The structure, working principle, and countermeasures for cavitation of self suction centrifugal pumps

1. Working principle of self suction centrifugal oil pump

1. Working principle of self suction centrifugal oil pump

The driving machine drives the impeller to rotate through the pump shaft, generating centrifugal force. Under the action of centrifugal force, the liquid is thrown towards the outlet of the impeller along the blade flow channel, and is collected and sent into the discharge pipe through the volute.

. The liquid obtains energy from the impeller, increasing both pressure and velocity energy, and relies on this energy to transport the liquid to the workplace. As the liquid is thrown towards the outlet of the impeller, a low pressure is formed at the center of the impeller inlet, creating a pressure difference between the liquid in the suction tank and the center of the impeller. Under this pressure difference, the liquid in the suction tank continuously enters the impeller through the suction pipeline and pump suction chamber

2. Structure and Main Components of Self suction Centrifugal Oil Pump

A self suction centrifugal oil pump is mainly composed of pump body, impeller, sealing ring, rotating shaft, shaft seal box and other components. Some self suction centrifugal pumps are also equipped with guide wheels, inducers, balance plates, etc.

3. Working principle and characteristics of mechanical seals

Mechanical seals, also known as end face seals, are dynamic seals used for rotating shafts.

. It relies on the pressure of the spring and sealing medium to generate appropriate compression force on the contact surface of the rotating dynamic and static rings, making these two end faces tightly fit (maintaining an extremely thin oil film between the end faces to lubricate the dynamic and static rings). Therefore, the medium has a high resistance when passing through, thereby preventing liquid leakage and achieving the purpose of sealing

Secondly, solutions to cavitation in self suction centrifugal pumps

The phenomenon of cavitation is generally difficult to avoid. If the design of self suction centrifugal pumps is reasonable, it can to some extent delay the occurrence of cavitation. In addition, using materials with higher hardness can also slow down the corrosion effect of cavitation.

. The fundamental measure to reduce cavitation in self suction centrifugal pumps should be to improve their own resistance to cavitation

During use, attention should be paid to daily operation and maintenance to improve work efficiency and reduce the occurrence of cavitation

(1) Reasonably calculate the installation elevation of the self suction centrifugal pump according to the formula

(2) The water flow velocity in the storage tank should be gentle and should not have large vortices or backflow. In addition, debris and sludge in the water storage tank should be cleaned up in a timely manner to ensure smooth water flow and balanced flow velocity

(3) The inlet pipeline should be as short as possible, and unnecessary components should be reduced. The diameter of the pipeline should be increased as much as possible to reduce the flow loss of the inlet pipeline. To ensure a uniform distribution of water flow velocity and pressure at the inlet of a self suction centrifugal pump, the horizontal length of the inlet pipeline should not be too short to prevent backflow and vortices of water flow

(4) When the self suction centrifugal pump is working, appropriate adjustment measures can be taken according to the specific situation to adjust the parameters of the self suction centrifugal pump, preventing the operating parameters of the self suction centrifugal pump from deviating significantly from its design range

(5) Enhance the inlet pressure of the self suction centrifugal pump to increase its cavitation margin, such as expanding the diameter of the outlet of the self suction centrifugal pump, and use auxiliary devices for pressurization to reduce the harm caused by cavitation

(6) Control the impurities and sediment content in the water source. If there are many impurities in the water, it will intensify the wear of the flow components and exacerbate the cavitation phenomenon of the self suction centrifugal pump. Therefore, measures should be taken to purify the water quality of water sources with high levels of impurities

(7) Improve the machining accuracy of the impeller and flow components. The higher the smoothness of the impeller surface and other flow components of a self suction centrifugal pump, the better its anti cavitation performance, and the less likely it is that cavitation will occur

(8) Strengthen the daily maintenance of self suction centrifugal pumps. If the flow components of the self suction centrifugal pump have corroded, anti-corrosion coatings can be used for repair treatment. Timely repair of impellers can greatly improve their corrosion and friction resistance, prolong their service life, and improve the performance and efficiency of self suction centrifugal pumps

(9) Try to reduce the operating speed of the self suction centrifugal pump as much as possible. Its cavitation performance is directly proportional to the square of the pump speed. Reducing the speed of a self suction centrifugal pump can to some extent slow down the occurrence of cavitation phenomenon

(10) Adding an appropriate amount of air to the self suction centrifugal pump can reduce the destructive force of bubble rupture, lower the vacuum degree inside the pump, and thus weaken the harm of cavitation. But the amount of air added should not be too much, otherwise it will affect the performance of the self suction centrifugal pump