100% nitro for serving?

[odie]

So, I was at a brewery I frequent and was talking with the owner/brewer about his nitro set up.

He says he is serving his nitro beers on 100% nitrogen. Not 70/30 or 80/20 beer gas. I had to ask several times cause I thought it might just be "terminology" differences between us as to his system.

He carbs the beers normally on CO2, to a low volume of CO2. And then to serve he just switches to 100% nitrogen to dispense the keg, not blended gas. A bottle of liquid gas lasts a long time, while a bottle of compressed "vapor" not so long.

I thought you had to serve it with a blend?

 

[mac_1103]

I don't believe that you actually have to serve with a blend but beer will lose carbonation if kept on pure nitrogen for a long time. Using beer gas at the correct pressure (and with the correct line length) can solve that problem, but so can adding some CO2 once in a while. And of course you can avoid the issue by serving the whole keg before it has time to lose enough CO2 to matter. Maybe they just have a really high turnover?

 

[odie]

That's kinda what I thought. Supposedly nitro will not dissolve into the beer. As the volume in the keg drops and head space is filled with only nitrogen, the co2 will bleed out until co2 in the beer and headspace is equal again. The beer gas replaces the CO2 that is dispensed with the beer.

I drink only a couple/few nitro pours a month it seems...so a long time on tap. A bar probably goes thru a keg in a matter of days, especially if it's a popular selection.

I guess what is the point at which it makes better sense one way or another? Adding CO2 every so often means even higher PSI to get it in the keg or you have to vent off (discard) the nitrogen to get pressure down to accept some CO2 and then hit it with nitro again...never ending cycle.

 

[mac_1103]

I guess what is the point at which it makes better sense one way or another?

@doug293cz probably has a spreadsheet for that...

 

[DuncB]

Nitrogen will dissolve in beer but it's in the region many hundreds of time less soluble than CO2 or Oxygen, depending on temp and pressure of course.

If it couldn't dissolve " the bends " wouldn't be a problem for divers rapidly decompressing.

 

[doug293cz]

Supposedly nitro will not dissolve into the beer.

N2 will dissolve in beer, but the solubility is about 100X lower than the solubility of CO2, so instead of grams/liter of dissolved gas that you can get with CO2, you only get 10's of milligrams/liter.

Because of the lower solubility of N2 in beer, smaller bubbles will be stable, which is the origin of the nitro effect of very tiny bubbles.

Brew on

 

[ITV]

Another possibility is that the brewery has a gas blender.

 

[DuncB]

also the diffusion gradient is less for nitrogen dissolved in beer.

 

[AlexKay]

I guess what is the point at which it makes better sense one way or another? Adding CO2 every so often means even higher PSI to get it in the keg or you have to vent off (discard) the nitrogen to get pressure down to accept some CO2 and then hit it with nitro again...never ending cycle.

This is interesting.

As far as carbonation of the beer is concerned, there's no difference between 10 psi CO2 in the headspace and a mixed headspace with 50 psi of N2 and 10 psi CO2. Also, both require the same amount of CO2 to be added to the keg. So there's no reason to vent off that 50 psi of N2, as you can just supply the CO2 at 60 psi. You'll end up with more CO2 filling up your supply lines, but as long as they don't leak, you'll use that CO2 eventually.

Maybe mixing time would cause a problem? Gases generally mix pretty quickly, but a motionless keg sitting cold in a freezer is pretty much the slowest mixing scenario. The back of my envelope says minutes to hours, depending on just how much headspace there is. But reaching equilibrium between dissolved gases and the headspace takes at least this much time, so it's hard to see how this causes a problem.

But the "adding every so often" part seems like a huge pain. You could automate this with a pressure gauge on the keg and solenoid valves, at which point ... you've built yourself a gas mixer.

