Hello folks, I have two simple questions and some ideas about it: 1. Why is it harder to create a vacuum and takes more time to evacuate the chamber when the air inside is humid? Humid air is lighter than dry air. So I have no idea why it takes longer... 2. Why do you use nitrogen to vent the chamber? Is it because nitrogen is lighter than air and so at the same gas density you have more particles of a light gas than of a heavy one and because the pressure only depends on the particle noumber density (same temperature)? So I reach the pressure compensation with nitrogen faster and I use less mass. When I evacuate my chamber I have a lighter mass inside it and the amount of time to evacuate is shorter because my pump has to work less? I really appreciate any help and explanations. Feel free to mention details if you like! :) Thanks in advance guys!!!