Q. I am interested in experimenting with home pasteurization. Over the years, I’ve read that adding fruit to fermented beer, backsweetening cider, and now making no- and low-alcohol beer are all good candidates for pasteurization. Is there a way to pasteurize at home without embarking on some sort of crazy project?
Taylor Carter
Lille, France

Mr. Wizard says…

A. Although Louis Pasteur is best remembered for milk pasteurization, his original method was developed for beer. And the cool thing about the process we now call pasteurization is that it’s pretty darn simple.

Until the advent of in-line heating and cooling, pasteurization was a batch process. In fact, batch pasteurization is still commonly used by small-scale producers to render products safe and shelf-stable. But the history of beer is more about how advancements in science and engineering allowed brewers to grow large. Pasteurization is at the heart of that history. Brewers were quick to take note of Pasteur’s Études sur la bière (Studies on Beer), and Carlsberg was the first brewery to pasteurize beer for commercial sale in the 1870s. 

As my mentor and professor to many Dr. Michael J. Lewis repeated in every lecture on packaging: Pasteurization allows a brewer to sleep at night. In practical terms, this is because worries about microbiological spoilage and unwanted secondary fermentation are simply erased. 

The good news is that you can easily pasteurize beer at home with just a few simple pieces of equipment. Depending on your setup, you may already have the basic tools. But before discussing how, let’s review the what. Pasteurization at home is performed using a batch method. In essence, this is just atmospheric canning: Prepare a hot water bath, load it with bottles of beer, and process at a set temperature for a set time. A typical pasteurization process used for the range you ask about is 50 Pasteurization Units (PU), where 1 PU = 1 minute at 60 °C (140 °F). The relationship between temperature and pasteurization rate is exponential, expressed as:

PU = t x 1.393^(T-60)

Where “T” is the product temperature in °C and “t” is time in minutes. Using this equation, it’s easy to see why just a few degrees make a big difference. For example, 1 minute at 65 °C (149 °F) equals about 5.2 PU, so 10 minutes at that temperature yields roughly 50 PU. The current recommendation for non-alcoholic beers is about 75 PU, or around 15 minutes at 65 °C (149 °F). The time and temperature together are known as the thermal process.

The main challenge with all types of pasteurization is starting the timer at the right moment. If your process is 15 minutes at 65 °C (149 °F), the timer doesn’t start until the coldest spot in the bottle reaches 65 °C (149 °F). Commercial producers use in-line probes and in-package sensors for this. Smaller producers often use a test bottle fitted with a thermometer to monitor the process. 

If you want to pasteurize at home, one key is to use far more water in your water bath than the mass of product added. This helps prevent a big temperature drop when you add your bottles or cans. A properly sized heater and water pump are also needed. In a nutshell, a large reservoir of water is heated to a temperature a couple of degrees higher than your target process temperature. Because bottled beer has a large thermal mass, you need a heater capable of making up the heat loss. That’s the engineering part of this answer that I’m choosing to skip — but for the curious, that means considering the heat transfer coefficient between glass and liquid, the specific heat of the product, and the total wattage required to maintain a uniform thermal field. Even a 1500-watt immersion heater, when coupled with a small circulation pump, can maintain a 20- to 25-liter bath with less than ±0.5 °C variation (5–7 gallon bath with less than 1 °F). Circulation eliminates stratification and ensures that every bottle follows a near-identical heating curve. For the more technically inclined, thermocouples or data loggers can be used to integrate the pasteurization curve and calculate total PU delivered. After the bottles are added, the process sensor is monitored, the timer started once the target temperature is reached, and the bottles removed after the timer has elapsed.

Over-pasteurization can result in cooked or oxidized beer. Cooking can be controlled by establishing the minimum process required to achieve your goals, and oxidation is minimized by reducing oxygen pickup during packaging. The key point is that the thermal process should be ended by cooling as soon as possible after pasteurization is complete. 

Q: Can I put ascorbic acid in my cans before I fill them with beer to scrub any dissolved oxygen? Also, how would I dose it?
— Darren O’Day • Philadelphia, Pennsylvania

Mr. Wizard says…

A: Ascorbic acid, also known as Vitamin C, is indeed an antioxidant often discussed in the context of beer stability because of its ability to scavenge oxygen in the headspace of packaged beer. Its mode of action is somewhat different from many other antioxidants. Ascorbic acid does not directly bind oxygen. Instead, it donates hydrogen atoms to reactive oxygen species such as peroxide radicals, thereby neutralizing them. This transfer of electrons is the fundamental chemical process we call oxidation.

However, the behavior of ascorbic acid can be complicated by the presence of transition metal ions, particularly iron and copper (Fe²⁺ and Cu²⁺). In the presence of these metals, ascorbic acid can actually promote the generation of reactive oxygen species rather than prevent it, effectively reversing its antioxidant role and causing oxidative damage. For this reason, successful use of ascorbic acid requires very low levels of these metal ions. Unfortunately, in brewing, keeping metals out can be difficult. Common brewing inputs such as hops, malt, brewing water, and filtration aids can all be sources of copper and iron. But for the sake of discussion, let’s assume a beer with minimal problematic metal ion content.

When used under the right conditions, ascorbic acid is safe for beer, though flavor limits must be respected. At higher concentrations, it imparts a noticeable tartness. The threshold for this effect varies depending on beer style: Light, delicate beers can show tartness at concentrations above about 10 mg/L, while more flavorful or heavily hopped beers can tolerate slightly higher levels. As is often the case in brewing, bench trials are invaluable for determining the appropriate dosage for a specific recipe. A common working range is 5–10 mg/L.

The most practical way to add ascorbic acid is as an aqueous solution. Because the compound itself is reactive toward oxygen, the solution should be prepared in deoxygenated water — ideally water that has been boiled, cooled, and stored in a sealed container to minimize oxygen pickup.

