Vacuum pumps are part of one of the final processes in the repair process. After you’ve diagnosed and repaired any leaks or various other issues in the system it is time to recharge. Before recharging you desire to make sure the machine is free from any unwanted gasses, air, or water. If these were to stay 
in the system, it would turn the essential oil it operates on into sludge and leave behind damaging impurities.
The draw on vacuum pressure 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 work on. Take the Ac Vacuum Pump china square root of that number and you’ll obtain the approximate CFM you must have to work with that system. Typical home systems need 4-5 CFM, while industrial and rooftop systems generally need just as much as 6-8 CFM.