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## 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

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3. That is awesome. I always thought it didn't matter much until you really crank the pressure up. Great resource!

4. Nice link. That was the one neat thing about the Testo 550, temperature compensated pressure testing.

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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. 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.

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Thanks Much, y7turbo for sending me in the right direction,Kimosobee

8. Originally Posted by DDC_Dan
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 &deg;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.

9. 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/

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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. 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.

12. Originally Posted by waltervan
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.

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Originally Posted by garyed
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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