The dosage calculation is straightforward when using metric measurements. For example, suppose you are working with 20 liters of beer and wish to dose at 10 mg/L. That requires 200 mg of ascorbic acid in total. Since the solubility of ascorbic acid in water at 68 °F (20 °C) is about 330 g/L, there is no risk of creating an overly concentrated stock solution. A convenient approach is to prepare a 40 g/L stock solution. 20 mL of this solution will contain the required 200 mg of ascorbic acid for the 20-L batch. Unless you have a highly accurate scale, mixing up 4 g of ascorbic acid in 100 mL of water is easy to measure and gives you plenty for bench trialing and dosing. 

Q: I have a question about storing kegs after they’ve been cleaned and sanitized. I had a bad experience when I had purged a keg with CO2 and stored it that way for months before using it for kegging. On the day we were going to keg, I popped the lid and got a very strong, pungent odor from the keg. I would say it was even acidic, as if carbonic acid gas had formed over time. How could this have happened? Perhaps I left too much sanitizer in the keg, though I do my best not to do that. Or maybe some other contaminant was present because I didn’t clean well enough? Or perhaps this is a natural process that occurs over several months and the long-term storage of kegs needs to be done differently?
— Jeff Vandewinckel • Arlington, Tennessee

Mr. Wizard says…

Your example is an extreme case between sanitizing and use, but the broader question is one I’ve often heard craft brewers discuss when preparing equipment. My preferred method is to clean equipment immediately after use, then sanitize just before use. Fermentation vessels, for instance, are easiest to clean shortly after emptying. Often, a simple water rinse with gentle scrubbing, followed by another light rinse and then a cleaning cycle — either by hand or with a pump and spray ball — is quick and effective. Some brewers then sanitize the vessel and store it closed and under pressure until needed, as you describe.

The real issue with cleaning and sanitizing is that neither process is absolute — sanitized equipment is not sterile. And because no-rinse sanitizers used in brewing and food processing rarely provide residual activity, any surviving microorganisms can grow if nutrients are present. It’s impossible to know exactly what developed in your keg during extended storage, but the sour smell is a clear indicator that something did. Carbonic acid itself is odorless, but when you sniff carbonated beverages, it creates a tingling sensation in your nose. By contrast, organic acids such as acetic, propionic, and butyric have sharp aromas that are easy to detect.

Going forward, I recommend cleaning equipment immediately after use, allowing it to drain, and then storing it. Dust is difficult to control at home and can carry yeasts, molds, and bacteria. A quick rinse followed by sanitization right before use is the best practice.

Q: I am having an issue with a stout in which I used 75% nitrogen/25% carbon dioxide beer gas mix. It’s been kegged for six weeks at 33 PSI and held between 36–37 °F (2–3 °C). The beer barely cascades (basically nothing) pouring from a stout faucet. I’m new to using nitro, but have been brewing for 15 years and have no issues with my other beers. I’m starting to question if the stout tap is good.
— Ken Schretlen • via email

A: When it comes to pouring stout, there is a clear gold standard to match: That’s Guinness. A brief review of a few key things known about Guinness draft stout helps troubleshooting. According to numerous references, Guinness contains a paltry 1.2 volumes or 2.4 g/L of carbon dioxide and about 55 ppm of nitrogen (level reported from a brewing scientist in England with knowledge about this specification). These gas specifications align with beer equilibrated with a 75% nitrogen/25% carbon dioxide gas blend at 33 PSI and 36 °F (2 °C).

Although U.S. nitro brewers use the gas mix and conditions you used, Guinness specifies in their Draught Quality Standards publication a 70% nitrogen/30% carbon dioxide gas blend at 32–40 PSI for kegs stored at 46–50 °F (8–10 °C) and chilled in-line to the faucet to 39-43 °F  (4–6 °C). This reflects differences in beer handling practices in the different parts of the world selling Guinness.

If low nitrogen content is your problem, one cause is insufficient headspace in your keg. An easy thing to try is to simply pour off some beer, let your beer rest to re-equilibrate or lay your keg on its side and do some shaking to speed things along, and check to see if you have more cascading. If you do, it’s an indicator that this strategy is working. Either keep rocking your keg until you hear gas flow stopping or let your beer sit for several days to allow gas transfer between the headspace and beer to occur.

Another possible cause of no cascading is insufficient velocity flowing through the faucet. The classic Guinness faucet requires turbulent flow occurring as beer is forced through the five tiny holes in the restriction plate or so-called jet disk. Some brewers make the mistake of reducing the keg pressure to “normal” beer pressure before serving or make the mistake of trying to balance the draft system by using the line diameter and length rules used for normal carbonated beer. Both mistakes result in low velocity and little to no gas breakout as beer flows through the jet disk. Guinness provides a 12 second target for the first part of their classic two-part pour. This translates to 1.25 ounces (37 mL) per second. If your flow rate is too slow and your keg pressure is about 33 PSI using a 75/25 gas blend, you have too much line restriction or your restriction plate is clogged. Start by checking the restriction plate; if clear, it’s time to do some line replacing using a minimal line length between keg and faucet.

In my experience, poor cascading and foam formation in nitro beers is typically caused by inadequate dissolved nitrogen. Although high gas pressures can be used to increase the gas transfer rate using what I call the crank and shake method, gas control is approximate at best. The most reliable way to quickly nitrogenate your beer is to lay the keg on its side, position your gas cylinder above the keg to prevent beer from flowing into your gas line, pressurize the gas line, connect it to the keg with the gas line positioned at 12 o’clock to prevent excessive foaming, and allow the headspace to pressurize.

