reader question: nitrogen dispense for homebrew

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A while back, reader Joe J. asked

Can you school us on how you nitrogenate your beer? I am upgrading soon, and would love to have some insight.

… to which I reluctantly agreed, because there are few things I dislike more than Imperial pints of dry stout poured on mixed gas. So with my usual battery of caveats (“this is just how I do it and it works for me, but it’s not the only way, YMMV” etc.) let’s dig in.

First, some brief theory: nitrogen dispense – AKA mixed-gas dispense, nitro pour, probably some other terms I can’t recall at the moment – is pouring kegged beer with a blend of nitrogen and CO2 (instead of just CO2). It was designed and implemented commercially in Ireland and the UK to mimic the effects of hand-pumped dispense without the loss of shelf life that accompanies air influx into the spiled cask.

The gas blend is usually in the neighborhood of 70% N to 30% CO2, an approximation of atmospheric air. Because nitrogen is less soluble in liquid than CO2, it gets knocked out of solution easily and the beer gets quite degassed as it pours, which creates that iconic cascade of bubbles and a creamy, smooth mouthfeel in a beer with a pretty low delivered carbonation level.

Gear

Assuming you already have a homebrew soda keg system, here’s the list of additional necessaries:

  1. Nitrogen tank filled with beer gas. Nitrogen tanks are pressurized to a much higher level than CO2 cylinders, and they have a threaded female port for the regulator. “Beer gas mix” is what our 70/30 N:CO2 blend is usually known as when you go to fill it up.

    image courtesy MoreBeer.com

  2. Regulator for nitro tank (plus gas tubing & QD for your keg). Nitrogen regulators are rated for higher pressure than CO2 regulators, and have a male threaded fitting for the female port on the nitro tank. Fittings for gas tubing should be the same as for your CO2 system.
  3. Stout faucet (plus bev tubing & QD for your keg). It is physically possible to dispense nitrogenated, kegged beer through a regular old beer faucet, or even a plastic cobra tap, but in my experience it’s a bit like starting the engine but not driving the car all the way home. Without the restrictor plate of a stout faucet, I have found the cascade of bubbles is largely lost, the texture isn’t quite the same, and the head on the pint is less impressive. These faucets have a two-way valve that allows regular pouring when the handle is pulled forward, and then a “foaming” position when it’s pushed back to top off the last 1/3 or so of the glass, creating a very densely-knit cap of foam.
    stout faucet showing gasket & restrictor plate

    stout faucet showing gasket & restrictor plate

  4. Diffusion stone inside the keg. Because nitrogen is less soluble than CO2, pushing the beer gas through a diffusion stone (0.5 microns or so) inside the bottom of the keg ensures that the bright beer will get adequately saturated. It’s possible to Macguyver a stone clamped onto a couple feet of tubing with the other end snugged over the gas-in tube inside the keg, but a rig like this (storebought or homemade) is a bit more elegant.

    image courtesy MoreBeer.com

My process

  1. Chill & fine the beer prior to kegging. This is key, because yeast floccs, trub, and other solids will clog up the restrictor plate in the stout faucet.
  2. Rack clear beer into keg & insert diffusion stone.
  3. Connect to beer gas blend & apply pressure. I usually start at about 35 psi and adjust as needed. Normal dispensing pressure for me is usually 25-35 psi, and I prefer to err on the high side.
  4. Wait, then pour. Give it a day or so, depending on how cold the beer is. If I’m in a hurry to get it online and have a stout stat, I have been known to turn the pressure up to 45 psi or so and dispense immediately (what I did for the pint photos shown in this post), and gradually adjust the pressure downward over time as the beer absorbs more gas.

Hope this helps, Joe! Now I need to find a way to properly dispose of this nitro-poured stout.

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27 thoughts on “reader question: nitrogen dispense for homebrew

  1. I’ve been thinking of getting a nitro set up to add to my current system, but my local CO2 supplier doesn’t carry the beer gas. I may just have to dig deeper to locate a supplier – I would love to serve a Boddies style bitter from it, as well!

  2. I’ve been thinking of getting a nitro setup some time soon. One thing I’ve heard people suggest is carbonating initially with CO2 at around 8-10psi, then switching it to beer gas once it’s carbonated. That way you don’t “waste” your beer gas, and since the nitrogen doesn’t dissolve into the beer to any noticeable degree it will come out essentially the same.

    Any thoughts about this approach? Seems like you’d avoid the need for a diffusion stone with this approach.

    • Dave, I think you’ve hit on what makes this dispense method so awesome & ridiculous – working so hard to get gas into solution so it can be knocked out as it travels to the glass.

      Independently carbing with CO2 definitely works – I used to do it, but don’t anymore. I found it didn’t eliminate the need for a diffusion stone with the beer gas (headspace pressure alone wasn’t enough to force the nitrogen into solution enough to get the desired appearance/effects, in my experience anyway); and it was an extra step that I didn’t find made a significant difference in sensory or in gas usage … since nitro pouring uses a fair amount of gas just to dispense, I don’t really notice that much of an extra drain on beer gas doing it this way.