 

[OLBrews]

I routinely do this at home: get the keg properly carbonated with CO2 then put on 100% Nitrogen for serving via a stout tap. Haven't noted a loss of carbonation while the beer is on tap, but the stout tap is knocking a good chuck of it out anyhow. This setup allows me to dual use the nitrogen for serving cold brew coffee which would get wrecked with a 70/30 gas blend.

 

[Closet Fermenter]

I routinely do this at home: get the keg properly carbonated with CO2 then put on 100% Nitrogen for serving via a stout tap. Haven't noted a loss of carbonation while the beer is on tap, but the stout tap is knocking a good chuck of it out anyhow. This setup allows me to dual use the nitrogen for serving cold brew coffee which would get wrecked with a 70/30 gas blend.

Interesting. I might have to give this a try. It would be nice to not have to deal with 3 kinds of bottled gases: CO₂, straight N, and beer gas. I use the straight nitrogen to push wine out of kegs, the beer gas for stouts, and CO₂ for everything else.

 

[odie]

Another possibility is that the brewery has a gas blender.

I don't think he has one. I thought he did when we previously talked a while back. But was chatting again this weekend and was in the back cold room with him...he didn't indicate or show me one. But that would explain the pure nitro bottle he had. But then again, he said he was using straight nitro to serve after the initial CO2 carb to a minimal volume or CO2.

 

[DuncB]

@AlexKay

If the headspace has Nitrogen gas in at 50psi and then you serve a pint of beer then top up with CO2 at 50 psi how do you know what ratio of Nitrogen to CO2 you have?

This is a complicated calculation and I think would vary as headspace increases and the constantly changing CO2 partial pressure.

Much more a calculation for @doug293cz to ponder with his calculator. I'd be interested in the projections. Possible that a topup regime could be worked out.

 

[AlexKay]

@AlexKay

If the headspace has Nitrogen gas in at 50psi and then you serve a pint of beer then top up with CO2 at 50 psi how do you know what ratio of Nitrogen to CO2 you have?

This is a complicated calculation and I think would vary as headspace increases and the constantly changing CO2 partial pressure.

Much more a calculation for @doug293cz to ponder with his calculator. I'd be interested in the projections. Possible that a topup regime could be worked out.

Nope, you’ve flagged the main problem.

I was envisioning a solution where you monitor the pressure, and whenever it drops to — whatever — 48 psi, you top it up with one of the 50 psi supplies. Automate this and do 5 N2 top-offs for every 1 CO2 top-off, and you should keep the ratios close enough. And that’s a gas mixer, albeit a kind of wonky digital one.

 

[DuncB]

I'm not sure that it's that simple!

 

[Closet Fermenter]

I'm not sure that it's that simple!

Right. Once it starts getting this complicated, it’s easier just to hook up a tank of beer gas. Heck, you don’t even have to have a nitrogen connection for your regulator!

 

[Halfakneecap]

So, I was at a brewery I frequent and was talking with the owner/brewer about his nitro set up.

He says he is serving his nitro beers on 100% nitrogen. Not 70/30 or 80/20 beer gas. I had to ask several times cause I thought it might just be "terminology" differences between us as to his system.

He carbs the beers normally on CO2, to a low volume of CO2. And then to serve he just switches to 100% nitrogen to dispense the keg, not blended gas. A bottle of liquid gas lasts a long time, while a bottle of compressed "vapor" not so long.

I thought you had to serve it with a blend?

I do this. Because renting a decent sized nitro mix bottle is ridiculous ( Australia ) . It'd last me forever.

I carb ( lightly ) with C02. Then use small kegland disposable Nitrogen bottles and a stout tap.

It works, but can be finnicky to get right ( the initial carb/Nitro serving pressure ratio ). I fluked it the first time and like a fool, didn't write it down. Next few times i had to adjust a little but it was worth it

After drinking, you need to bleed keg, and re attach C02.

Nitro bitter or mild or stout is pretty cool though. I do it a few times a year.

