Hallo folks, I'v just started a course in ref engineering about 4 weeks ago. I was just wondering if you can figure out how much refrigerant you need to recharge a system (any system) by the pressure, temperature relation?

I only ask because some of the system I'v been working on dont say and have only done two weeks of my course so far and although they touched on this area I cant find it in my notes (must keep better notes)