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Old 06-16-2014, 07:15 AM   #18 (permalink)
CapriRacer
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Quote:
Originally Posted by oil pan 4 View Post
Its looking like with the 50/50 CO2/R-404a mixture I am getting almost a 1psi change for every 10F in temperature change.

I did a test like this on tires if purged and filled my self with 95% nitrogen back in 2006 and saw something like a 1.5 psi change for every 20F change.

So the CO2/R-404a mixture only changes pressure with temperature slightly more than nitrogen. Nitrogen according to some people doesn't change pressure as it heats up.

http://ecomodder.com/forum/showthrea...tml#post255838
Yes, some folks believe that old wive's tale.

But I disagree about the gases behaving differently.

The Ideal Gas Law predicts a 12F change for every psi change, and 18F for 1 1/2 psi. Looks like good correlation there for the data you are getting regardless of the gas. (Keeping in mind you are only able to measure the pressure to 1/2 a psi.)
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