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  1. #1
    Join Date
    Jan 2012
    Location
    Oregon
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    101

    Using nitrogen as a leak detector

    When you use nitrogen as a leak detector for a small commercial refrigeration system are you suppose to pressurize the system to 300 psi? And how do you tell if there is a leak? If it doesn't pressurize to 300?

  2. #2
    Join Date
    Nov 2006
    Location
    Southeastern Pa
    Posts
    18,593
    I use the Amprobe ultrasonic leak detector to find escaping nitrogen.
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    2 Tim 3:16-17

    RSES CMS, HVAC Electrical Specialist

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  3. #3
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,692
    300 pounds is crazy high. No need at all for pressures that high, IMO.

    I'll typically pressurize to 100 or so

    Use an electronic leak detector to find the leak

  4. #4
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    150 typically for me.

  5. #5
    Join Date
    Jul 2011
    Location
    Lehigh Valley, PA
    Posts
    448
    Do you have a nitrogen regulator which can pressure up to 300psi? Probably not. And if you pig tail it from the cylinder valve to the system you risk splitting an evaporator.
    I pressurize to 50psi. Sometimes I'll go to 80 if I suspect a leak and still not finding one.

  6. #6
    Join Date
    Jun 2009
    Location
    DFW, TX
    Posts
    673
    I equalize pressures with the existing refrigerant that's in the system and that typically gets me to about 50-75psi (depending on the refrigerant). If I can't find it with that, add nitrogen up to 200#. Leak check with electronic leak detector then always confirm with soap bubbles.

  7. #7
    Join Date
    Jan 2012
    Location
    Oregon
    Posts
    101
    Thanks for the input. I just used m electronic leak detector. It works great. I was just curious about using nitrogen as a leak detector.

  8. #8
    Join Date
    Sep 2012
    Location
    New York
    Posts
    174
    I was under the impression a leak test should be 150psi and hold for 15 minutes. You should always go with manufacture rating on the nameplate it will often state a design pressure/ and or a max test pressure. Agreed try and confirm with soap bubbles as trippintlo stated but hey sometimes the coils gotta go!

  9. #9
    Join Date
    Jul 2012
    Location
    Western KY
    Posts
    1,221
    If I have to us nitro, system flat, I'll start about 80-100psi. If still can't find it ill dump nitro and add a trace charge of refrigerant and push pressure up to 100psi with nitro then use ELD. I can count on one hand how many times in 20+ years this hasn't worked. If it doesn't ultra sonic is next then dye then BFH!!

  10. #10
    Join Date
    Feb 2009
    Posts
    134
    Pressure is limited by pressure rating of system, old R12 hermetics were rated at 150#

  11. #11
    Join Date
    May 2003
    Location
    Utah
    Posts
    733
    Here's an interesting presentation from FMI Energy a few years ago, discussing leak test methods with a mixture of Nitrogen and Hydrogen....I personally know the presenter, and he has had great results with this method.
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