Five mistakes during Vacuum pump maintenance

1. Welding fully the outlet self-washing pipe of the pump body

Most of the vacuum pump flushing pipe will use the sealing medium itself through the pump inlet and the flushing pipe to introduce the sealing cavity flushing the sealing end face. Because the joint sealing gasket at both ends of the flushing pipe and the thread fit are easy to leak, sometimes the flushing fluid will erode the seal of the bellows. During maintenance, the flushing pipe will be directly removed and then the joint at both ends will be welded fully by electric welding. Without the flushing pipe, the flushing fluid will interrupt the temperature of the friction pair and increase, which will also shorten the service life of the mechanical seal.

2. Remove sylphon seal guide jacket

The sylphon type mechanical seal generally has a water guide jacket. The cooling water enters the outer side of the water guide jacket directly from the gland, and then flows out from the lower part of the sealing gland after friction. Cooling water can not only play the role of cooling friction pair, but also prevent the leakage of liquid in the sealing cavity. Vacuum pump maintenance personnel often remove the water guide jacket at will to save trouble, which will cause the cooling water to flow out of the sealing gland without going through the baffle.

3. Adjust the pump bearing bracket bolt when setting

In the maintenance of pump, put the rotor, bearing bracket and other components into the pump shell, adjust the axial position of the blade wheel by the gasket between the pump shell and the pump cover, after adjusting the position, fasten the pump shell and the pump cover with bolts., and then fasten the pump cover and bearing bracket together with bolts, and finally install the coupling and alignment. The motor should be adjusted during alignment by first adjusting the axial clearance and then the radial clearance. Some maintenance personnel will adjust the tightness of the fastening bolt between the pump cover and the bearing bracket to correct the motor because it cannot meet the requirements. This will cause noise and vibration due to the different fastening degree of the bolt, and will also cause the whole pump to be scrapped.

4. The sealing effect of Large amount of compression is better than small amount of compression

When install mechanical seals, many vacuum pump maintenance personnel tend to subjectively think that large compression is better than small compression sealing effect. However, the excessive compression of the mechanical seal leads to the excessive specific pressure of the end face, which leads to the rise of the temperature of the friction pair and the decrease of liquid film degree of sealing end face, resulting in the failure of the sealing. But the mechanical seal compression cannot be too small, if the compression is too small, it’s easy to cause seal leakage.

5. Immediate maintenance is better than no maintenance

Once the mechanical seal leaks in the process of use, many vacuum pump maintenance personnel think that it should be repaired in time. In fact, in some cases, the effect of immediate maintenance is not necessarily the best option. In the process of mechanical seal operation, although there are some abnormalities, in fact, there is no damage, may be the change of relevant parameters such as medium, poor cooling effect and so on. After a period of time, the relevant parameters of the medium will become normal.