Once the keg is pressurized to ~33 PSI, begin rolling the keg back and forth. As gas dissolves into the beer, pressure in the line drops, and the regulator allows gas to flow. This is audible and is a direct indicator of gas flow into the beer. As dissolved gas content approaches the equilibrium condition and gas flow slows, you should hear a change to the sound of the operation. When you can no longer hear gas flowing, you are close to being done. I find it works well to allow the keg to settle for about 15 minutes and repeat the rocking step. When no gas flow can be heard when rocking your rested keg, it’s time to let the keg rest upright for an hour or so before pouring a pint. If you don’t like this idea, simply connect your keg to your gas cylinder, set the regulator pressure to ~33 PSI and let the system sit for a week.

Today’s technical discussion for homebrewers with a draft system is the ever popular and sometimes mysterious topic of system balance. Having seen dozens, if not hundreds, of YouTube videos and online discussions, I recognize that there is a tremendous amount of bad, confusing, or simply unhelpful information out there on the subject. It sometimes hurts my head because the how and the why is not really all that puzzling. Over three pages in this column, I will explain in simple language and dismantle some of the myths surrounding draft system design. You can trust me, I am a professional (draft system installer/servicer) who also maintains multiple kegerators at home.

A balanced draft system will pour a perfect pint, with the proper amount of foam, at the proper temperature. A perfect pint is that beautiful beer that has the desired foam collar and does not waste beer. We want to get that perfect pint every time we pour with little fuss. Serving your homebrew from a bottle is cool. Serving that homebrew in a perfect pint is outstanding.

If you have ever messed around with line diameter, line length, temperature, applied pressure, or felt like you needed to change equipment in pursuit of the perfect pour, this article is for you. Let’s get to pouring the perfect pint and stop dumping foam. You worked hard for that homebrew — don’t waste it. This summary of system balance will discuss the how and the why while simultaneously describing corrective measures. I have found that most discussions about system balance don’t get into why, but are quick to tell you what you should be fixing to adjust your system. The truth is that system balance requires a simple understanding of temperature, pressure, and resistance, the rest is quite intuitive. With some patience, you can learn to identify and correct foaming issues with your draft system, starting with the most common problem. 

There are only three variables in any draft beer system: Temperature, pressure, and resistance. In that order. That’s it, and it means you only need to think about three possible issues to address when your pours aren’t right. Your system might need corrections to one, two, or all three variables, but once you know how each variable affects your draft beer, the needed changes are not very difficult.

Think of system balance as a three-legged stool. Each leg is equally important, and if one leg is out of whack you do not have a solid seat. When all three legs are adjusted accurately, the stool is stable. 

Temperature

Temperature problems make up the majority of draft-related headaches. Fortunately, it is also the easiest to diagnose and cure. First, the beer in the keg should be at 38 °F (3 °C) and the beer in your glass should be the same temperature. If you find that the beer in the glass has warmed by even one or two degrees, you will be pouring some foam. If you like your draft beer warmer than 38 °F (3 °C), well, things are going to get much more difficult. You want a perfect pour? Then 38 °F (3 °C) it is. A degree or two colder won’t have a significant impact, but a few degrees warmer and things can get squirrelly. It is not impossible to get a good pour at 44 °F (7 °C) (with additional pressure and more line restriction to balance the system), but since you are presumably reading this because your system is not perfect, let’s try to get a good design at 38 °F (3 °C) before we start experimenting.

Place a glass of water inside the kegerator and leave it alone until the temperature stabilizes. Use a quality thermometer and measure the temperature. Compare it to the temperature of the first 3 or 4 ounces of poured beer. If you are off by a few degrees, it indicates that the beer in the line is warming. We need to correct that problem and it might require a fair bit of homebrew ingenuity.

The colder the liquid, the more dissolved carbon dioxide (CO₂) the liquid can hold. That is dissolved CO₂ gas, before it has become foam. The dissolved gas will break out of solution in the beer line and then you’ll have a slug of foam as you open the faucet and pour. The foam will rise to the highest point in the line. If you have a quick burst of foam followed by clear beer, your warm spot is near the faucet. If you have clear beer, a bit of foam and then clear beer, the foam is rising to a bend somewhere in the beer line. If you pour some foam and then consecutively pour perfect pints, surely it is a temperature problem occurring after the keg.

Identifying temperature-related foam is not hard, but correcting the problem can sometimes be a chore. As we have determined, we need to maintain a constant temperature from keg to glass. In practice this is not always possible to execute to perfection with a home draft system. But we can get very close to perfection. First thing is to be sure all gaps are sealed in the refrigeration unit. Place a bright light inside the kegerator, close the door and turn off the lights. Look for light leakage. Seal those however you can. Next, be certain your draft tower is sufficiently insulated. It is not uncommon, or even a problem, when the tower sweats. That is water vapor condensing on a cold surface. If you have a lot of sweat on your draft tower, it’s because the metal tower is absorbing ambient heat. The line in the tower is likewise gaining some heat. Well-placed insulation can help. I caution, however, don’t overdo it. Dumping a can of spray foam in the draft tower is not a solution because we are going to want to cool the tower, and that requires air flow.

Higher-end kegerators will always have a fan and tube assembly to get cold air into the draft tower, all the way up to the faucet. Be sure the fan is working and that the tube is extended all the way up into the draft tower (it is a costly service call to show a client where that dangling hose is supposed to live). If you don’t have a fan, fear not because the fine folks at Amazon (and other retailers) have you covered. A small fan with 20 to 50 cfm is plenty. More than that, and you’ll start to force air out of the gaps you carefully sealed. Place the fan near the cooling coil, if possible, and direct the tube all the way up to the shank. Now you have a top-of-the-line kegerator. Congratulations. Cooling the tower is not just important, it is required if you want that first pour to be as good as the second. The cold air from the kegerator is not going to rise up to the faucet and shank on its own, and you will have foam if you do not keep the beer within the tower cold. The tower fan can fix it. 

