Addtime： 2020-07-08 Browse times： 2323
Vacuum pump maintenance is not a problem for professionals, but many professionals have negligent omissions during maintenance. Today I will talk to you about five common sense errors that should be avoided in vacuum pump maintenance.
1. Welding dead pump body self-flushing pipe
The flushing tube of the vacuum pump generally adopts positive flushing, that is, the sealing medium itself is introduced from the pump inlet through the flushing tube into the sealing cavity to flush the sealing end surface, the purpose is to take away the heat generated by the mechanical seal friction pair, reduce the temperature of the sealing end surface, and prevent the deposition of impurities and solid particles And gas retention.
Since the gaskets at both ends of the flushing tube and the threaded joints are easy to leak, sometimes the flushing liquid may also erode the bellows seal. When repairing, the flushing tube is directly removed and the joints at both ends are welded to the end. Without the rinsing tube, the rinsing liquid is interrupted, impurities and particles in the medium gather and stick around the sealing cavity, and the operating conditions of the friction pair gradually become more complicated, which eventually causes the temperature of the friction pair to increase and shorten the service life of the mechanical seal.
2. Remove the bellows seal water guide sleeve
Bellows type mechanical seals are generally equipped with a water guide sleeve. The cooling water enters the outside of the water guide sleeve directly above or obliquely above the gland, and enters the cavity of the water guide sleeve and the shaft sleeve after the baffle. It flows out directly under the sealing gland. The cooling water not only serves to cool the friction pair, but also prevents liquid leakage in the sealed cavity. Because the gap between the bellows and the shaft sleeve is relatively small, impurities and scale formed in the cooling water are likely to accumulate on the inner surface of the bellows. In severe cases, the cooling water path may be blocked.
In order to reduce the troubles caused by dredging the cooling water channel, vacuum pump maintenance personnel often try to save trouble and remove the water guide sleeve at will. As a result, the cooling water flows directly out of the sealing gland without deflection, which makes the cooling effect of the friction pair surface worse, resulting in If the water temperature is too high, the scale will be serious. If it is serious, the bellows seal will be stuck, causing the seal to fail.
3. Adjust the pump bearing bracket bolts at the timing
When servicing the centrifugal pump, according to the assembly order of the parts, install the assembly composed of rotor, pump cover, bearing bracket, etc. into the pump casing, rely on the pump casing and the stop of the pump cover to ensure that the impeller ring and the pump body For the coaxiality of the mouth ring, adjust the axial position of the impeller with the gasket between the pump casing and the pump cover. After adjusting the coaxiality and the axial position of the impeller, fasten the pump casing and the pump cover together with bolts. Then use bolts to fasten the pump cover and bearing bracket together, and finally install the coupling and align it.
When adjusting the motor, adjust the motor. First adjust the axial clearance so that the two coupling halves are parallel, and then adjust the radial clearance so that the two coupling halves are coaxial. Some vacuum pump maintenance personnel often adjust the tightness of the tightening bolts of the pump cover and bearing bracket to adjust the motor when adjusting the motor cannot meet the requirements. The consequence of this is that the motor often produces due to the different tightening of the bolts. If the noise and vibration are serious, the whole pump will be damaged.
4. Large compression amount is better than small compression amount, and the sealing effect is better
When installing a mechanical seal, many vacuum pump maintenance personnel often subjectively believe that a large compression amount is better than a small compression amount, but this is not the case.
Excessive compression of the mechanical seal causes the specific pressure of the end face to be too large, resulting in an increase in the temperature of the friction pair. Failure. However, the compression amount of the mechanical seal should not be too small. If the compression amount is too small, the pressure of the medium will fluctuate or the pump will stop, which may easily lead to seal leakage. In actual maintenance, the compression amount of the mechanical seal shall be based on the value given in the manual of the mechanical seal.
5. Immediate repair is better than no repair
Once the mechanical seal leaks during use, many vacuum pump maintenance personnel often think that it should be repaired immediately. In fact, in some cases, the immediate repair effect may not be the best. During the operation of the mechanical seal, although there are some abnormalities, it is not actually damaged. It may be that the relevant parameters of the medium have changed, impurities have entered between the sealing surfaces, and the cooling effect is poor.
After a period of time, the relevant parameters of the medium are normal, the impurities entering the sealing surface are washed away, the stress and deformation are eliminated, and the leakage amount will be significantly reduced or even eliminated. Vacuum pump maintenance personnel must observe carefully and analyze carefully when the conditions of the mechanical seal are abnormal, and then take effective measures. This not only avoids the waste of replacing mechanical seals, but also verifies your ability to analyze and judge equipment failures, and continuously accumulates practical experience in vacuum pump maintenance, thereby gradually improving maintenance skills.
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