Diffusion vacuum pump features
For the general diffusion vacuum pump, the vacuum pump body is mostly made of straight cylinder; for large vacuum pumps, cone cylinder or convex cavity vacuum pump body is also used. Because cylindrical vacuum pump body is easy to process, it is widely used at present. The vacuum pump body with the diameter of D < 250mm is made of seamless steel pipe, and the vacuum pump body of large vacuum pump is welded by coiling 4 ~ 10mm thick steel plate into a cylinder, and the weld seam can not leak. The inner wall of the vacuum pump should be plated with nickel.
The convex cavity vacuum pump body can greatly increase the pumping speed without increasing the size of the vacuum pump mouth. The convex cavity vacuum pump body changes the straight cylinder vacuum pump body into a partial drum shaped convex cavity vacuum pump body. The processing method is still welded by steel plates. The bottom section of the vacuum pump is the same as the inlet diameter of the flange of the vacuum pump, but the vacuum pump body expands the vacuum pump chamber at the lower part of the inlet flange, and the enlarged diameter extends to the wall of the vacuum pump where the jet from the second stage nozzle is directed. Because of the convex cavity of the vacuum pump body, the pumping space is enlarged, the conductivity between the first and second stage nozzles is increased, and the pumping speed is also increased.
oil diffuser pump
Ultra high vacuum pump oil is also a very important problem. The improper surface temperature of the vacuum pump wall makes it difficult for the oil vapor molecules colliding on the inner surface of the diffusion vacuum pump to condense. The surface temperature of the oil layer flowing down the vacuum pump wall is higher than that of the vacuum pump wall, so it is easy to produce re-evaporation and form the oil vapor reflux. Therefore, the cooling efficiency of the vacuum pump wall is high.
Generally, spiral copper pipe is welded outside the vacuum pump wall or made into water jacket (or spiral steel wire can be installed in the middle of the water jacket). The cooling part of the vacuum pump is usually confined to the area where the steam flow can be ejected, so that the oil condensed from the above can get a higher heat before returning to the oil pan, so that the dissolved gas in the oil can be released, so as to prevent it from mixing with the oil vapor into the nozzles at all levels, affecting the vacuum of the vacuum pump.