Next thing to consider with temperature, though it is unlikely, is you may have a problem maintaining keg temperature. Cheap refrigeration units feature cheap parts and that includes the internal thermostat. If the factory set cut in/cut out temperature variable is too large, it is possible that the keg is not holding a consistent temperature. This is especially true when a keg gets to the last few pints. The liquid will gain heat faster than it will chill down. If your compressor is not cycling enough, the keg might be warming and releasing CO₂. An outboard thermostat will fix this. It might also burn out the compressor prematurely, but that is the nature of a cut rate appliance. If your keg is not maintaining temperature, surely your draft tower is not either. 

So that’s temperature. By far the most important variable but also the easiest to fix and diagnose. Before moving to any other corrections, be certain that beer temperature is sorted.

Pressure

Foam is not often caused by too much applied pressure; instead it is often a result of too little applied pressure. How is that possible? Relating that dissolved CO₂ is gas that remains within the liquid and foam is gas that has escaped from the liquid as it equilibrates with atmosphere, we want to be sure the dissolved CO₂ content is maintained from keg to faucet. If your keg of beer has 12 psi of pressure applied at 38 °F (3 °C) you will eventually achieve 2.6 volumes of carbonation. As you are now maintaining temperature, you should be maintaining applied pressure. 

Here is the rub: It is tempting to adjust the applied pressure to fix foaming problems. There are two convenient knobs. One is the thermostat and the other is the regulator. 

Hold on. Adjust the temperature and you are messing with one of the legs of the stool. We need to hold 38 °F (3 °C) first and foremost. Lower the applied pressure and now you have gas escaping from the beer in the keg, and also in the beer line. The keg doesn’t end at the coupler or quick disconnect after all. The beer doesn’t know it’s all one big system until it is poured into your glass. Now you have foam. 

The next thing is to overcorrect and dial it back. Then, when we still have foam, we overcorrect and apply additional pressure. There is no immediate effect, but eventually the beer absorbs too much gas and your resistance is out of balance. 

One more reason to diagnose temperature first: I think homebrewers can really up their game by dialing in proper carbonation levels, so adjusting pressure outside of the ideal range shouldn’t be the first solution. Along with malt, hops, yeast, and water, CO₂ gas is incredibly important but too often neglected. If you have not approached how to establish and vary the CO₂ volumes in your beer, I think you’ll be very satisfied with the results once you do. And once you do, you know to maintain the volumes in your draft system. If you feel the need to nerd out about volumes and applied pressure, check out this previous “Advanced Brewing” column “Gas Dynamics” from the November 2023 issue dedicated to your regulator: www.byo.com/article/gas-dynamics

Resistance

Resistance is one and done. When you have it right, you will not need to adjust resistance again. Resistance is simply the sum of friction from the keg to the glass. Here is a quick analogy to help us understand resistance. The spigot on the side of the house will blast water when fully open. Attach 100 feet (30 m) of garden hose to the fully opened spigot and you’ll see that the flow rate at the hose end has been significantly reduced. That is because the friction in the hose slows the rate of discharge. 

We want our draft system to have the appropriate resistance; neither too much nor too little. A balanced system is just that, meaning all three variables are working together and delivering the perfect pour. The thing with resistance is that we can’t easily change it up like we can with pressure or temperature (but there is a hack only available to homebrewers, which is necessary when pouring beer styles at different carbonation levels, which I will get to later).

The usual draft system, a kegerator or keezer, requires a certain length of choker. Choker is an appropriate term, because it chokes the rate of flow from keg to glass. With no choker, the beer will spew out at a rate equivalent to the applied pressure. Beer that pours at 12 psi is coming out like a firehose and impossible to tame in the glass. Chokers in America are universally 3⁄16-inch inner diameter and usually 7⁄16-inch outer diameter (check out a deeper dive into tubing in my previous article “Choosing Tubes and Hoses” at www.byo.com/article/choosing-tubes-and-hoses). You’ll need to know the specific resistance of your choker. It will be between 2.2 psi and 3 psi. This is important. If your supplier can’t tell you the resistance per foot, keep looking because it is the most important and only important variable we are working with. 

Let’s assume we have the best available, thermo-plastic extrusion (TPE) choker. This is free of BPA and phthalate, and oxygen impermeable as well. It will have a resistance of 3 psi per foot. A keg with 12 psi of pressure will require 4 feet of this tubing to be balanced. But we also need to consider the shank, faucet, and coupler, so add around 1⁄2 psi of resistance. Therefore, our 12-psi keg needs 12.5 psi of resistance, or 4.2 feet of TPE tubing. Finally, gravity adds resistance. Precisely 0.45 psi per foot of lift. Round this up to 0.5 psi. Measure from the middle of the keg to the shank and add the appropriate resistance. We need about 13 psi of resistance in this theoretical set-up. 

Now, here is where we can let loose a little bit. Because in theory, a balanced system is ideal. In practice, your home bar is not serving pint after pint all night long. We can relax a few extra seconds while the beer pours, and a few extra seconds makes a huge difference. You really don’t need to pour a pint in eight seconds, but you really do want to take a moment to get a great head on that beer while not dumping any at all. So let’s add a few pounds of resistance. I like to see eight- to ten-second pours on commercial systems. Eight seconds is beneficial at a busy sports bar, and dumping a little is sometimes OK in the name of speed. An evenly balanced system will pour a pint in about eight seconds. Ten seconds is more profitable for a craft bar when the kegs cost serious money and the customers expect a nice pour. A home bar can go to 15 psi of resistance without any problems, and allow for a much better controlled pour with a great presentation. The speed of the pour affects foaming in the glass. It is hard to tame the beer when it is flowing too quickly.

Now, about that resistance hack for beers intended to be poured at different carbonation levels that I mentioned earlier. We can change our choker fairly quickly. Simply install a few John Guest quick disconnects at the coupler and before the shank. Fabricate a few different lengths and you can go from 12 psi of resistance to 18 psi of resistance quickly. Or any resistance. This is helpful when trying to pour beer styles that require high volumes, like a Belgian golden ale or a hefeweizen.

