Simple topic? Rotary vane vacuum pumps in series

[stabmaster]

Hi. I am trying to achieve a partial vacuum of under 10 micron Hg and I noticed that the options for vacuum pumps become exponentially expensive. Normally there would be volumetric flow performance and efficiency requirements involved but this is simply a bench scale/proof of concept vacuum. I have a 25 micron 2 stage rotary vane type 2.5 cfm pump I hope to use. I understand the gas laws and such, so 2.5 cfm on the low pressure side will be about 2.5*(25/760) cfm on the high pressure side without adding a second pump. The aforementioned pump is best utilized as a roughing pump, right? The concern is oil moving into the vacuum chamber, correct?

Also, which pump types are going to work well at around 25 micron on the high pressure side, only need to achieve 5-10 micron on the low pressure side and preferably seals/excludes the potential oil breach from the roughing pump? I'm a novice on vacuum pumps but I'm not a complete idiot. Any help is appreciated.

 

[rutherford703]

10 micron Hg = 10 um Hg. No easy to reach that low vacuum!! I guess what you are talking about is millimeter instead of micron.

Why not use a ejector? Normally ejectors are used to create vacuum.