Vacuum pumps are part of among the final processes in the repair process. After you’ve diagnosed and repaired any leaks or additional issues in the machine it is time to recharge. Before recharging you need to make sure the 
system is free from any unwanted gasses, air, or drinking water. If we were holding to remain in the machine, it would turn the essential oil it runs on into sludge and keep behind damaging impurities.
The draw on a vacuum pump is usually broken down into its “CFM,” or Cubic Feet per Minute. To estimate what your CFM needs, look at the tonnage of the systems you focus on. Take the square root of that amount and you’ll obtain the approximate CFM you must have to work with that system. Typical Ac Vacuum Pump residential systems need 4-5 CFM, while commercial and rooftop systems generally require just as much as 6-8 CFM.