The pumps generally consist of centrifugal pump and positive displacement (PD) pump, PD pumps are used much less than centrifugal pumps, however it plays an important role in all fields, The positive displacement pump types are normally internal or external gear pump, twin or three screw pump, progressive cavity pump, rotary lobe pump, peristaltic hose pump, diaphragm pump, sliding vane pump and plunger pump. They deliver fluid in two main classes of rotary and reciprocating.

The positive displacement pumps are more efficient or economic choice than centrifugal pumps if any of below applications in your process:

1.Centrifugal pump will be very inefficient for viscous fluids, but positive displacement pump has not problem to deliver thick liquids.

2. Centrifugal pump shall be operated in best preferred range, when a lower capacity is required, running a pump off its best range can lead to more power consumption, damage to pump and overall poor performance. However, a positive displacement pump is more suitable for lower capacity requirement only to be given a lower constant speed.

3. Some gear pump and peristaltic hose pump, plunger pump are ideal choice for metering applications, they delivery constant flow related with shaft speed to easily meet process requirements.

4.When high pressure is required, the reciprocating plunger pump, screw pump or gear pump can better achieve that with simple structures than centrifugal pump.

5.The rotary lobe pump or screw pump, diaphragm pump generally run at lower speed compared to centrifugal pump, low speed pump is gentler on fluids like syrup, tomato paste and latex paint.

Due to limited demand, the scale of positive displacement pump manufacturers is smaller than that of centrifugal pump manufacturers, and they are not even as well-known. Fortunately, Shanghai Shenmech International Co., Ltd. is established to identify all professional screw pump, peristaltic hose pump, rotary lobe pump, plunger pump, gear pump and sliding vane pump plants in China, and cooperate to provide quality pumps for global customers.