Something I haven't seen discussed much is using N2 gas to reduce O2 ppms in fermentation vessels / dry hoppers, etc. I'm guessing we all center the thinking around CO2 because we already have CO2 tanks and regulators, and the beer itself is generating CO2. However, N2 is generally way cheaper than CO2. So why not use it for purging atmosphere from our fermenting beer? I imagine there's a bit of initial investment (slippery slope in this hobby), but long term it must pay off, no?

I'm curious how much it would cost to piece together an N2 purging system, say, for a unitank. I'd hate to waste CO2 to get the proper number of purge cycles. I'm planning to eventually make a hop dropper, but even that needs to be purged of atmosphere. I guess here's what you'd need:

• N2 tank: About $100USD for brand new empty tank
  
  • Not sure how much a fill costs for a 5# or 10# tank, hard to find online with my admittedly lazy googling so far
• N2 regulator (important: you can't use a CO2 regulator): Kegland has a ~$25USD part but not sure how easy it is to get in the US vs Aus, otherwise I'm seeing $117 (!!!!) for a traditional regulator with 5/16" barb
• A flow regulator would be preferred for the function of delivering a known amount of N2 gas to purge the vessel, not sure what's available out there
  

I wonder if anyone has a better idea of a full build list with costs. It might be easier to search for equipment that handles beermix, as it should be compatible with pure N2 gas as well. Also just wondering what general feedback folks would have for this approach.