[Lednerg]

Hello,

I brewed a 9.5% RIS for my first nitro beer.  Hoping someone can help me troubleshoot my lack of a sweet foamy nitro pour.

I have a 75/25 beer gas mix, nitro regulator, and stout faucet.

I have had my keg hooked up to the nitro blend for over 3 weeks at ~32psi in the keezer at 35F. I was planning to force carbonate slowly at serving pressure to avoid over carbing.

My beer comes out of the nitro tap with no foamy head...just basically a flat beer. Having some difficulty troubleshooting the issue and hoping someone has a simple fix I'm missing. Most of what I have read online says I need to give it more time at serving pressure, but after three weeks I was expecting to at least see something close to a traditional nitro pour.

Thanks!

[RC]

It's because, even after 3 weeks, not enough CO2 has dissolved into the beer (all that foam from a nitro pour is CO2, not N2). If you have a CO2 tank, get the beer to 1.5-2.0 vols first, then hook up the nitro tank. I'll let others work the math with the gas laws, but using 32 psi of beer gas to carb a beer to even just ~1.5 vols guarantees a sloooooooooooooow carbonation timeframe.

[majorvices]

+1 - you have to carbonate it first to 1.5-2.0 vol co2.

[Lednerg]

Thank you, I appreciate the responses.

In my experience (many years with CO2, none with nitro), I will let beers carbonate over about two weeks at 10-12 psi of CO2.  Exception being if I brew a hop forward beer and want it as fresh as possible, in which case I will carb at 30-40psi CO2 over 24-48hrs then turn the gas down to serve.

32 psi of beer gas should be 8psi of CO2/24psi of Nitrogen. So after three weeks, I would expect this beer to be on the lower end of carbonated by now.

[RC]

The density of the beer could have something to do with it as well. I currently have a 10.5% RIS on tap, which finished at 1.027, and it took forever to carbonate even at 30 psi of CO2. I suspect it's like iso-alpha acids--harder to dissolve in denser solutions because there's already so much "stuff" in it. You could always shake the CO2 in. No risk of overcarbing with that method.

[majorvices]

Thank you, I appreciate the responses.

In my experience (many years with CO2, none with nitro), I will let beers carbonate over about two weeks at 10-12 psi of CO2.  Exception being if I brew a hop forward beer and want it as fresh as possible, in which case I will carb at 30-40psi CO2 over 24-48hrs then turn the gas down to serve.

32 psi of beer gas should be 8psi of CO2/24psi of Nitrogen. So after three weeks, I would expect this beer to be on the lower end of carbonated by now.

On a professional brewery scale i tried to force carbonate a BBT with beer gas through the diffusion stone and it didn't work.i'm by far a gas expert and maybe someone can get it to work, i dunno - didn't work for me.

[MDL]

I believe you need a higher pressure with 75/25.

Reason being you can’t simply take 25% of your dispense pressure to determine your co2 content with mixed gas. You have to calculate your atmospheric pressure and take the percentage of that, not gauge pressure.

Check out this website for all you need to know on mixed gas dispensing.
https://mcdantim.com/tools/calculator

FWIW, I have good results by filling the keg with flat stout and chilling to 38 degrees. Inject 75/25 into keg through carb stone at 38-40 psi. Move gas to keg in post and dispense at same pressure adjusting up or down slightly to achieve the perfect poor. Keep keg under mixed gas pressure when not in use.