Before we move on, I know what some of you are asking. “What about flow control faucets?” Simple. If your system is out of balance, flow controls will pour foam slower. The CO₂ does not stay in solution because we installed flow control faucets. If your foaming is caused by velocity — that is the beer is hitting the glass too hard — correct your pouring technique. Flow controls can help in this situation, but you probably should first reconsider the amount of system restriction.

So those are the three variables, and you can see it is not all that difficult to get a balanced system. If you are ambitious and want to explore designing and installing a complex long-draw system, I covered that topic in the December 2022 issue, online at: www.byo.com/article/long-draw-draft-system.

Q: If you’re adding priming sugar when bottling, will any oxygen that gets into the bottle be scavenged by the residual yeast during bottle conditioning? Do you have to worry about oxygen causing your brew to become stale?
— Michael Roth • Evansville, Indiana

A: Oxygen is a problem for beer at all stages of the process following the early stages of fermentation because many of the flavor-active compounds created by yeast are changed, i.e., chemically oxidized, when exposed to oxygen. Unfortunately for us brewers, these oxidation reactions are very fast and many of the products of oxidation are easily detected. It’s also a bit of a bummer that yeast typically do not mop up oxygen faster than it can react with beer flavor compounds.

When I was a young brewing student in the early 1990s, the most common method used to measure air in packaged beer was with a Zahm and Nagel headspace gizmo. These setups have a piercing device that allows for the measurement of pressure and temperature in bottles and cans; pressure and temperature are then looked up in a Zahm and Nagel chart to determine how much carbon dioxide is dissolved in the beer. The Zahm and Nagel device can be equipped with a separate apparatus that allows gas to literally be shaken out of the beer sample where it flows into a special glass burette filled with sodium hydroxide. Carbon dioxide is consumed by the sodium hydroxide but nitrogen and oxygen (not much present in beer because of its reactivity) remain in the burette and are measured as headspace air.

In the early ‘90s, it was not uncommon for packaged beer to contain 0.5 mL, and often more, of headspace air. This equates to about 400 parts per billion (ppb) of dissolved oxygen (DO). Today, brewers become concerned when their package DO is above ~30–50 ppb of DO. Packaging technology has made enormous strides over the last 30 years, as have methods used to measure DO.

I tell this story because homebrewers have become hyper-concerned about oxygen because commercial breweries are hyper-concerned with DO. Our concerns as homebrewers are like those of commercial brewers, except for one main difference; homebrewers don’t have to worry about our beers sitting in some unknown place at some unknown temperature for extended time periods waiting to be picked from the shelf. I think it is very important for homebrewers to keep that fact in mind when worrying (or not worrying) about certain brewing details. 

Empirically, it does seem that bottle-conditioned beers taste oxidized less often than other beers. This observation is well-documented in the homebrewing and commercial literature and is usually attributed to yeast being able to scavenge oxygen. I have never been sold on this explanation because oxidative reactions are faster than oxygen uptake by yeast. Indeed, research over the last 20 years or so provide clearer explanations of these empirical observations. A study by D. Saison, et al., in 2010 titled “Decrease of Aged Beer Aroma by the Reducing Activity of Brewing Yeast” where aged beer containing aged beer aromas was almost entirely stripped of these staling aldehydes during refermentation (Journal of Agricultural and Food Chemistry 2010 58 (5), 3107-3115). A more recent study in 2023 by De Clippeleer, et al., related to non-alcoholic and low-alcohol beer (NABLAB) production, showed that yeast selected for NABLABs biochemically reduce wort aldehydes associated with worty and stale aromas, thereby greatly reducing these off-aromas (“An In-Depth Comparative Study between Commercial Alternative Brewing Yeasts in Low-Alcohol and Alcohol-Free Beer Production,” ASBC Meeting Abstracts, 2023).

I recently tasted three NA (non-alcoholic) experimental beers brewed at the Fermentis Academy in Lille, France. The control beer was fermented with SafBrew LA-01, a maltose-negative yeast (it doesn’t ferment maltose sugar). The first experimental beer was first kettle-soured with Lactobacillus plantarum before wort boiling and fermentation using the maltose-negative strain. The second experimental beer was produced by adding fruit aromas to the kettle-soured NA. The control beer had a perceptible wortiness, however, both beers that were kettle-soured lacked worty aromas associated with wort aldehydes, demonstrating that lactic acid bacteria also reduce aldehydes.

OK, time to wrap these tidbits of information into something useful. For starters, I am not suggesting that dissolved oxygen is not a problem in beer. Focusing on methods to minimize oxygen pick-up after the start of fermentation are, without argument, important to brewing. Many homebrewers these days have taken an anti-rack position because of concerns about oxidation. I use simple methods, including a carboy fermenter and a keg for my secondary. It’s very easy to fill a keg with sanitizer, blow it out using CO₂, recover the sanitizer for later use in the soon-to-be cleaned carboy, and rack beer from the carboy into the secondary without worrying about oxygen pick-up. I usually cold crash this beer after whatever time at fermentation temperature is required to finish the beer, store for a few days, and rack into another keg for serving. Up until now, minimizing oxygen pick-up has been relatively easy.

For those of us who bottle, there are a few options for filling. My preferred method is using a counter-pressure filler, even when my plan is to bottle-condition, because these fillers allow for beer containing CO₂ to be filled with minimal foaming, intentionally foamed or fobbed after filling to push gas out of the headspace, and then capped with minimal oxygen pick-up. Commercially available bottle-conditioned beers are usually filled with about 2.2 volumes of CO₂ so that fobbing before capping is possible. High package airs occur when this step of the filling process is not properly performed. This is where homebrewers tend to deviate from commercial norms.

