Analysis of Damage Factors of Dry Screw Vacuum Pump


  • What should I do if the vacuum pump fails to start?
    In the process of using the vacuum pump, whether it is a domestic vacuum pump or an imported vacuum pump, regardless of the quality, after a long time of work, if the maintenance is not performed in time and correctly, more or less failures will always occur. If the vacuum pump cannot be started normally due to long-term non-use or failure, a detailed analysis of the specific problem is required. The article mainly explains the reasons and troubleshooting methods of the vacuum pump cannot be started or cannot be started due to a fault.    1. The reasons for this failure due to the vacuum pump being unable to start are as follows:    (1) The drive motor voltage is incorrect or overloaded.   (2) Motor starter overload protection is too small or the set value is too low   (3) The fuse is blown.   (4) If the vacuum pump is equipped with an AC motor: the capacitor of the motor is damaged.   (5) Check the use of vacuum pump oil. The vacuum pump returns oil, the oil temperature is too low, and the oil has deteriorated. Fill the vacuum pump cavity with vacuum pump oil. Observe whether the oil has emulsified (white foam) or carbonized (blackened). The deterioration of the vacuum pump oil will affect the friction between the rotating blades and the rotor, and cause the blades to get stuck in the pump cavity.   (6) The vacuum pump or motor is stuck.   (7) The oil pump is worn out or foreign matter accumulates.   (8) The suction pipe is blocked.    2. The vacuum pump cannot be started and the maintenance solutions are as follows:   (1) Provide the correct voltage for the motor.    (2) Compare the setting data of the motor starter overload protection with the data on the motor nameplate, and correct it if necessary. If the ambient temperature is high: the set value can be increased by 5% based on the normal motor current.   (3) Check the fuse.    (4) Repair or replace the motor. (Professional technicians are required to operate)   (5) Replace the vacuum pump oil, disassemble the vacuum pump, and repair the cylinder block and other parts. If the blades are severely damaged, the vacuum pump blades need to be replaced.   (6) Make sure that the motor is turned off, and then disconnect the fan cover. Rotate the motor and vacuum pump by hand. If the hand plate does not move, please remove the motor from the pump and check the vacuum pump and motor separately. If the vacuum pump is stuck, it needs to be repaired (repair and inspection by professional technicians).   (7) Replace the worn parts of the oil pump, clean the foreign matter inside and outside the vacuum pump, and repair the pump (maintenance and inspection by professional technicians are required).   (8) Remove the suction pipe, operate the pump alone, touch the air inlet and outlet with your hands to see if the pump can work normally. If the pump cannot pump air at this time, it means there is a problem with the pump itself.    If the vacuum pump fails to start normally, find the cause or location of the fault. The inner cavity of the pump should also be disassembled in time for cleaning and inspection to prevent secondary damage to the pump outlet. If you don't know much about the inside of the vacuum pump, you need to find a professional vacuum pump maintenance manufacturer to perform professional vacuum pump maintenance.
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Analysis of Damage Factors of Dry Screw Vacuum Pump


1. Analysis of the cause of corrosion on the surface of the screw pump rotor
  The feed medium of the vacuum pump contains sulfur dioxide and water. The sulfur dioxide combines with water to produce sulfurous acid. Sulfurous acid has a corrosive effect on metals. To prevent corrosion of the rotor and pump cavity, a Teflon layer is applied to the surface of the rotor and pump cavity. The corrosion of the rotor and pump cavity indicates that the layer is damaged, and the sulfurous acid has corroded the pump cavity.
2. Analysis of the causes of damage to the Teflon layer of the rotor and pump cavity
   There may be three reasons for damage to the surface layer of the rotor and pump cavity:
   One is that solid particles enter the pump cavity, and the solid particles cause damage to the coating.
   The second is that chemical substances form colloids on the pump cavity and rotor, and the colloid is carbonized and hardened, destroying the coating of the rotor and pump cavity.
  Three are other reasons.
1. Analysis of the destruction of solid particles
   Inspect the pump inlet equipment and pipelines, no freely moving solid particles such as metal fragments, iron chips, etc. were found.
2. Analysis of the destruction of colloidal carbon deposits
Figure 1 is a photo of the attachment on the inner wall of the pump inlet pipe. The substance is dark brown. After analysis, it contains iron, carbon, oxygen, etc. It is a polymer substance such as butadiene and sulfolane. The substance is glued to the inner wall of the pipe. . If the substance adheres to the pump cavity and the surface of the rotor, it is easy to be carbonized and hardened, thereby destroying the surface layer of the rotor.
3. Analysis of process factors
    The gas phase outlet pressure of the vacuum pump is 80kpa(A), which is negative pressure, while the liquid phase outlet of the pump is normal pressure. Under normal conditions, the liquid at the outlet of the pump cannot enter the underground liquid tank normally, and a backflow is formed, which causes the accumulation of liquid substances at the outlet of the pump. , These liquid substances contain sulfurous acid, and the concentrated sulfurous acid liquid at the outlet of the pump will cause impact corrosion on the vacuum pump. It should be said that the backflow of the liquid at the outlet of the pump is the main cause of corrosion of the pump rotor and pump cavity.


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