The structure, working principle, and usage precautions of self suction centrifugal pumps

≪ One> Structure and working principle of self suction centrifugal pump

1. Working principle of self suction centrifugal 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 by the volute and sent to the discharge pipe.

. 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 Pump

A self suction centrifugal 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

< II Precautions for using self suction centrifugal pumps

1. Stop the pump

1. Close the gate valve on the discharge pipeline

2. Stop the rolling of the self suction centrifugal pump

3. In cold seasons, the storage fluid in the slurry pump body and the water in the cooling chamber of the bearing body should be emptied to prevent freezing and cracking of the components

2. Start and Operation

1. Inch the self suction centrifugal pump and pay attention to whether the rotation of the pump shaft is correct.

2. Pay attention to any abnormal movements and oscillations during rolling

3. Pay attention to the readings on the pressure gauge and vacuum gauge. After starting, when the readings on the pressure gauge and vacuum gauge fluctuate for a period of time and become stable, indicate that the pump has been filled with liquid and normal infusion operations have begun

4. Before the self suction centrifugal pump enters the normal infusion operation and during the self suction process, special attention should be paid to the increase in water temperature inside the pump. If the process is too long and the water temperature inside the pump is too high, stop the pump to check the cause. 5. If the liquid temperature inside the pump is too high and causes difficulty in self suction, it can be temporarily stopped and the liquid in the discharge pipeline can be backflow back into the pump or directly replenished into the pump at the storage port on the pump body to cool down the liquid inside the pump, and then started

6. If the self suction centrifugal pump experiences intense oscillations and noise during the operation process, it may be caused by pump cavitation. There are two reasons for cavitation: one is the excessive flow rate in the inlet pipe, and the other is the high suction head. When the flow rate is too high, the outlet control valve can be adjusted to increase the pressure gauge reading. If there is a blockage in the inlet pipeline, it should be cleaned in a timely manner; When the suction head is too high, the installation height of the pump can be lowered appropriately

7. When the pump stops due to unforeseen circumstances during the operation process and needs to be restarted, the outlet control valve should be slightly opened (not fully closed), which is beneficial for the gas to be discharged from the outlet during the self suction process and ensures that the tip can be started under lighter loads

8. Pay attention to check if there is any leakage in the pipeline system

Preparation before starting the self suction centrifugal pump: Check the operation.

1. For the self suction centrifugal pump, according to the operation of the pump, choose calcium based butter and No. 10 engine oil for smoothing. If using a pump with smooth butter, regularly add butter to the bearing box. Choose a pump with smooth engine oil, and if the oil level is insufficient, add enough.

2. Check if the liquid storage inside the pump casing of the self suction centrifugal pump is higher than the upper edge of the impeller. If it is lacking, the liquid storage can be directly injected into the pump body from the liquid filling port on the pump casing. Operation should not be started in the absence of liquid storage, otherwise normal operation cannot be carried out and mechanical seals may be damaged

3. Check if the rolling parts of the self suction centrifugal pump are stuck or bumped

4. Check if there is any looseness in the bottom feet of the self suction centrifugal pump body and the nuts at each joint

5. Check the coaxiality and parallelism between the pump shaft and the motor spindle of the self suction centrifugal pump

6. Check if there is any air leakage in the inlet pipeline of the self suction centrifugal pump. If there is any air leakage, try to clean it up

7. Open the valve in the suction pipeline and slightly open (not fully open) the outlet control valve