Failure of any oil diffusion pump vacuum system may affect the performance or production capacity of the equipment. Misoperation of any valve will cause the diffuser pump oil to return to the vacuum chamber, thus polluting the vacuum chamber and products. Leakage holes in the preceding pipeline, inappropriate level of mechanical pump oil, or failure of the preceding pipeline valve will cause the preceding pressure to exceed the critical value. When the current stage pressure exceeds the critical value, the diffusion pump oil will quickly return to the vacuum chamber.
In many cases, the reflux of pump fluid is caused by equipment failure or improper operation steps. The easiest way to achieve these considerations is to achieve full automatic operation of the system. With automatic control and regular maintenance, perfect fault protection can be provided. And reduce the amount of reflux to a very small level of organic contamination.
1. no mechanical pump can directly pump the vacuum chamber to less than 13.3Pa pressure. Because when the pressure is less than 13.3Pa, it will cause mechanical pump oil vapor molecules to flow back to the vacuum chamber and cause pollution. If there is an oil and gas trap between the mechanical pump and the vacuum chamber, the mechanical pump is allowed to pump under 13.3 PA pressure.
2. If a liquid nitrogen cold trap is installed between the inlet of the diffusion pump and the high vacuum valve, the liquid nitrogen should not be added to the well when the pressure in the vacuum chamber is higher than 10-2Pa, otherwise excessive condensation of water in the cold trap will occur. Before adding liquid nitrogen to the cold trap, remove all the condensate from the cold trap tank to avoid freezing the water in the trap.
3. Before the diffusion pump (or oil booster pump) must be ventilated to the atmosphere because of the need, the pump oil should be cooled below the safe temperature to prevent oxidation of the pump oil at high temperatures.
4. Preventing the pressure of the diffusion pump from exceeding the critical value due to the leakage in the front pipeline, the improper height of the oil level of the mechanical pump or the failure of the valve in the front pipeline. When the current stage pressure exceeds the critical value, the pump fluid will quickly return to the vacuum chamber.
5. Diffusion pump is best equipped with thermal protection relay, when a water shutdown accident occurs, can immediately make the heater power off, and close the pump inlet valve, to prevent the pump liquid due to high temperature deterioration and reflux.
6. Diffusion pump should not exceed the maximum gas load capacity (maximum pumping capacity) under stable working conditions. Long-term operation in the pressure range of 15-10-1Pa should be avoided as far as possible, because the diffusion pump and rough pump have the maximum reflux rate in this pressure range.
7. When the diffusion pump works, it should always check whether the pump has local overheating, check the cooling water temperature, and increase the cooling water when the water temperature is too high.
8. The operating environment of the diffusion pump should meet the requirements as far as possible. If the room temperature is higher than 35 C and the humidity is greater than 80%, the performance of the pump will decline.
9. When the diffusion pump is working normally, if the vacuum gauge tube of the vacuum system is broken, or when the vent valve suddenly opens, the high vacuum valve should be closed immediately. Prevent oxidation of pump oil.
10. when the diffusion pump is stopped, it should be kept in vacuum and cooled by compressed air.