Screw pumps are divided into according to the number of screws.

Single screw pump – a pump in which a single screw engages and rotates in the internal thread groove of the pump body.

Twin screw pump – a pump in which two screws mesh with each other to deliver liquid.

Three screw pump – a pump in which three screws mesh with each other to deliver liquid.

It is a single screw transport pump. Its main working parts are the screw with eccentric helical body (called rotor) and the screw bushing with double-line helical surface on the inner surface (called stator). Its working principle is that when the motor drives the pump shaft to rotate, on the one hand, the screw rotates around its own axis, on the other hand, it rolls along the inner surface of the bushing, so as to form a sealing chamber of the pump. Each time the screw rotates, the liquid in the sealing cavity is pushed forward by a pitch. With the continuous rotation of the screw, the liquid is pressed from one sealing cavity to another in a spiral manner, and finally the pump body is extruded. Screw pump is a new type of liquid conveying machinery, which has the advantages of simple structure, safe and reliable operation, convenient use and maintenance, continuous and uniform liquid discharge, stable pressure and so on.

Twin screw pump is composed of driving screw and driven screw with one end driven by prime mover extending out of the pump. The driving screw and the driven screw have threads in different directions. The screw fits closely with the pump body. The driven screw is driven by the driving screw through the synchronous gear. A sealed chamber with constant volume is formed between the screw sleeve meshed with each other on the master-slave moving shaft and the pump body or lining sleeve, and the medium is sent to the outlet of the pump with the rotation of the screw shaft, so as to realize the purpose of pump delivery.

Twin screw pump can be divided into built-in bearing and external bearing. In the structural type of built-in bearing, the bearing is lubricated by conveyor. The working chamber of twin-screw pump with external bearing structure is separated from the bearing. Due to the structure of the pump and the side clearance between the screws, it can transport non lubricating media. In addition, the synchronous gear is adjusted so that the screw does not contact, and half of the output torque is transmitted to the driven screw. Like all screw pumps, the external bearing twin-screw pump also has self-priming capacity, and most pump conveying elements are arranged symmetrically, which can eliminate axial force and have great suction height.

Twin screw pump series products are divided into single suction twin-screw pump and double suction twin-screw pump. This series of products has a special screw profile and supporting special structure. It is widely used in petroleum, chemical industry, metallurgy, steel, electric power, shipbuilding, pharmacy, food, building materials and other industries. It is unmatched by other pump products in terms of many applicable media, wide transmission range and complex application conditions. These characteristics also make this series of pumps have potential application and development prospects.

1. The conveying liquid is stable, without pulsation, stirring, small vibration and low noise.
2. It has strong self-priming performance. When multiphase mixed transportation, the gas content is not higher than 80% and the sediment content is not higher than 500g / m3
3. The external bearing structure adopts independent lubrication and can transport all kinds of non lubricating media.
4. Driven by synchronous gear, there is no contact between the two rotors, even if it idles for a short time.
5. The pump body is equipped with a heating jacket, which can transport various clean or low viscosity or high viscosity media containing small solid particles (generally the particle diameter is less than 0.12-0.2mm)
6. The correct selection of materials can even transport a lot of corrosive media.
7. Double suction structure, no axial force on the rotor.
8. The shaft end adopts mechanical seal or bellows mechanical seal, which has the characteristics of long service life, less leakage and wide application range.

Some positive displacement pumps can run dry. For example, there is no part to be lubricated or there is no tight clearance between parts. Since the hose is lubricated in its own fluid bath, the peristaltic pump can run dry. However, positive displacement pumps such as screw pumps should not run dry.

Each pump has an NPSH (net pressure suction head) to ensure reliable and trouble free operation without damage due to cavitation. Therefore, the design of the system shall ensure that there is sufficient margin between npsha (available net pressure suction head) and NPSHr (net pressure suction head is required).

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Huanggong group is a leading manufacturer of screw pumps in China. If you have specific application needs, please feel free to contact our expert team, and we can provide you with professional selection services and consultation.

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