Vacuum pump maintenance experts guide how to judge whether the vacuum pump has air leakage

To tell the truth, the occurrence of many fault problems of vacuum pump has nothing to do with the geographical problems of users. Just like the air leakage of vacuum pump, this is its internal problem. Generally, what are the parts where the air leakage of vacuum pump is easy? In addition, if there is air leakage, how should we solve it? Before solving it, we should know whether the vacuum pump has air leakage. Therefore, this paper will be guided by vacuum pump maintenance experts on how to judge whether the vacuum pump has air leakage, and summarize several reasons for air leakage.


The parts prone to air leakage of the vacuum pump include the starting and closing parts of the weld, the intersection of two welds, the welding parts of bellows, pipe joint welds and brazing welds affected by movement. If the flange seal or dynamic seal is carefully cleaned and assembled reasonably before installation, this part is not easy to leak. Metal ceramic and metal glass sealing joints, such as leading out electrodes, high-voltage leads of regulators, pins, caps, etc. Welds affected by cold and thermal shock.



The vacuum pump maintenance expert guides how to judge whether the vacuum pump has air leakage, which is summarized as follows:


1. Check whether the gravity return water of the vacuum pump speed regulating feed pump can be introduced into the condenser. If the return water is small and the water seal bag cannot be sealed, pour the gravity return water of the feed pump into the trench.

2. Check that the vacuum damage door is closed without leakage.

3. Check whether there is air leakage at the place where the extraction pipe of the vacuum pump is connected with the cylinder. The vacuum of the leaked air decreases when the load decreases, and increases slightly after the load increases.

4. Check that the drain valve at the steam side of the condenser is closed without leakage.

5. Check whether the water level of low-pressure heater under negative pressure is normal and whether the drain door is tight.

6. Check that the water level gauge of the vacuum system is not broken or leaked.

7. Check whether the water seal, pipeline, flange or welded junction of the vacuum system valve are not tight, especially the pipeline and valve door from the expansion tank or boiler starting separator to the condenser.

8. Check the exhaust safety valve of low pressure cylinder of vacuum pump.


The vacuum pump maintenance manufacturer shows that the air leakage of the general vacuum pump is caused by the following conditions.

1) Loose sealing of vacuum pump: tighten all connecting bolts, tighten packing gland, and tightly wrap the connection between pipeline and instrument and other components. Or replace gaskets and packing. For air leakage, oil and lime can also be coated as temporary remedial measures.


2) Bearing skew: this phenomenon makes the impeller installed obliquely in the pump body. For the single acting pump, the axial clearance is uneven. When Ye Yan rotates, part of it will rub with the side cover and scratch the side cover and impeller end face, so as to increase the axial clearance. When the gas in the compression chamber passes through the increased gap, a large amount of gas leaks into the suction chamber, reducing the vacuum degree or exhaust pressure. At this time, remove the bearing for repair, and then install it correctly.


3) The front and rear side covers are not concentric: the front and rear side covers of the vacuum pump may have different axial degrees, and the consequences are the same as the bearing skew.


4) Vacuum pump heating: when the temperature of vacuum pump rises, the saturated steam pressure also rises, which will reduce the vacuum degree, but it has no effect on the exhaust pressure.

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