How to Make a Leak-free Flare Fitting (Video)

With the growth in popularity of the ductless mini-split and VRF market, we are using more flare fittings, which can create several challenges:

  • They are difficult to make
  • Flair fittings, unless made properly, are highly susceptible to leaking

Here are some keys to making a proper flare fitting, to ensure a leak-free installation:

  • Use a good quality tube cutter
    • If it starts threading the pipe, it’s time to get a new one
  • Use a deburring tool
    • The ridge from gutting will be at the edge of your flare
  • Use the proper flaring block
    • Make sure it has an orbiting head and a clutch designed for R410A
  • Use a flare gauge
    • This ensures the flare is the correct size
    • Always use the flare nut shipped with the unit
  • Use a torque wrench
    • Be careful: over-tightening is one of the main causes for leaking flare nuts          
    • Never use pipe dope or thread sealant!

Keys to proper leak testing:

  • Pressurize to 500 PSI, as a mechanical fitting may not leak at 100 Psi
  • Let the pressure hold over night if possible
  • Always perform a triple evacuation
  • Use a Micron Gauge. Connect the micron gauge directly to the system not your pump or manifold
  • Draw vacuum down to 500 microns or below, and then let the vacuum hold for an hour

Contact the experts at B-Y with any questions!