus causing some pressure at the outlet. In contrast, a twin-screw pump stirs a liquid and takes a specific amount of liquid and sends it from the entrance to the vent. For centrifugal pumps, pressure is formed first, resulting in flow. For the volume pump, the flow is formed first, and then the pressure appears.


To be able to select the most suitable type from each screw pump, it is important to understand the difference of working characteristics of the three screw pumps. When you look at its performance table (figure 1a), you can see how different it works. The centrifugal pump is dependent on the variable flow rate of pressure (or head), while the volume pump has more or less constant flow phenomenon, which is independent of pressure.


Viscosity plays an important role in the mechanical efficiency of single screw pump. Since the centrifugal pump is running at the speed of the motor, its efficiency will decrease with the increase of the friction loss in the pump.