I donít always use torches in the kitchen but when I do...
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  1. #1
    Join Date
    May 2015
    Location
    Barre Town, VT
    Posts
    847

    I donít always use torches in the kitchen but when I do...

    I can check ďuse oxy-acetylene torch in kitchenĒ off my bucket list. The compressor in my 16yo fridge died last week so I decided to replace it. Iím not a professional refrigeration repairman but Iíve done enough of it to pick up a couple tips on brazing copper refridgeration lines.

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    First this isnít soldering like water piping, this is brazing with SilFos rods. To make a gas tight copper to copper joint the first is to use a swaging tool to create a bell end on one tube that will slide over the other tube. SilFos rods donít require any flux because the phosphorus in the rod acts as the flux.

    Be careful not use an oxidizing flame because it will burn right through the copper tubing. I use a slightly carburizing flame for the brazing. Iíve found a #00 tip works well on 1/4Ē and under lines that are found in refrigerators, dehumidifiers and window AC units. Iíve never worked on a whole house AC with big lines so I donít know what size tip it would take.

    The carburizing flame will keep the tube from oxidizing on the outside but the oxygen in the open system will oxidize the inside of the tube. This is bad as it can flake off and plug up the tiny capilary tube or get sucked into the compressor. Because of this the lines need to be purged with sheilding gas, just like tig welding stainless pipe. With tig welding stainless argon is usually used but for refrigerent work everybody seems to use nirtogen because it is cheap. Back when I repaired a crack in my dehumidifier I didnít have any nirtogen so I used argon and it worked fine.

    I hope this helps someone, even if you never plan on playing with refrigeration systems copper to copper brazing is an interesting skill to have and lets you practice heat control with the torch.
    My "collection":

    Homemade Stick Welder
    Victor O/A Torch
    AC 225
    Ideal Arc 250

    HF 90 Amp Flux Core
    HF Mig 170
    Solar 2020 Plasma Cutter
    Power i-Mig 140E
    Harris O/A torch
    HF Dual Mig 131
    140ST
    Alpha Tig 200x

  2. #2
    Join Date
    May 2018
    Location
    Land of the Toxic Avenger
    Posts
    695

    Re: I donít always use torches in the kitchen but when I do...

    I agree with your evaluation of it's "not a normal job", as it took 4.... YES I SAID 4 technicians to fix my freezer because the first guy came out and brazed the new condenser in the freezer section, and in doing so, floated a chunker down the tube and blocked the condenser from functioning fully.

    The only way they knew this was to completely disassemble the original (First) technicians work, in which the clogged copper tubing was found. Too much solder, and not enough skill level, I guess.
    T man.


    15 + years working for myself, and by golly, I still don't know what I want to do when I grow up.

  3. #3
    Join Date
    Dec 2014
    Location
    Northern California
    Posts
    115

    Re: I donít always use torches in the kitchen but when I do...

    Those socks are not the proper attire. OSHA says they should be black for proper welding...and no holes...

  4. #4
    Join Date
    Mar 2017
    Location
    bar stool
    Posts
    1,099

    Re: I donít always use torches in the kitchen but when I do...

    Nitrrogen purging is to prevent scale creation inside the tube.
    Nitrogen also absorbs water in the tube system to make it go away in the vacuum purge.

  5. #5
    Join Date
    May 2015
    Location
    Barre Town, VT
    Posts
    847

    Re: I donít always use torches in the kitchen but when I do...

    Quote Originally Posted by Tarmstrong View Post
    Those socks are not the proper attire. OSHA says they should be black for proper welding...and no holes...
    You’re right, I’ve since tagged out those socks as defective equipment because of the holes. Safety first.

    Quote Originally Posted by Virgil5 View Post
    Nitrrogen purging is to prevent scale creation inside the tube.
    Nitrogen also absorbs water in the tube system to make it go away in the vacuum purge.
    I never knew that about nitrogen absorbing water, but it makes sense since the big battle is trying to suck all the moisture out of the system before adding the refrigerent so any gas that helps carry it out would be the gas of choice.
    My "collection":

    Homemade Stick Welder
    Victor O/A Torch
    AC 225
    Ideal Arc 250

    HF 90 Amp Flux Core
    HF Mig 170
    Solar 2020 Plasma Cutter
    Power i-Mig 140E
    Harris O/A torch
    HF Dual Mig 131
    140ST
    Alpha Tig 200x

  6. #6
    Join Date
    Mar 2018
    Location
    Tampa, Florida
    Posts
    599

    Re: I donít always use torches in the kitchen but when I do...

    Quote Originally Posted by Tarmstrong View Post
    Those socks are not the proper attire. OSHA says they should be black for proper welding...and no holes...
    “Hooneyy? Why does one of your socks have a yellow sticky note on it that says NFG?”
    -Mark Smith

    Vulcan ProTig200
    Vulcan MigMax 215
    Hypertherm PowerMax45 Xp

  7. #7
    Join Date
    Oct 2006
    Location
    Illinois
    Posts
    8,262

    Re: I donít always use torches in the kitchen but when I do...

    Nothing wrong with replacing compressor. I would have replaced the entire refrigerator. The new ones have great insulation factors and efficiency. Your utility provided may even offer a rebate by upgrading . I got a $100.00 back and just bought the basic model. No fancy garbage, freezer freezes, and refrigerator keeps cold.

  8. #8
    Join Date
    Jul 2011
    Location
    Bossier Parish La.
    Posts
    5,283

    Re: I donít always use torches in the kitchen but when I do...

    Quote Originally Posted by Tarmstrong View Post
    Those socks are not the proper attire. OSHA says they should be black for proper welding...and no holes...
    Plus steel toed when worn without boots.

  9. #9
    Join Date
    Mar 2017
    Location
    bar stool
    Posts
    1,099

    Re: I donít always use torches in the kitchen but when I do...

    Quote Originally Posted by Iain P View Post


    I never knew that about nitrogen absorbing water, but it makes sense since the big battle is trying to suck all the moisture out of the system before adding the refrigerent so any gas that helps carry it out would be the gas of choice.
    There are 2 varietys of Nitrogen in cylinders.
    Oil Pumped and Water Pumped.
    It is indicated on the cylinder label.

    When you're just flowing nitrogen to prevent oxidation inside the tube it don't make much difference which you use. When you're dewatering a tube system Oil Pumped gives you a bit more benefit.

    Same applys when using Nitrogen to blow up tires on your personal jet aircraft.

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