Let’s explore the world of vacuum pumps!
Starting with units.
1 psi = 6.894757 kPa.
Cubic feet per minute (CFPM or CFM) is a non-SI unit of measurement of the flow of a gas or liquid that indicates how much volume in cubic feet pass by a stationary point in one minute. The lower the CFPM the better the suction. 1 cfm = 4.71945×10-4 m3 s-1
Our target vacuum quality is 10^-9 torr, or 1.33322368 × 10-7 pascals.
Lets look at the different types of pumps:
Now lets take a look at what’s available on ebay:
cryo-trap to prevent back flow from diffusion pump.
I think the idea setup would be chamber -> cryo-trap -> oil diffusion pump -> rough pump.