Are you sure your nitrogen braze purge is clean? Look at this...
Soda fountain CO has less H2O than some of these classifications.
Which one does your supplier sell you?
The suppliers I called did not know the purity of their own Nitro.
Called a national chain gas supplier an HE said they sold all industrial grade to HVAC houses in MI.
You guys might as well switch over to industrial CO2 if that is the case. It's drier.
So industrial Grade has roughly 16 ppm water vapor in it, while the atmosphere on average has 2500 ppm, And With oxygen the nitrogen bottle has 10 ppm while the atmosphere has on average 209,460 ppm. That 16ppm and 10ppm hasn't caused any known problems that I'm aware of, While industrial grade CO2 has average 32ppm water vapor...http://www.abbottwelding.com/index.p...urity%20Levels I'd Stick with Nitrogen and a Deep Vac considering CO2 has twice the water vapor according to abbott.
Looks to me like we are splitting hairs...
Originally Posted by Greend88
Reducing water vapor by 99.36% and reducing O2 by 99.9948%... well that is close enough for work outside a chemistry lab (Used to do maintenance for a chemistry lab... know how procedures are done there).
Anyone know of any test results where less than 1% of water vapor or less than 1/100 of 1% of O2 would make a difference? Be interesting if anyone has even run that test...
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The h2o content is emphasized because we use gas to sweep the system between evacs and blow out impurities. The less h2o the better.
Originally Posted by ga-hvac-tech
That is not the table I was getting my info on Co2.
Seems the purity levels vary by mfg. The Airgas table we have shows 15ppm for their CO2 welding gas.
Airgas shows their bone dry co2 as a Cat IV while Abbott calls it a Cat III.
So what does your purity sheet show for Nitrogen from airgas?
Daikin says to use "dry nitrogen". When I asked the supply house guys if the nitrogen was "dry", I got a blank stare and they said "huh?".
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Don't use nitro. I looked for it but could not find it on Air gas. But even if THEY have a grade that is close to what I posted you are still more cost effective using co2.
I raised this question cause there seems to be no firm consensus on what we call "dry". So my point is with so many grades of co2 dryness that don't seem to agree, how do we know what we are getting ?
Edit: Meant to say nitro not co2 dryness.
Originally Posted by hvac5646
Id say use whatever your comfortable with. When it comes down to it we just want something that will prevent copper oxide from forming. whatever inert gas that works and is cost effective you can use. A small ppm of oxygen isnt gonna be enough to cause any problems nor is the few ppm moisture content. your vaccum pump will remove all that and the dryer will catch any thats left.
I use nitro, its what the co. buys me to use. What's the big deal? Use whatever you like.....
Originally Posted by chuckcrj
For you and and other guys who use co supplied nitro it's a moot point.
But those of us who are responsible for our own materials, CO.2 is the better bet cause you get approximately 3 to 4 x the amount of gas in the (close to ) same size tank than you would with nitro. And Co2 cost less.
A lot of friends, and posters here, have complained about running out of nitrogen
on a busy day or a big job. Which would you rather carry?
The MBK 6 using a flow meter runs out of gas when brazing up a four ton evap and line set with a flow rate of 5 sftf.