      Hope this helps – have fun with your future nitro setup!

    • You are right, That Guy! Beer gas is just an approximation of atmo gas, though, just like nitro dispense is – arguably – a derivation of hand-pumped cask ale. Nobody go demanding 78% nitrogen at the gas cylinder exchange place.

      • I guess I wasn’t quibbling so much about 70 vs 78% N2, more so the 30% CO2. That’d be like 300,000 ppm CO2! Talk about green house gases! I’ll shut up now.

        • To be clear, atmospheric gas, the stuff we breath, is mostly nitrogen and oxygen. That 1% I quoted above contains the CO2 in the atmosphere; current measure is 401 ppm, or 0.04%. Beer gas is just two gases: nitrogen and carbon dioxide, no oxygen. That’s all. Sorry again for being that guy.

  3. I’ve read that some note a “metallic” taste to their beer when it’s carbonated with beer gas. Do you experience any of this? Does it come with the territory? Before reading your explanation, I was under the impression that most carbed with CO2, then dispensed with beer gas.

    Also, do you formulate recipes differently when brewing for a nitrogen dispense? Maybe anticipating a muting of flavors or bitterness?

  4. Good read. For a year and a half I’ve been jacking up the pressure to 40 PSI for several days waiting for the headspace to carbonate the beer. Just ordered a keg lid/ carbonation stone kit, hoping to improve on this.

    Any luck putting other styles other than stout on nitro?

    • I am sure you will shave entire days off your waiting period! I do like the lower-shilling Scottish ales on nitro; maybe the occasional bitter, but I find it does blunt the hop character quite a bit. How about you – any other styles besides stout?

          • Cider does sound like a great experiment. I’ve done an irish red on nitro but other than that havent gone too far from the dry stout. A bitter and a cider i think will be soon to come!

            • I’ve served several ciders on nitro over the last 2-3 years. IMHO, cider on nitro is sublime; it’s a different beast than serving on CO2, (nitro seems to impart a fuller body and a sturdier head than CO2), but it’s most definitely a worthwhile experiment to see if you like your ciders on teh nitro, as the kids say these days.

  5. Not sure if I’m doing this right, but I when I did my nitro setup I went with a CO2 regulator + CO2 to Nitro adapter (combined, its half the cost of a “Nitrogen Regulator”). IMO, as long as the regulator high pressure is 3000+ PSI (Nitro is filled to around 2k PSI) and 60+ PSI for the low side (serving pressure being around 40ish) this setup is fine. It seems to me like the nitro regulator is just a now-a-days common CO2 regulator with the male flare type connector to go into the female socket of a nitro tank. Nitro regulators were probably required in a time when CO2 regulators were too low of a pressure to handle nitro. I’m basing this assumption off of some old CO2 regulators with lower pressures that I’ve seen.

    Anyway, I’ve been rocking this setup with great success since Jan/Feb. No nitro leaks and, more importantly, no exploding regulators!

    • Thanks for the info, Jake! I don’t have any experience with this particular workaround, as my CO2 regulators are of a pretty vintage vintage.

  6. Hey fellas, been kegging since feb and I have the family to look after so I just gotta ask: do you think I could create the cascade effect without investing in a nitro system? One of my first kegged brews was an Oatmeal stout, duely all grain, and I compromised on the setting for all of my beers(pilsner, hefewiezen & strawberry watermelon wine) at 12 PSI which I estimate to be 2.5 volumes CO2 at 36*F. I had found that given a beer with higher sg due to unfermentables (oatmeal stout FG was 1.020, also a strong dark beglian ale OG 1.088/ FG 1.024) that beer will foam( or release CO2) more due to body than a thinner beer. Also I found that with my cobra taps I could vary the amount of foaming by pouring most of a glass and then reducing the flow to spray the brew at the last 1/4 pint I could get a lovely head on the stout. I believe that with a lower (appropriate) setting on a keg of stout (maybe 1.5vol CO2) anyone could use this (free) method to create that commercial effect upon serving with no additional cost required. Isn’t that the jarring required to knock some CO2 out of solution. Next brew for me will be a smoked cherry porter!

  7. Foist off, I have watched a bunch of your videos and they are uniformly excellent. As for this post, I followed the tips, got the diffusion stone, and am now drinking an imperial pint of my very first home-brewed stout, a Guinness clone I call Duinness. (Get it?) I based it off the recipe in the All About Stouts video you did with Northern Brewer. It’s awesome. Very, very close to actual Guinness. To the degree mine isn’t– well, I’m a novice and I added too much roasted barley. Even still, it’s killer. Thanks for posting all the great tips!

  8. Do you still follow the same schedule for carbonating? How long are your draft lines? Cold crashing my first nitro beer now and hoping to keg it next week. Thanks for the write up!

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