Except for the sand pump as well as mission pump , the centrifugal pump is also an important pump kind. There are mainly two classification of the centrifugal pump. In the middle of the working of the centrifugal pump, depending on the vane wheel with high rotating speed, the fluid gains power to increase the intensify of the pressure under the function of the inertial centrifugal force. Before the working of the centrifugal pump, both of the bump and the inlet pipeline must be full of liquid medium to avoid the cavitation phenomenon.
Single stage single-suction centrifugal pump
This kind of pump is used to deliver clear water that is less than 80 degree and clean liquid that is close to the water. Its range of lift is 8—125m while its flow range is 4.5—362 stere per hour. This pump has easy structure and reliable operation. And it is easy to manufacture and maintain. It used to be a widely used centrifugal pump.
It has two styles, front opening door and back opening door. The front opening door is that the front of the vane wheel is pump cover, the back pump case, while as for the back opening door, the structure is opposite.
As for the front opening door, the inlet of the pump is on the pump cover, and discharge is on the pump case which is spiral casing. The one side of the pump spindle support on the bearings on the pump and the other side is called bracket part. And the vane wheel is placed on the bracket part. There is balance pipe on the vane wheel to balance part of the axial force. And the axial force that has not been balanced should be supported by the bearings. The bearings that need grease to lube are ball bearings. And the oil seal device adopts packing seal. The pressure water inside of the pump can send to the water seal cage through hole on the pump case to function as water seal.
The shield centrifugal pump
The shield pump is the commonly used in chemical plant and it belongs to single stage cantilever type centrifugal pump.
The shield pump is also called the glandless pump. This kind of pump is used for delivering liquid that is inflammable, explosive, poisonous, radioactive as well as expensive. And it can be used cycledly as high tension devices. Its structure is that the vane wheel of the pump and the rotor of the electrical machine are on the same axle and placed on the same sealed housing without coupling as well as sealing device, eliminating the leakage fundamentally. In order to prevent the touch of the delivering liquid and electrical part, it is possible to use stator and rotor of the electrical machine to separate the metal thin walled cylinder from the liquid. And the material of the shield cover should be corrosion resistant to reduce the extra power consumption of the motor. In order not to interfere the magnetic field of the electrical machine, the material of this metal thin walled cylinder uses nonmagnetic material. Because of the existence of the shield cover the gap between rotor and stator of the motor increases.
Shield pump has the advantages of close and simple structure, few parts, small occupation, reliable operation and no need to maintain for a long time. And its disadvantages are low efficiency, which is 26% to 50% lower than the centrifugal pump.