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Pure Nitrogen for Homebrew

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dogbull28

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Hello,

I frequently brew at home and up til now have simply used CO2 as my gas of choice. I have decided to try my hand at a Guinness Clone, but on top of that, I want to tackle doing Nitro Cold Brew coffee. My understanding is that for the coffee, I'll need pure Nitrogen (not mixed with CO2), but my question is regarding the Guinness - will I be able to use the same pure Nitrogen on the Guinness? I have purchased the Quick Cascade Nitro Coffee Keg Lid (Link at end of post) for both my coffee keg and my beer keg.

I bought all of the equipment assuming that this would work for both the coffee and beer, but am starting to question my decision. I'd rather have a 2 tank setup for this because that would require me buying a 2nd nitrogen regulator for the Beer Gas mixture.

Anyone with experience with this? Any downsides to using pure Nitrogen on a Guinness Clone other than under-saturation of gas?

Quick Cascade Nitro Coffee Keg Lid
 

Vale71

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Any downsides to using pure Nitrogen on a Guinness Clone other than under-saturation of gas?
The only downside is that unless you drink the whole keg in a single session the beer will become less and less carbonated with each pint you pull. Considering that the style has a very low carbonation to start with you'll end up with flat beer very quickly.
If you don't want to purchase a beer gas cylinder you'll need to purchase an inline gas blender. Unfortunately they tend to be quite expensive, so that purchasing beer gas is almost always the best solution.
 

bracconiere

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my coffee keg

Welcome! and, wait....a coffee keg? i honestly have never heard of a coffee keg before....is this like a 5 gallon corny full of coffee, pushed with nitro?

(soryy for answering a question with a question...just thinking my percolators pot is small, and maybe a 5 gallon keg of nitrogen foamy coffee in the morning would be 'different'?)
 

RM-MN

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CO2 dissolves into the beer. Nitrogen does not. If you want the advantages of nitro and carbonation you use beer gas or you buy a mixer. Otherwise you get flat beer.
 
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dogbull28

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Doesn't the diffusion stone help with getting Nitrogen into the beer? It increases the the overall gas to liquid surface area and should simulate shaking a keg. My understanding is that Nitrogen will still go into the beer it just takes longer.
 
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dogbull28

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Welcome! and, wait....a coffee keg? i honestly have never heard of a coffee keg before....is this like a 5 gallon corny full of coffee, pushed with nitro?

(soryy for answering a question with a question...just thinking my percolators pot is small, and maybe a 5 gallon keg of nitrogen foamy coffee in the morning would be 'different'?)
I just mean that I bought a smaller (2.5gal) corny keg.
 

Vale71

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Doesn't the diffusion stone help with getting Nitrogen into the beer? It increases the the overall gas to liquid surface area and should simulate shaking a keg. My understanding is that Nitrogen will still go into the beer it just takes longer.
I'm sorry but your understanding is wrong. Nitrogen has minimal solubility so you can only get a very tiny amount of it in solution, although it will certainly take a very short time to achieve saturation due to the amount being so small compared to the amount of CO2 you would have dissolved at the same pressure.
 
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dogbull28

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@Vale71 thanks for your input. I'm glad you're able to correct my misunderstanding. I suppose I'll have to figure out a way to add beer gas to my supply then.

Thanks for all of the help!
 

Bobby_M

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You can make it work although it's not ideal. You would carbonate your stout to about 1.5 volumes and then push it out under high pressure with nitro. After about a gallon of dispensing, you'd have to vent the nitro out of the headspace and pressurize with CO2 and that would have to happen occassionally so you'd spend up the nitro faster due to all the venting.
 

bracconiere

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hate to hijack...so the nitrogen dissolves in the co2 then? trying to figure out why the bubbles are smaller with beer gas....
 

Vale71

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just googled it for an answer...so the only point in using beer gas is for pushing at higher psi in a long draw system?
While mantaining low carbonation, yes. There is of course a small amount of N2 dissolved but that alone would not give any significant carbonation.
 

bracconiere

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While mantaining low carbonation, yes. There is of course a small amount of N2 dissolved but that alone would not give any significant carbonation.

i learned something! i always thought the nitrogen did something.....


(if i realize my dream of having beer taps at every seat in the house, and bed....i now know to use beer gas! ;))
 

Dan880

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I think there is a physics law of mixed gasses (I think Boyle’s) that states mixed gasses retain there individual properties and behave as if they are not mixed. That’s why if you’re putting up a stout under lower carbonation which would call for 4 psi of co2 and your beer gas is 75/25 the regulator would call for 16 psi to keep the right co2 level. The higher pressure in the keg is the cause of those tiny tasty bubbles. Hope it helps.
 

uprightfever

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The tiny bubbles are caused by the higher pressurized beer being forced through tiny holes in the stout faucet.
 

Jbuckley1996

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Actually the reason for the tinier bubbles is the nucleation and interfacial surface tension properties properties. Nitrogen nucleates easier and forms smaller bubbles. I know this from my days in polyurethane foam production.
 

Vale71

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Except the bubbles are mostly filled with CO2 and very little nitrogen at all. At 10°C nitrogen is about 100 times less soluble than CO2. Even using 75/25 gas mix which triples the partial pressure of N2 compared to CO2 thus effectively tripling the concentration of nitrogen you're still left with a ratio of 33:1, meaning there is actually very little N2 in each bubble.
 

Dan880

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I didn’t mean to sound like I was the physics expert know it all guy But what I guess I wasn’t clear about is that the nitro isn’t, for all intents and purposes, soluble and the increase in pressure is required in the same ratio as the beer gas mix to get the co2 into the beer. the higher pressure in the keg results in smaller bubbles of co2 In the beer.
 

Beholder

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I had a similar choice to make as I have nitro beer and coffee on tap. I considered two options, the first the have put nitro and burst CO2 into the nitro beer periodically (e.g. drop keg pressure and push back up to serving pressure every few days) to keep it approximately right and the second to serve the coffee off beer gas.

Since I didn’t want to hassle of chasing the nitro beer and it coming off tap differently over weeks and over/under carb headaches, I started with the latter option. While it’s not the purist clean nitro flavor, I have come to enjoy the light carb in the morning nitro coffee. You may want to try one way or the other and see how you like it. I always figured I could fill the tank with the other type of gas if I didn’t like it, but found I didn’t need to try the alternate!
 

Beholder

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I didn’t mean to sound like I was the physics expert know it all guy But what I guess I wasn’t clear about is that the nitro isn’t, for all intents and purposes, soluble and the increase in pressure is required in the same ratio as the beer gas mix to get the co2 into the beer. the higher pressure in the keg results in smaller bubbles of co2 In the beer.
It’s solubility is much lower than CO2, see page 30 of the link below for mole fraction of dissolved N2 at atmospheric pressure (760mmHg) in the first column versus high pressure (2280mmHg) which is the range for nitro serving pressure. You only see mole fraction increase 19e6 to 56e6.


The smaller bubbles are due to smaller amount of CO2 dissolved in the beer that results in lower partial pressure to force the gas out of solution. That combined with high serving pressure through a creamer faucet pushes the CO2 out of solution in the form of a cascade. You can get a similar mouth feel and taste (if not exactly the same effect) by under carving and pouring the beer several times across two glasses, though doesn’t quite compare to the beauty of a cascade.

Edit: Forgot to add link.
 
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