Solutions To Common Problems In Vacuum Systems

---

What to do if steam appears?

First, in the process of vacuum drying in the electrical products industry, the vacuum system is required to be able to extract a large amount of water vapor and solvent in a certain pressure range, and at the end of the drying, a lower ultimate pressure must be reached.

Second, the principle of the steam treatment device of the vacuum system is that in the vacuum state, when the temperature of water or steam is higher than the boiling point, they enter the pump chamber as a gas. The slide valve pump itself is a heating source. The liquid ring pump provides a low pressure to the separator of the slide valve pump, so the water or other steam discharged to the separator is also in a vacuum state, and the temperature is high enough to keep them at In the gas state, any tiny droplets will be evaporated in the separator. The water or other steam discharged to the liquid ring pump is condensed and becomes part of the sealing liquid because the temperature in the liquid ring pump is relatively low. In order to prevent the steam from being condensed in the pump, the oil temperature of this pump must be high enough, generally set in the range of 60～75℃, and the oil temperature higher than 80℃ will cause the vacuum pump oil to be oxidized. This required oil The temperature can be controlled by automatically adjusting the amount of cooling water entering the slide valve pump.

Third, the advantage of the steam treatment device of the vacuum system is that it can treat a large amount of condensable gas or volatile gas, and the pumped steam will not be condensed in the pump, which reduces the corrosion of the metal surface. Avoid oil pollution, greatly reduce the number of oil changes, and significantly reduce operating costs. Eliminates performance degradation caused by oil contamination. It can maintain low working pressure in wet process.

Reasons for not reaching the required vacuum

First, the vacuum quenching furnace cannot reach the vacuum degree: it may be that the vacuum unit has insufficient pumping capacity, or it may be that the leakage rate is too high, or both.

Second, after pumping the vacuum chamber to a certain vacuum state, close the vacuum valve. If the vacuum count value rises quickly, the vacuum chamber leaks in most cases. At this time, the leak should be detected first and the leak should be corrected. If the vacuum count value rises very slowly, it may be that the vacuum unit has insufficient pumping capacity. The focus of the vacuum quenching furnace is to find the leakage of the vacuum pump and valve, or the vacuum pump oil is contaminated or oxidized, or the foreline pipeline is not well sealed, the pump oil is insufficient, or the pump oil is emulsified, and the shaft seal leaks. At this time, replace the vacuum pump oil or directly replace the vacuum pump.

Third, if the vacuum of the equipment drops rapidly in a short time. Generally, it is caused by the aging, scratches, and oxide scale falling off of the dynamic seals of the vacuum quenching furnace door, vacuum valve, and middle partition hotspot to the sealing line. The seals can be replaced by cleaning, and the valve can be manually opened for maintenance. If there is no problem, check the location of the interface between the vacuum chamber and the outside world, such as connecting flanges, water-cooled electrodes, pipes and vacuum tubes, etc. Sometimes the acetone leak detection method can be used to observe the vacuum change and carefully find the leaks.

Editor: Frank Lee

Copyright: SIMUWU Vacuum Furnace