Most homebrewers use something like a BeerGun® or a flexible hose that can be pinched to stop flow to fill bottles with still beer from a carboy, bottling bucket, or Corny keg. Still beer contains too little CO₂ to fob and always leaves headspace gas, which is 20% oxygen, in the top of the bottle. While it’s tempting to leave minimal headspace in the bottle, that trick often results in bottle breakage. We’re now back to the beginning of this story where bottled craft beer in the early 90s often had very high package airs. I drank my fair share of great microbrewed beer back in that time and enjoyed more fresh beer than oxidized beer. The game changed as more beers started to show up on warm shelves, in places further and further from the brewery, and sat for longer and longer time periods. You can control this at home.

The other thing homebrewers without sophisticated bottle fillers can do is dose fresh yeast with priming sugar before packaging. Fresh yeast will not only carbonate your beer faster than whatever happens to be hanging around after fermentation and aging, but it will be in a better metabolic state to reduce staling aldehydes that develop as oxygen reacts with alcohols. Most bottle-conditioned beers contain about 500,000 yeast cells per mL, roughly 10–20 times less than wort pitch rates, and brewers wanting to dose fresh yeast need not go overboard. This last bit is the key that recent research explains; active yeast converts staling aldehydes back to the compounds, primarily alcohols, they were prior to oxidation like an oxidation eraser. Thanks for the great question that led me to some interesting references!

A homebrewer’s best friend

For every passionate homebrewer, the joy of crafting the perfect beer is often accompanied by the less glamorous task of cleaning and sanitizing our equipment. In particular, kegs can be a challenge to clean thoroughly, especially if they’ve housed a particularly hoppy or yeasty brew. Enter the DIY keg washer, a game changer for homebrewers looking to streamline their cleaning process without breaking the bank.

Keg washing is crucial for ensuring the purity and taste of your beer. Residual yeast, hops, or even small particles can influence the flavor of subsequent batches, leading to inconsistent results. While commercial keg washers are available, they can be prohibitively expensive for the average homebrewer. Moreover, in regions outside of North America, these specialized tools are hard to come by. This is where the ingenuity of the DIY spirit shines.

Creating your own keg washer using a domestic pump, PVC tubes, John Guest connectors, and a zip ball is not only cost-effective but also surprisingly simple. The pump serves as the heart of the system, providing the necessary pressure to circulate cleaning and sanitizing solutions through the keg. PVC tubes, known for their durability and resistance to chemicals, are ideal for directing the flow of these solutions. The CIP (Clean-in-Place) spray ball, a versatile cleaning tool, acts as a scrubber, ensuring every nook and cranny of the keg is reached.

The assembly process is straightforward. Connect the PVC tubes to the domestic pump, ensuring a tight fit to prevent leaks. The other end of the tube should be fitted with the zip ball, which will be inserted into the keg. 

The CIP (Clean-in-Place) spray ball, a versatile cleaning tool, acts as a scrubber ensuring every nook and cranny of the keg is reached.

One of the primary challenges in designing this DIY keg washer was ensuring consistent cleaning inside the input and output posts and tubes. The solution? Using two ball locks connected to the main mounting via John Guest connectors allows the pressurized liquid to efficiently clean the parts of both posts.

Once your keg is sparkling clean, the benefits are immediately apparent. Not only will your beer taste fresher and maintain consistent flavor, but you’ll also extend the lifespan of your kegs, preventing corrosion, contamination, and buildup that can compromise their integrity.

A DIY keg washer is an invaluable tool for any homebrewer that uses Corny kegs. It offers an affordable, effective solution to one of brewing’s most tedious tasks. With cleaner kegs, you’re ensuring that each batch of beer is as delicious as the last. So, why not invest a little time and creativity into building a keg washer? Cheers to innovation and the perfect pint!

Tools and Materials

• 3.3 ft. (1 m) 1-in. (25-mm) PVC pipe
• 1-in. (25-mm) PVC coupling with four outlets
• (3) PVC coupling 1-in. (25-mm) to 1-in. (25-mm) female thread
• PVC coupling 1-in. (25-mm) to 1¼-in. (32-mm) female thread (or whatever size thread the pump has on its outlet)
• (2) PVC coupling 1-in. (25-mm) male thread to ½-in. (13-mm) female thread 
• (2) John Guest connector 3⁄8-in. (9.5-mm) to ½-in. (13-mm) male thread 
• ~4 ft. (1.2 m) 3⁄8-in. (9.5 mm) speedfit tube
• Liquid ball-lock (or pin-lock) connector 
• Gas ball-lock (or pin-lock) connector
• Submersible pump
• CIP (Clean-in-Place) spray ball with 1-in. (25-mm) male thread 
• 1-in. (25-mm) PVC coupling T
• 1-in. (25-mm) PVC end cap
• (4) 1-in. (25-mm) PVC elbow coupling
• PVC adhesive
• (2) 3-D printed pieces (optional)

Step by Step

1. Cutting Out the PVC

Begin by cutting the 1-in. (25-mm) PVC tube to the following measurements: (1) 82⁄3-in. (220-mm), (2) 61⁄3-in. (160-mm), (1) 4¾-in. (120-mm), (1) 3-in. (75-mm), (2) 1½-in. (40-mm), and (2) 1-in. (25-mm) sections. Sand the ends to ensure a smoother surface, which will enhance the adhesive grip when gluing.

2. Build the Spray Wand

Assemble the PVC tubes and couplings as illustrated in the diagram. You will be using the following cut PVC pieces: (1) 82⁄3-in. (220-mm), (1) 3-in. (75-mm), and the (2) 1-in. (25-mm) sections to create the spray wand. These will be fit into the PVC coupling with four outlets. Ensure you use a specialized PVC adhesive to bond the pieces together as these pipes will be pressurized. Use the couplings to transition to threads. Apply plumber’s tape to the threaded sections to prevent any water pressure-induced leaks. Affix the spray ball to the top of the assembly.

3. Attach Pump To the Wand

Attach the spray wand assembly to the submersible pump. It’s crucial to ensure this connection is tight; otherwise, the assembly might not receive adequate pressure. Again, use plumber’s tape to ensure no leakage from this connection.

