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  1. #1
    Join Date
    Feb 2010
    Location
    Howell, Michigan
    Posts
    143

    nitrogen calculater

    I have been looking for Marc O'Brians Nitrogen Calculater. I had it saved , i thought but I can't find it now. I'm hoping one of you can point me in the right direction. I need to use these calcs today. Thanks, Kimosobee

  2. #2
    Join Date
    Jul 2006
    Location
    Anytown USA
    Posts
    2,060

  3. #3
    Join Date
    Mar 2009
    Location
    Mid-Mo
    Posts
    3,595
    That is awesome. I always thought it didn't matter much until you really crank the pressure up. Great resource!

  4. #4
    Join Date
    Feb 2006
    Location
    FL
    Posts
    565
    Nice link. That was the one neat thing about the Testo 550, temperature compensated pressure testing.

  5. #5
    Join Date
    Feb 2013
    Location
    Phoenix, AZ
    Posts
    198
    Is anyone interested in the actual calcs to get the answer? Using this formula you could actually do the math on a calculator or smartphone (if you didn't have access to the online calc).

    Lets take start temp of 90F, end temp of 100F (I'm in Phoenix :-) ) and a start pressure of 200 psi:

    First, convert the temps from degrees F to Kelvin by adding 460 (0 Kelvin is absolute zero):

    90 + 460 = 550
    100 + 460 = 560

    Then divide the end temp by the begin temp (in Kelvins) to get the temp ratio:

    560 / 550 = 1.018

    Now convert gauge pressure to absolute by adding 14.7 psi (atmospheric pressure):

    200 + 14.7 = 214.7

    multiply the absolute pressure by the temp ratio:

    214.7 * 1.018 = 218.56 psi

    Of course tha answer is absolute pressure , so subtract 14.7 psi to get back to gauge pressure:

    218.56 - 14.7 = 203.86 psi

    Voila!

    Dan

  6. #6
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    I always just did the equation with a calculator, but I've bookmarked the calculator page on my phone now, thanks.

    Daikin teaches a simplified equation, but I never used it because it is less accurate than using the P1/T1 = P2/T2 equation.
    If more government is the answer, then it's a really stupid question.

  7. #7
    Join Date
    Feb 2010
    Location
    Howell, Michigan
    Posts
    143
    Thanks Much, y7turbo for sending me in the right direction,Kimosobee

  8. #8
    Join Date
    Jul 2009
    Location
    South Carolina
    Posts
    3,197
    Quote Originally Posted by DDC_Dan View Post
    Is anyone interested in the actual calcs to get the answer? Using this formula you could actually do the math on a calculator or smartphone (if you didn't have access to the online calc).

    Lets take start temp of 90F, end temp of 100F (I'm in Phoenix :-) ) and a start pressure of 200 psi:

    First, convert the temps from degrees F to Kelvin by adding 460 (0 Kelvin is absolute zero):

    90 + 460 = 550
    100 + 460 = 560

    Then divide the end temp by the begin temp (in Kelvins) to get the temp ratio:

    560 / 550 = 1.018

    Now convert gauge pressure to absolute by adding 14.7 psi (atmospheric pressure):

    200 + 14.7 = 214.7

    multiply the absolute pressure by the temp ratio:

    214.7 * 1.018 = 218.56 psi

    Of course tha answer is absolute pressure , so subtract 14.7 psi to get back to gauge pressure:

    218.56 - 14.7 = 203.86 psi

    Voila!

    Dan
    I got a similar formula doing some research online but it converts °F to celsius then adds 273.15 to get kelvin.
    So 90 F converts to 305.37 kelvin etc. but the answer ends up about the same for the pressures. I don't know which is more accurate but I would think converting to celsius is more precise than just adding 460.
    I just put up this calculator & you can see a very slight difference:
    http://www.oceanhvac.com/nitro.php
    If anyone knows which way is truly more accurate I'd sure like to know.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  9. #9
    Join Date
    Feb 2004
    Location
    Ky
    Posts
    269
    We're mixing our Rankines with our Kelvins here.
    Here's the neatest conversion tool I know of (if you don't have it already) http://joshmadison.com/convert-for-windows/
    LN

  10. #10
    Join Date
    Jun 2003
    Location
    Gulf Coast
    Posts
    174
    Could someone please elaborate on what a nitrogen calculator is, how to use it, when to use it, and why to use it.
    Thanks
    Walter

  11. #11
    Join Date
    Jun 2004
    Location
    Eugene, Oregon
    Posts
    1,018
    The Daikin class uses the formula: (TP-TC)x0.08=PD
    Temperature when system is pressurized minus temperature when system is checked, then multiply by 0.08 to get the pressure drop.
    "The bitterness of poor quality remains long after the sweetness of low price is forgotten". --Benjamin Franklin
    "Don't argue with an idiot, they will drag you down to their level and beat you with experience". --Mark Twain
    http://www.campbellmechanical.com

  12. #12
    Join Date
    Jul 2009
    Location
    South Carolina
    Posts
    3,197
    Quote Originally Posted by waltervan View Post
    Could someone please elaborate on what a nitrogen calculator is, how to use it, when to use it, and why to use it.
    Thanks
    Walter
    It just shows how much the temperature changes the pressure. Lets say you were leak testing a system & put in 350 psi of nitro over night. If it was 95* out when you pressurized it & it was 65* when you got back to check in the morning then it should be 330 psi. if there were no leaks. The pressure change is pretty minimal & I've never used a calculator for it but I figured I write one today since the question was asked.
    Gary
    -----------
    http://www.oceanhvac.com
    An engineer designs what he would never work on.
    A technician works on what he would never design.

  13. #13
    Join Date
    Jun 2003
    Location
    Gulf Coast
    Posts
    174
    Quote Originally Posted by garyed View Post
    It just shows how much the temperature changes the pressure. Lets say you were leak testing a system & put in 350 psi of nitro over night. If it was 95* out when you pressurized it & it was 65* when you got back to check in the morning then it should be 330 psi. if there were no leaks. The pressure change is pretty minimal & I've never used a calculator for it but I figured I write one today since the question was asked.
    Thanks

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