Nitrogen Versus Beer Gas

[hellsreach]

I'm designing my Keezer with 2 CO2 tap and 2 Nitro Taps. The 2 nitro taps were intended for a Chocolate Milk Stout that I try to always have on hand, and a cold brew coffee. My assumption was, for the Stout, I would carb it up with CO2 to a low level (in the neighborhood of 1 vol of CO2), and use the pure nitrogen to push it out. But, others are talking about beergas (60% CO2, 40% N2), but I didn't want to do that because that would alter the flavor of my coffee, yes?

What am I doing? Can you just carb with CO2 and discharge with N2 or do I need beer gas?

 

[Diver_Alan]

I would not expect this to work well. You would have CO2 in your beer and pure nitrogen in the headspace of the keg to push the beer. The Co2 in the beer would come out of solution until the pressure of the Co2 in the beer and in the headspace in the keg were equal. On a full keg with little headspace it might not be noticable. However as more beer was consumed and more nitrogen is added to the keg the Co2 level in the beer will keep dropping and the beer will become under carbonated. Beer Gas keeps this from happening because it has Co2 in it. This allows the Co2 in the beer to remain in the beer.
You could add more Co2 to the beer on a regular basis but not only would this be a PIA but the beer would taste different every few pours due to varying Co2 levels. Your best bet is to have 3 tanks, one each Co2, Beer Gas and N.

 

[PoppinCaps]

It works, but not for a long time. As Diver said, the CO2 will come out of solution due to partial pressures. But I don't keep my kegs hooked up to CO2 all the time, so relieving the pressure from time to time and recarbing (with a stone) isn't a big deal to me. Overnight carb, pressurize with N2, and you're back in business. I already had the N2 tank, so that's what I do.

 

[Supabrew]

Ah, I have the same dilemma! There is not room in my kegerator for more than 2 tanks

Do I:
1) use beer gas to push coffee and risk the CO2 negatively impacting the taste? or
2) use pure N2 to push beer and try to "juggle" gasses?

Negatives to #1, gathered from multiple forums:
-CO2 in beer gas gives coffee an acidic "bite"
-CO2 may contribute to cold brew coffee going stale prematurely
-restrictor plate may not knock all CO2 out of solution resulting in carbonated coffee

Negatives to #2, gathered from forums:
-fluctuating CO2 levels (decreasing every few pours)
-waste of gas due to venting
-pain in the ass

How would you even do #2? If I'm understanding it correctly, you would pressurize with straight CO2 to the target PSI (lower than normal for nitro), switch to straight N2 and pressurize, serve a few pints then disconnect N2, vent pressure in the keg, re-carbonate back to the target PSI and repeat the above?

 

[PoppinCaps]

It takes longer than you would think to degas the CO2 in the keg, and its so low in a nitro beer, it's hard to really detect a small difference. I think I purge and recarb about every 1.5gal or so. Have to keep the N2 charged up as you pour, but it's pretty hands off.