The selection of screw pump

The selection of screw pump should follow the principle of economy, rationality and reliability. If the design and selection is not well considered, it will bring trouble to the usage, management and maintenance in future, so the selection of a progressing screw pump according to the actual production needs, reasonable and reliable can ensure the smooth production, but also reduce the repairing cost. Following tips are brief introduction to the selection of screw pump:

1.Screw pump speed selection

There is a linear relationship between screw pump flow rate and rotating speed. Comparing the lower speed screw pump, although the high speed of the screw pump can increase flow and head, but obviously increase the power. high speed accelerates the abrasion between the rotor and stator, so it must make the premature failure of screw pump, and the length of high-speed screw pump stator is short which is easy-wearing and the service life of the screw pump will be shortened. 

2.The rotary speed can be reduced by reducer or stepless speed regulation mechanism

The rotary speed can be reduced by reducer or stepless speed regulation mechanism, so that the survey speed is maintained in a more reasonable range (300r/min) compared with the high-speed operation of the screw pump, the service life can be extended several times. 

3.Ensure that the debris does not enter the pump body

Wet sludge mixed with solid impurities can cause damage to the rubber material of screw pump stator, so it’s important to make sure that debris won’t enter into the cavity of the pump, a lot of sewage plant install a grinder before pump,  also some install grating devices or filter to block out the debris into the screw pump, the grating should be timely cleaned so as not to cause congestion.

4.Avoid feeding break 

Screw pump must not be allowed to operate in the case of feeding break, once it happens, the rubber stator will be burned due to instant high temperature caused by dry friction, so intact grinder and unlocked grille are one of the necessary conditions for normal operation of the screw pump, some screw pump has function of shut down due to sudden feeding break, due to the characteristics of the screw pump has a self-priming function which creates a vacuum chamber when feeding break, vacuum device can stop the operation of screw pump. A

5. Maintain constant outlet pressure

 Screw pump is a capacity type rotary pump, when the outlet end is blocked after the pressure will gradually rise, so to exceed the preset pressure then the motor load increased sharply. The load of the related parts of the transmission machinery will also exceed the design value. In serious cases, the motor will burn down and the transmission parts will break. In order to avoid screw pump damage, generally bypass relief valve will be installed at the outlet of the screw pump, to stabilize the outlet pressure so as to maintain the normal operation of the pump.