4. Give It Wings

Install the John Guest connectors, the tubes, and the ball-lock connectors. These will be attached to the keg’s two posts to ensure the keg inlet and outlet are fully cleaned and sanitized. Ensure the tubing is long enough to facilitate easy connections to the posts.

5. Build the Support Stand

Using the same PVC adhesive, set up the separate keg support stand as depicted. You will be utilizing the remaining PVC cuts for this step. The leg section needs to be cut to size since it, along with the endcap and T sections, needs to match the height of the pump, which will serve as the stand’s other leg. For an optional enhancement, consider 3-D printing the two plastic components that will rest on the spray wand wings and further stabilize this support. The link for the .stl print file is found here.

6. Test Run

Submerge the entire assembly in a bucket filled with hot water and a detergent like PBW or similar. Connect the ball locks to the keg, position the keg downward, and activate the pump. Let the magic begin! I always run for 15 minutes for cleaning, then a quick 3-minute cycle for sanitizing.

Pumping Up the Volumes

Let’s start today with a hardware discussion. When discussing pushing beer from a keg into your glass, the gas regulator is an important element and brewers should know how they work and how to maintain them. These work horses are all around us and if you are like most normal people (meaning not an obsessed homebrewer) you might not think twice about the gas regulators in your life. The regulator in your gas stove. Water heater. Furnace. Grill. Kegerator. But of course, we are not like most people as we are homebrewers and we are afflicted with the need to figure stuff out and maybe occasionally fix stuff. How the heck does this regulator contraption work anyway? Let’s find out. We will also discuss carbon dioxide gas (CO₂), nitrogen gas (N₂), and the cool stuff that happens when you combine the two (beer gas). Pour yourself a cold one. Think about the fine job your regulator is doing. Let’s dive in.

A properly functioning gas regulator has one job. That is to regulate the flow of gas from within the gas cylinder. How this is accomplished is not at all complex either. The basic explanation is a gas regulator controls the flow of gas from the supply to the receiver via a mechanically activated valve. Gas from the cylinder enters a chamber through the high-pressure inlet. The gas is unregulated at this stage meaning the pressure within the gas cylinder flows as freely as the diameter of the inlet size will allow. These gas molecules are at delivery pressure (high) and collect within the sealed body of the regulator (bonnet). Here the high-pressure gas exerts pressure on the diaphragm. The diaphragm in turn is held in position with a calibrated spring assembly. If the force of the spring is equal to the force of the inlet gas, the gas in the bonnet is stabilized and nothing much happens. If the gas pressure overcomes the resistance of the spring pressure, the diaphragm opens a crack within the bonnet, allowing the gas molecules to pass through and on to the low-pressure outlet. Gas is free to flow into a keg or into atmosphere. If the gas is going to the keg, eventually the closed system will equilibrate with the spring force within the bonnet and the diaphragm will close, stopping the flow of gas. This description is simplified, but not by much. 

Not All Gas Regulators are Created Equally

There are many varieties of gas regulators. Of course, we are not discussing the regulator on a natural gas pipeline here, so no real need to elaborate. Draft system regulators do come in a variety of price points, however, and there are some design choices made between the lower and higher price varieties. Be aware that the differences are not great between the mid- and high-end range. A middle of the road regulator from a name brand company is all that is required. No name junk is just that. Avoid it. High-priced commercial units work great, but so do mid-range units. You’ll get more shiny metal bits and a solid dial to turn, along with some improved internal guts. But not enough to warrant the price tag. Expect to pay $50 for a decent regulator and up to $100 for the “Pro” variety (I run a draft install company, and therefore am a professional, and we do not buy “Pro” regulators. The cost/benefit just doesn’t work out). There are many ways to spend too much money in this hobby of ours. Get a name brand regulator and you’re good in my opinion. Use that saved money on fancy glassware or maybe fancy yeast.

A trade secret is that you will not be using a rebuild kit if your regulator fails. Go ahead and try. We have. If you want to spend a few hours pulling your hair out trying to get all the bits and small parts seated just right, numerous times, go for it. Save your money and ask me how I know. 

You cannot accidentally thread a CO₂ regulator onto an N₂ tank, nor can you attach a nitrogen regulator to a CO₂ tank. The male-to-female threads are opposite. A CO₂ tank threads onto a male-threaded CO₂ regulator and vice versa. I mention this because you may see thread adapters that are available to adapt tanks and regulators. My word of caution is to avoid conversion kits. Nitrogen bonnets are steel, but do not dial in CO₂ pressure accurately. The bonnets of a CO₂ regulator are plastic and will not tolerate the high pressure of a nitrogen cylinder. 

Regulators Are A One-Way Valve

The gas will only flow in one direction. Despite this fact, many times brewers think by lowering the applied pressure they can lower the carbonation of the keg beer. Or maybe they don’t think that at all? If you apply too much pressure to your keg, there is only one way to correct the problem. Turn off the gas, either at the valve or by turning the round handle on the gas cylinder completely off (counterclockwise). Pull the Cornelius keg or Sanke coupler pressure relief valve (PRV) until enough gas is removed. Then reapply gas pressure to the correct volume. If not carbonated to the desired amount, you’ll need to get the excess gas out of solution. Shake the keg, pull the PRV and wait 20 minutes. Do this procedure until you feel like you have achieved beer flatness. Now work back up to the correct applied pressure. Getting the pressure perfectly dialed requires a bit of skill and patience.

When discussing pushing beer from a keg into your glass, the gas regulator is an important element and brewers should know how they work and how to maintain them.

Recall that the diaphragm opens when the spring pressure is less than the tank pressure. As the two forces get closer to equal, the gap will get smaller and smaller until it closes entirely. The needle on the gauge will rise quickly, then slowly creep as it approaches your set point. The tendency is to overshoot the desired pressure because we don’t see the needle immediately landing where we want it to. Give it a few minutes to creep into place and if you are still low, then dial in a tiny increase in pressure. If you do overshoot your target, go back to venting gas. Unfortunately, when venting keg gas you are also venting beer aroma. This is a particular concern with a brew that you tirelessly slaved over, trying to get every bit of hop aroma you could muster.

