Page 1 of 3 123 LastLast
Results 1 to 13 of 30
  1. #1
    Join Date
    Jan 2010
    Location
    Vermont
    Posts
    15

    Any harm with cutting nitro flow?

    I've some trouble trying to trickle nitrogen through my last brazing joints without some sort of pin hole, I've always killed the nitrogen on my very last, but is it possible I'm trapping oxygen inside the unit by doing so?

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,758
    If the lines have been under a constant nitrogen purge, there is almost zero chance of nitrogen getting in the system of you cut the purge.


    I'd suggest cutting the pressure down, first.

  3. #3
    Join Date
    May 2012
    Location
    Upper Michigan
    Posts
    3,589
    I don't know I'f this is technically correct but I use soap bubbles on the outlet of the nitrogen and just get it bubbling a little.

  4. #4
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,596
    Are you using a flow meter or just the regulator to control flow?

  5. #5
    Join Date
    Jan 2010
    Location
    Vancouver Island
    Posts
    375
    Get a flowmeter...only around $40 dollars. Makes it so much easier to control.

  6. #6
    Join Date
    Aug 2012
    Posts
    68
    Looks like the flowmeter is on sale at Johnston for $23. Great price!

  7. #7
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,596
    Quote Originally Posted by georgehvac View Post
    Looks like the flowmeter is on sale at Johnston for $23. Great price!
    Money well spent IMO.

  8. #8
    Join Date
    Jan 2010
    Location
    Vermont
    Posts
    15
    I had a used one, the glass cracked because a co-worker dropped it! Hah, anyway I've tried to just crack the port just a bit. I will invest in a new one and try at it again. I also want to sign up for a brazing class, or at least find a bunch of scrap to practice on... thanks guys

  9. #9
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    I usually flow nitro, with flow meter from discharge to suction and leave suction open for nitro to escape. Prevents positive pressure from building and pushes air out so only nitro in system. Blow it hard for 1-2 minutes to purge then cut flow back to a trickle. Need magnet ring on solenoid valve, if present, but it works pretty good.

  10. #10
    Join Date
    Jan 2013
    Location
    New Jersey
    Posts
    33
    Actually this brings up an old question for me. What is the best method for brazing a hermetic compressor, being you can't get a flow through it?

    I've just purged each side with nitro for a few seconds to get as much air out as I could. Haven't had any issues, don't know if anyone else has a better method?

  11. #11
    Join Date
    Jan 2010
    Location
    Vermont
    Posts
    15
    Bought a new flow meter! I hope I have better luck.

    Quote Originally Posted by SEIDexter View Post
    Actually this brings up an old question for me. What is the best method for brazing a hermetic compressor, being you can't get a flow through it?

    I've just purged each side with nitro for a few seconds to get as much air out as I could. Haven't had any issues, don't know if anyone else has a better method?
    I know this is off from original topic but....

    I cut my piping rather than unbrazing them to avoid burning oil when taking the old one out. Unless you want to burn a few holes in your lungs, I don't recommend breathing it in, haha. I like to have nitro flowing for a compressor to keep it cool when brazing with oxy seems to work for me.

  12. #12
    Join Date
    Dec 2012
    Location
    columbus, OH
    Posts
    2,071
    Ive been taught run atleast 3psi of nitro in opposite direction of refrigerant flow when brazing.

  13. #13
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,425
    I got tired of breaking flow regulators, so I made up a more bullet-proof type:


    It's just a scrap piece of 7/8" ACR with end caps, a couple of 1/4" male flare connections and about 10 ft of .042" capillary tube coiled up inside. I guessed at the cap tube size, but with the nitrogen regulator set at 30 psig it delivers a perfect purge flow.

Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event