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Co2 vs n2 costs?

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  • Co2 vs n2 costs?

    So trying to figure out the economics of using n2 vs co2 for pushing beer from ferms to brites, and possibly using n2 for rousing hops.

    But they seemed to be quoted in lbs for co2 and cuft for n2. Anybody able to show me the conversion steps?

    And in a specific example- Our beverage folks quote co2 at $45 for 20#, and $61 for 50#. However they also quote the n2 in 20 and 50# tanks. Which is odd, no? Its $57 and $100.

    We’re in the process of getting a bulk 750# tank for co2, but the people’s republic of San Francisco is making us do all kinds of ridiculous drawings and permit BS so eventually those will come down alot.

    But we also want to use n2 for the hop rousing to limit aroma blowoff, etc. So need to know how to crunch these numbers.
    Last edited by brain medicine; 01-24-2020, 04:03 PM.

  • #2
    Wow! I can't believe how expensive those CO2 fills are. Since we're in a remote area, I have two 750# tanks and it costs us $0.30/lb. to fill them. Our 20# cylinders are around $20.00 to fill/exchange. We don't use many since everything is run off the big tanks except one kegerator.

    Don't know why they're quoting the nitrogen by lbs. instead of cu.ft. but here's the normal-sized bottles of nitrogen and their capacities:

    Size Capacity (cu.ft.)
    1 300
    2 200
    3 125
    4 80
    5 40
    6 20

    1# of CO2 contains 8.741 cu.ft., so a 20# tanks holds 175cu.ft.



    • #3
      yeah, this is from the soda company, its delivered. most bars/restaurants dont bother to check. but i will say that in SF even airgas/praxair/etc are all pretty damn expensive. its crazy. cant wait for our bulk unit to be put into service, but i literally just tore the draftsman a new Ahole for sending me plans that were total horseshit and lacked 2/3 of the edits i made for him on paper. good god. guess its gonna be a bit longer before that's sorted.

      but yeah, now i can do the math with praxair/airgas as they quote normally in cu ft.

      but i cant figure out what these soda guys are selling in "20#" tank of nitrogen. what's a pound of nitrogen? seems like there's a lot of variables to figuring that one out.


      • #4

        It's very easy to convert pounds to cubic feet. Ideal gas law: PV=nRT. And remember that 1 mole occupies 22.4 SCF. Or Google! Which tells me that 1 pound of nitrogen is 13.8 SCF.
        Phillip Kelm--Palau Brewing Company Manager--


        • #5
          the point is that nitro isnt sold by weight typically. So i googling 20# nitro tank doesnt work. Cuz theyre sold by cu ft. So if the numbers dont match then they’re either misquoting or doing something weird like using co2 tanks, which seems odd. According to you 100# of nitro is then 1380cu ft of gas. But look at dons post, that doesn’t match a typical nitro tank size.

          The more you look at it the less sense these guys are making on their quotes. At this point i think i just need to see their two tank sizes and figure it out myself.


          • #6
            I messed that up!

            Been working in godawful English units lately, so my memory did not serve me correctly. One mole (28g) of nitrogen is 22.4 LITERS. Not SCF! So one pound of nitrogen would be 363 liters. Or 12.9 cubic feet, which is substantively in line with 13.8. 100 pounds of nitrogen does indeed equate to around 1,380SCF. Obviously I can't speak to what your vendor sells. Perhaps they are using a standard 20 pound CO2 tank to put nitrogen in? The two gases differ significantly as not only are the molecular weights different, but nitrogen is sold as gas unless refrigerated. CO2 is liquid at moderate pressures & ambient temperature. If this is the case, a 20 pound CO2 tank filled with nitrogen would have much less weight than the 20 pounds of CO2 you could put in there at the same pressure. And they would not be selling you 20 pounds of nitrogen, but a "20 pound" tank full of nitrogen. Sort of how 16 penny nails are sold by the pound and don't cost 16 pennies each. In any case, your only recourse seems to be to talk to your gas supplier and ask what's up. Best of luck!
            Phillip Kelm--Palau Brewing Company Manager--