Common faults and troubleshooting measures of the

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Common faults and troubleshooting measures of the diffusion pump pumping system

common faults and troubleshooting measures of the diffusion pump pumping system are as follows (see also table 1, focus on improving resource integration 5):

(1) if the diffusion pump pumping system does not leak, and the limit pressure of the system does not reach the expected result, it may be that the system design is unreasonable and the effective pumping speed is low; Or the vacuum gauge electrode is deflated and the vacuum gauge itself is limited by photocurrent, so low pressure cannot be measured

(2) if the pumping performance of the diffusion pump or unit gradually deteriorates after long-term use, that is, the limit vacuum degree and pumping speed decrease, while other conditions are normal, it is mainly because the diffusion pump oil gradually oxidizes and the quality deteriorates. At this time, the diffusion pump oil should be replaced. The oil change steps are as follows: first remove the diffusion pump, take out the pump core, clean and dry the pump core as required, and then correctly assemble and add new oil

(3) when the diffusion pump suddenly leaks into the atmosphere due to special reasons, such as the explosion of vacuum gauge, opening the vent valve of vacuum container by mistake or not closing the high vacuum valve, close the high vacuum valve immediately, stop the expansion, do not operate the computer, heat the pump and force the oil pan to cool. After the fault is eliminated, the pumping test shall be carried out, and whether the diffusion pump oil needs to be replaced shall be judged according to the results

(4) after the diffusion pump is disassembled and connected to the system, if everything in the system is pumped in strict accordance with the above operating procedures, it should be able to reach the original limit pressure of the pump; If the gap between nozzles is carefully and repeatedly adjusted, the vacuum degree should be improved. If the vacuum cannot be pumped up, first check whether the air leakage rate of the system where the pump is located exceeds the allowable value; At the same time, check whether the heater of the diffusion pump has higher requirements for the upstream material enterprises, such as whether it is burnt out, whether the power supply voltage is normal, and whether the cooling of the pump is normal. If all the above aspects are normal, it can be considered as a problem in the assembly of the pump core, such as misaligned installation, incorrect nozzle clearance, the pump core is not cleaned before assembly, the organic solvent is not dried, the pump oil is not enough or the pump oil with poor quality is loaded, and the heating power is adjusted incorrectly

(5) if the diffusion pump works normally all the time, and it is not the system that causes air leakage somewhere, and the pumping performance of the unit and the close technical exchange maintained at the 5th Academy of space technology suddenly deteriorate, it may be that the electric furnace wire of the diffusion pump is broken or the fuse is broken, so it should be checked and replaced in time

(6) if the front stage pump does not work normally or the extraction capacity is not enough, the diffusion pump will also work abnormally

(7) ambient temperature, humidity, cooling water temperature and other service conditions also have a great impact on the pumping performance of the diffusion pump. For example, when the ambient temperature is too high (more than 35 ℃), the performance of the diffusion pump begins to degrade

(8) incorrect adjustment of the heating power of the diffusion pump can also make the working state of the diffusion pump abnormal. When adjusting the heating power, it is best to find the appropriate temperature for the lowest oil return rate

(9) the oil vapor backflow pollution system can also make the limit pressure of the system fail to achieve the expected results, which can be improved by referring to the previous measures of vacuum technology

table 15 common faults and troubleshooting of oil diffusion pump pumping system

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