Nitro Serving Pressure Sanity Check

Just checking that my logic is sound: if using 25/75 beer gas, I would multiply my normal CO2 serving pressure by 4 to get my beer gas serving pressure (100/25=4).

For example, if I would normally set my serving pressure at 5psi under CO2 alone, I would set it at 20psi on beer gas.


If you are not pushing the beer a longer distance, you should have the regulator set for about the same PSI’s.

Otherwise you will have a fire hydrant spray coming out of your faucet.

Assuming you are serving from a propper stout faucet, then the common pressure is 20-30 psi. The stout faucet (assuming a very low carbonation in beer) is designed for this.

If you are serving from a standard faucet, then see Nighthawks comments.

From my experience if the beer is perfectly carbonated, the high pressure does produce the perfect pint.

However, at this serving pressure the beer overcarbonates extremely easily. DO NOT leave the gas on all night by accident or its will be pure creamy foam by morning.

My basic process as best I can manage it (again, assuming a stout faucet):

  1. start serving when been is slightly undercarbonated - is still ver rich and creamy with the nitro. The high psi will get the carbonation up to a good level within a few hours of use while drinking it.

  2. When perfect pints are coming out I become a little more carefull to have gas on only when in use, and usually will bring the psi down to 10-15 just to be safe. Also release a lot of keg pressure at then of the night.

  3. By the end of a keg most of my stouts/bitters etc, end up a little over carbonnated at which time I will either serve at 5-6psi, or just turn off the gass and let the beer push itself through for a few pulls. Degassing the keg as I do this can help get the carbonnation back to where I want it.

I definately find the beer gas/ stout faucet set up a little more of a chore to control, but it is worth it when those velvety smooth guiness clones are coming out.

Yes, I’m serving out of a stout faucet. I carbonated on CO2 first. I let the beer sit overnight on beer gas at 30psi last night. It’s exactly as you described: a lot of foam. Maybe I’ll vent it and let it sit overnight with no gas on it and see how it is in the morning.

After you carbonate with CO2 to 1.5-1.8vol, vent the keg and hook up your beer gas blend at 30 psi.
Let this sit overnight and no worries keeping it at 30 psi throughout the keg’s life. You’re only pushing 7.5 vol of CO2 into the beer, so over carbonation is highly unlikely.
If this were the case, Guinnes at bars would be foamy since bars never cut gas off.

I usually serve beers on nitro 2-3 times and year and have no problems. Venting after carbonating with CO2 is key to great looking cascading imperial pints from day one.


After doing some more reading, I think my problem is that I over-carbonated my kegs for this application and did not purge the headspace prior to attaching beer gas. Lesson learned. Now I’ve got just a few days to fix it!

I use 5 ft. lines normally and get a perfect pour on CO2. I wonder if I should perhaps use longer lines when serving on beer gas. 10? 15? 20? Thinking 20 since I can easily cut them down from there if needed.

If you are using a stout faucet with a restricter plate, that should drop the the higher pressure of the beer gas mix.

Here is a nice writeup on using beer gas mix.

But if you started with an over carbonated beer, you might need to degass it. You could leave the PRV open for a half hour or so and see where it sits.

I had one over carb on me years back. I took it out of the serving fridge and let it warm to room temp for 9 hours, venting and gently rocking the keg whenever I walked by.

Thanks for your advice guys. I was able to get it fixed and my Irish stout was a huge hit last night. A friend who has had his fair share of Guinness in Dublin kept going back for more and said it was as good as a Guinness in Dublin. I think it’s close. Either way, beats the crap out of a Guinness in the US.

Anyway…It was definitely over-carbed. Last Thursday I rolled the keg on the floor (purging periodically), and then left it in the keezer overnight without any pressure. After purging what was left in the headspace, I put it back on beer gas. I ended up serving on 15psi with good results. The cascade effect was very weak if I lowered it to regular serving pressure. I didn’t go higher than 15, because I didn’t want to risk overcarbing before the party. Just to be safe before the party, I turned off the gas overnight. Now I may experiment with higher pressure to see what happens.

Nice pic, but crank to at least 30 psi. You won’t overcarb. Mine has been at 30 for over a week and pours great. Plus, you won’t get the cascading without more pressure.

I got some cascade at 15 psi, but it wasn’t overwhelmingly impressive. Will definitely go higher after give my liver a few days to rest.