Working principle of screw pump

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Due to the intermeshing of the screws and the tight fit between the screws and the inner wall of the cylinder, one or more sealed spaces are created between the pump’s inlet and outlet. As the screw rotates and meshes, these sealed spaces are continuously formed at the suction end of the pump, enclosing the liquid in the suction chamber. This liquid is then pushed continuously along the axial direction of the screw from the suction chamber to the discharge end, with the liquid trapped in each space being discharged sequentially. It is similar to a nut that is pushed forward continuously as it rotates on a thread – this is the basic working principle of a screw pump. The working principle of a screw pump is as follows: When the screw pump is in operation, the liquid is drawn in and enters the sealed space formed by the threads and the pump casing. As the driving screw rotates, the sealed volume of the screw pump increases due to the compression exerted by the threads, which in turn raises the pressure and causes the liquid to move axially. Since the screw rotates at a constant speed, the flow rate of the liquid output is also uniform. The characteristics of screw pumps are: low losses and good economic performance. It features high and uniform pressure, uniform flow rate, high rotational speed, and can be connected directly to the prime mover. Screw pumps can transport lubricating oil, fuel, various types of oils, and polymer materials, and are used for conveying viscous liquids. Transporting high-viscosity media: Depending on the size of the pump, it can transport media with viscosities ranging from 37,000 to 200,000 centipoise. Media containing particles or fibers: The particle diameter can be up to 30 mm (not exceeding the rotor eccentricity). The fiber length can be 350 mm (equivalent to the pitch of 0.4 turns of the rotor). Its content can generally reach 40% of that in a medium-type cellar; when the solids in the medium are in the form of fine powder, the maximum content can reach 60% or even higher, and it can still be transported. When a stable delivery pressure is required and the inherent structure of the medium should not be damaged, it is ideal to use a single-screw pump for transportation*. Severe vibration or noise from the pump: Causes: The water pump is not installed properly or it is installed at too high a height ； Motor ball bearing damaged ； The water pump shaft is bent, or it is not aligned or parallel to the motor shaft. Solution: Securely install the water pump or reduce its installation height ； Replace the motor ball bearing ； Correct the bent pump shaft or adjust the relative position of the pump and the motor. Overheating of the drive shaft or motor bearings: Causes include a lack of lubricant or damaged bearings. Solution: Add lubricant or replace the bearing. Water pump fails to discharge water: Cause: The pump body and suction pipe are not filled with priming water ； The dynamic water level is below the pump’s screen pipe ； Broken suction pipes, etc.