Vacuuming procedure

Vacuuming procedure


Checking your equipment

  • On your gauge manifold inspect all seals, valves and connections and replace/repair as required
  • Remove all of the old oil from your Vacuum pump, flush through with fresh oil and then recharge the pump with vac pump oil
  • If necessary you can run the pump with the valve closed to warm the pump and oil up, drain and flush with fresh oil before again filling.
  • To check the operation of the vacuum pump fit a calibrated vacuum gauge to the inlet and achieve the lowest pressure possible. Isolate the pump and watch for any rise in pressure. This may indicate a faulty pump or connection.

Preparing the system for evacuation

  • Ensure the system being evacuated is not at a positive pressure and connect your vacuum pump to the system, preferably on both the low and high side of the system.
  • Fit a calibrated vacuum gauge to the system, as far away from the vacuum pump as possible.
  • Ensure that you have opened all valves on the system and that service valves mid seated.
  • Switch on the vacuum pump before opening the manifold valves.
  • Operate the pump with the gas ballast open until a reading is indicated on the vacuum gauge. Close the ballast and run until the required vacuum has been achieved.
  • Isolate the vacuum pump and record the pressure. A rise in pressure generally indicates a leak or that moisture is in the system.

Triple evacuation

  • If no rise is shown you can introduce O.F.N. into the system until it reaches just above atmospheric pressure, this will help to absorb any remaining moisture.
  • Repeat the process as above until a last (Third) vacuum has been achieved.
  • Isolate the vacuum pump and hold the vacuum for as long as you can to ensure that no moisture is in the system and the system is leak free
  • Log the vacuum achieved.
  • The system is ready to charge with refrigerant

For more info see

System evacuation part 1

System evacuation part 2