Vacuum pumps are part of 1 of the final processes in the repair process. After you’ve diagnosed and repaired any leaks or other issues in the system it is time to recharge. Before recharging you want to make sure the system is free of any unwanted gasses, air, or water. If these were to remain in the system, it would turn the oil it runs on into sludge and leave 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 work on. Take the square root of that number and you’ll get the approximate CFM you need to have to work with that system. Typical residential systems need 4-5 CFM, while commercial and rooftop systems generally need as much as 6-8 CFM.