Root beer on a stout faucet

[steveman0]

Cross-listing this from the soda forum since it might get more relevant experience here...

I'm currently working on the plans for my keezer build and want to allocate a faucet for root beer. I've seen some talk of using a stout faucet for this and really like the idea of a nitro head on a root beer. Does anyone have experience with this to say whether this works in practice or not?

If so, what considerations are there for the setup? Obviously the faucet is one and I'm trying to decide before putting in the extra money for the faucet vs. a standard one. Would I still carb to standard root beer volumes (30-35 psi CO2)? Serve on beer gas at the same pressure as beer? Would this setup still require the extended serving line or would the restrictor plate be enough to control the foaming?

 

[day_trippr]

It's apparently been done successfully.
"I have a dedicated nitro setup on my kegerator for rootbeer (well, one stout tap for the stout, and another for root beer, in addition to the beer). I carb my rootbeer at 15 PSI and nitro dispense at 35 PSI. Pours like a Guinness, gorgeous cascade and creamy head."

fwiw, having maintained my house triple chocolate imperial stout on a nitro stout tap for years now the author's nitro dispensing pressure is the same I use but I am surprised at the stated carbonation level (way higher the 1.3-1.4 volumes of CO2 I use). That said root beer is decidedly different from a stout so I'd go with the author on that one

Cheers!

 

[steveman0]

Thanks for the find! I'd overlooked the details in that post. I'm surprised at the low carb on the root beer - typical soda carb levels are at 20+ psi and I like mine on the higher end.

I've been thinking more on the subject and wonder about the physics behind nitro pours in general. I feel like with a root beer as you empty the keg (especially with a higher initial carb level) the root beer may become flat as the partial pressure of CO2 in the beer gas isn't enough to maintain it in solution. I think I have more reading on the subject...

It's good to get confirmation that serving pressure appears to be the same as that means a single regulator is all I need to serve my beer (on a separate stout faucet) and root beer simultaneously.

 

[mack25]

hey that was my post I can add that I tried carbing from 5PSI to 15, and 15 worked best, and 35 for the beer gas.

 

[steveman0]

Nice to see you are still around! Did you have any issues with it going flat over the time on tap?

Here's my full thought process on it...
For a regular nitro beer a normal length line is pressurized with ~35 psi. The stout faucet serves as the primary restriction dropping the remaining 25-30 after the line's restriction is accounted for. This provides the creamy head associated with the faucet. To do this a nitrogen blend is required to achieve the necessary pressure at the stout faucet without overcarbing the beer. For a 25% CO2 blend the partial pressure of CO2 will be ~9 psi which is a fairly normal carb level for the beer.

In the case of a root beer, typical carb levels exceed 25 psi and could be as high as 30-35 psi as I like it. In this case there's enough pressure for the stout faucet restriction. Perhaps it's better to push it with straight CO2?

With the 25% CO2 beer gas blend the partial pressure of CO2 is only a fraction of what the root beer would be carbed at so once head space is formed in the keg the root beer would begin to go flat. If pushed with straight CO2 this isn't an issue.

My worry is that 15 psi CO2 carb level for the root beer is not going to be enough for my tastes and I'll want to push it higher especially given that over time it may reduce to the equivalent of a 9 psi carb. But I don't know how the stout faucet will respond in the case of straight CO2 especially at those volumes. Can it be counteracted with longer dispense line as normally done?

It may just require some science. I think I'll at least commit to the stout faucet as I think I can find a way to make it work. Additionally, I'm planning to buy 50' of dispense line since my 20' section wasn't quite enough. That should give me some flexibility for experimenting into new territory.

 

[mack25]

Never had any trouble with the keg going flat over time. then again, the keg never lasts that long...

If I had to guess, I would say that at 25 PSI of Co2 it will probably be over-carbed and you will get a glass of only foam. But then again, soda lacks the proteins that beer has, so maybe not or maybe it will settle out. I suspect that's why 15 PSI worked for me - more gas than beer to compensate, but less than soda.