Harbor freight vacuum pump

[olddavid]

I have to disagree about whether "any" pump will reach the same level of vacuum. It is not just a matter of time. It is also a matter of how capable the pump is. Needless to say, some pumps are more able to reach a deep vacuum, and some may never be able to reach the same level as a more "precision" pump for lack of a better word. Needless to say, a multi stage pump will usually pull a deeper vacuum than a single stage pump. So also will a diffusion pump pull a deeper vacuum than any of them.

Good points. What most people consider high vacuum isn't really. Cryogenic or turbomolecular pumps will work to achieve true HIGH vacuum as well. Achieving true high vacuum isn't cheap. Like you said, that isn't really necessary for HVAC work.