Is Nitrogen Really Cheaper

I was working on a refrigeration system recently, and between silver brazing and purging we used up 2 plus small bottles of nitrogen. Still
had some silver brazing to do and I just didn't want to run back to the store for a refill again. Its only $10 (plus some fee or other, plus hazmat) for still less than $20, but its a pain. I did a little research and I couldn't find any reason not to use Argon, and I have a tall bottle of Argon. Using the same flow rate from the argon bottle the high pressure needle has barely moved. Sure it cost a lot more to fill that tall bottle with more expensive gas, but I can still take it back in the shop and weld all day with it (depending on what I am doing).
All the nitrogen/argon does is purge the system and prevent oxidation inside the copper lines when silver brazing. Either way still have to pull 500 microns or better before calling my refrigeration guy to refill the system.
Hazmat for relatively low pressure nitrogen? really?
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On 7/1/2020 7:42 PM, Bob La Londe wrote:






You are indeed getting ripped off! I looked at a bunch of invoices from last year for medical grade nitrogen in tanks from NORCO. Never a mention of HASMAT charges.
We used the nitrogen in the selective soldering machine. NORCO delivered the new tanks and picked up the old ones. There was only a delivery charge.
Paul
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On 02/07/2020 03:42, Bob La Londe wrote:





When you say silver brazing what are you using out of curiosity, in the UK for copper to copper HVAC work silphos rod is used which doesn't require flux for copper to copper. Comes in various alloys and one local welding guy sells it by the stick to HVAC guys as they need very little
expensive.
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On 7/2/2020 4:17 PM, David Billington wrote:






Silphos. 15/5/80. Yes self fluxing. Does not prevent oxidation on the inside of the lines from heat. Inert gas is needed for that.
Sometimes the difference between "brazing" and soldering is defined as at above or below a certain temperature threshold. Silphos silver brazing is right at that threshold.
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wrote:

Allentown, PA. USA. All the welding joints around here tack on a hazmat fee and a doc fee. Totally BS.
Get a large N2 tank, probably cost you $15 to fill it.
Your high price is because it's a small tank, always a premium to fill those.
Maybe look into a medium size tank, the 300's are a pain to move around.
Randy Remove 333 to reply. Randy
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