I literally just pitched a mild yesterday, and will be doing this for it. I will keep notes this time

 

[odie]

Right. Once it starts getting this complicated, it’s easier just to hook up a tank of beer gas. Heck, you don’t even have to have a nitrogen connection for your regulator!

really? my beer gas comes in CGA-580 bottles. CO2 regs are CGA-320.

 

[odie]

I think next bottle I will try pure nitro. Just with a totally flat keg to start...ie 1.0 volumes of CO2.

Should that flat keg be room temp or already cold crashed? Well, I guess at room temp it would actually have a wee bit of pressure per the carb charts.

I think I started the current kegs at 1.2 or there abouts...certainly not over 1.5

 

[odie]

https://www.northernbrewer.com/blogs/kegging-bottling-techniques/nitro-beer-101

 

[Closet Fermenter]

really? my beer gas comes in CGA-580 bottles. CO2 regs are CGA-320.

Whoops! My bad; you’re correct. The regulators that I use for straight nitrogen (pushing wine), also work for beer gas.
Typing with my brain out a gear; again!

 

[odie]

really the same regulator...just different valve fittings. they can be swapped.

 

[Closet Fermenter]

really the same regulator...just different valve fittings. they can be swapped.

Yeah, I think that’s where I goofed. I bought a bunch of brewing stuff from a guy cheap once, and included was a spooky looking beer gas regulator. I took the stem off and trashed the rest. When I got my first bottle of beer gas, I swapped out the stem and connector on my spare CO₂ regulator. So, when I look in my kegerator, I see my old CO₂ regulator. Again, jumped in the conversation before putting my brain in gear.

 

[DuncB]

I do this. Because renting a decent sized nitro mix bottle is ridiculous ( Australia ) . It'd last me forever.

Agreed beer gas even more expensive in NZ.
Hence I bit the bullet and got a micro nitro infuser, this puts air in the beer at the point of serving, you just carb the keg to about 1.2 vols with CO2 and replace that CO2 when it gets used, I use a low pressure regulator ( propane ) or a cask breather for this.

Another option is keep your eyes peeled for a beer engine, get a stout extension if you have a short spout and a stout creamer and you also get a wonderful pint of stout/mild.

 

[Halfakneecap]

Agreed beer gas even more expensive in NZ.
Hence I bit the bullet and got a micro nitro infuser, this puts air in the beer at the point of serving, you just carb the keg to about 1.2 vols with CO2 and replace that CO2 when it gets used, I use a low pressure regulator ( propane ) or a cask breather for this.

Another option is keep your eyes peeled for a beer engine, get a stout extension if you have a short spout and a stout creamer and you also get a wonderful pint of stout/mild.

I'd much rather have a beer engine but damn, they're expensive here haha

 

[DuncB]

I'd much rather have a beer engine but damn, they're expensive here haha

Mate in Brisbane picked one up for 150 dollars which seemed a very good price. Keep your eyes peeled on ebay and facebook

 

[VikeMan]

I routinely do this at home: get the keg properly carbonated with CO2 then put on 100% Nitrogen for serving via a stout tap. Haven't noted a loss of carbonation while the beer is on tap, but the stout tap is knocking a good chuck of it out anyhow.

You're definitely losing carbonation as the keg empties. And that last pint is going to have only a tiny amount of CO2 in it. But I suppose the nitrogen liveliness sort of masks that. If there's really no detectable (subjective) difference, there might be no reason to carbonate in the first place

 

[Halfakneecap]

You're definitely losing carbonation as the keg empties. And that last pint is going to have only a tiny amount of CO2 in it. But I suppose the nitrogen liveliness sort of masks that. If there's really no detectable (subjective) difference, there might be no reason to carbonate in the first place

This is why i put the C02 back on between drinking sessions ( after bleeding the higher pressure nitrogen from the keg )

But, i have forgotten before and while it did lose carbonation, for stout or mild i honestly didn't mind at all