Gas Cylinders Are High Pressure 

There are some legitimate safety concerns with gas cylinders. Respect that a tank of CO₂ gas is at around 860 PSI (5,930 kPa) and a tank of nitrogen is closer to 2,200 PSI (15,170 kPa) at ambient temperature. Neither gas is flammable. In fact, atmospheric air is about 78% nitrogen and CO₂ is an effective fire suppressant. However, if a cylinder of compressed gas falls and the regulator snaps off, you are dealing with a rocket of gas molecules. This is not theoretical either, as there are documented injuries. Fire code typically requires chaining the cylinder securely to a wall. Consider doing the same in your home. Nothing will get your attention faster than the sound of high-pressure gas blowing out. Not fun!

Gauges Lie To Your Face

The gauges on your regulator cost about $5 each. They work as well as any $5 piece of mechanical equipment could be expected to work, which is just good enough. A relatively cheap upgrade here is to replace the gauges with higher quality units. For a few bucks you can thread any ¼” NPT gas gauge to your regulator. A worthwhile addition is to install a digital gauge that is much more accurate, particularly at the relatively low pressure we use in homebrewing. 

Another important area to mention is the difference between gauge pressure and absolute pressure. Atmospheric pressure changes based on elevation and brewers need to understand that gas expands at different levels based on that discrepancy. 5 grams of carbon dioxide expands to 3.58 L at 8,000 ft. (2,438 m), compared to only 2.58 L at sea level. This is why beer served on an airplane may seem overly carbonated. When carbonated beer changes elevation, this absolute pressure delta may wreck havoc on the carbonation level.

When it comes to gauge accuracy CO₂ regulators are normally described as Grade B, 3-2-3. The numbers represent the +/- percent accuracy across the dial with the first number representing the first third, the second the middle, and the final number the last third. A 30-PSI gauge in the 0 to 10 PSI range and the 20 to 30 PSI range is therefore accurate within +/- 0.3 PSI (0.002 MPa). That is pretty good, to be sure. The 30-PSI gauge is the sweet spot. You have enough range to force carbonate at high pressure, but the dial is reasonable for dispense pressure. A gauge that goes to 120 PSI or more is going to be awfully hard to precisely dial in to your dispense pressure. You may see these regulators; they are meant for soda or seltzer. The regulator body will be made of steel and not plastic though, so if you get one and replace the gauge, perfect. It’s still hard to dial in 12 PSI with a regulator designed to dispense at 80 PSI. The slightest turn of the dial results in a big jump in delivery pressure because the spring is quite stiff.

What about that other gauge on your regulator? You have a low-pressure gauge that is telling you the amount of pressure being supplied to your keg (the right-hand gauge). You also have a high-pressure gauge, which is telling you the pressure in the tank. First, if the needle is not in the red, you still have CO₂ gas. Second, if the needle is in the red or below, your tank is about to run out or already empty. The high-pressure gauge only really tells you what you already know . . . you are out of gas. Why? Because the carbon dioxide in the tank is in liquid form since CO₂ gas liquefies at a relatively low pressure-temperature intersection. Not unlike your propane tank, as long as there is liquid CO₂ available, there is gaseous CO₂ available. If there is liquid CO₂ in the tank, the pressure on the high gauge will be steady, only varying with changes in temperature. Near zero indicates the liquid has boiled off and your draft system is literally running on fumes. Weight is a better method of estimating tank levels with CO₂ so long as you know the tare weight of the tank. 

The exception to this is a tank of nitrogen, which is not liquid when under pressure. That high-pressure gauge is indeed a good indicator of remaining gas molecules within the tank. The needle moves towards zero as the tank empties. 

Knowing Your Volumes

If you are a brewer that adheres to style guideline, an important consideration is getting the volumes correct for the style. Anywhere from 2.2 to 3.0 v/v is typical. Volumes are an important part of brewing but not part of the rabbit hole of today’s discussion. When speaking to commercial brewers, I mention that hitting your target carbonation level is important and very few among us can realistically notice a difference of a tenth of a point or two. Personally, I have many targets to hit in my homebrewing and dead accurate volumes is not super high on the list. Point being, consistency is probably more important than precision. Knowing what we know about gauge accuracy, an exercise in precise volumes might be futile anyway.

Do You Need Nitrogen Gas?

Most of us (probably) do not need nitrogen gas and I am (almost) sure of it, too. Do you have a long-draw system, with trunk line and remote faucets? If not, you do not need nitrogen. Do you want to serve nitrogenated beers like an Irish stout? If not, you do not need nitrogen. But for those that answer yes to either of those scenarios you will need a nitrogen tank, regulator for it, and a stout faucet if you plan to pour nitrogenated beer. But word of caution: If you are using anything other than 100% carbon dioxide, you are making your life more difficult than needed. It’s the reality of it.

As noted, nitrogen is useful in two applications. It is essential for nitrogenated stouts (aka Guinness style) or any nitrogenated style for that matter. Nitrogen is also needed for many long-draw systems where increased pressure is required to balance the system. The sort of draft beer system where the kegs are 30 feet (9.1 m) or more from the faucets or in the basement and faucets are upstairs. The nitrogen is used to overcome system resistance and gravity without over carbonating the beer. If you are interested in the anatomy of a long-draw system, it can be found here: byo.com/article/long-draw-draft-system/

Once again, do you need nitrogen? Of course you do! The magic of nitrogen allows you to dispense magic nitro stouts and other fun styles. The magic of nitrogen allows you to design and install a long-draw system. The magic of nitrogen affords you the opportunity to experiment with all sorts of fancy whiz bang contraptions you did not even know you needed. Nitrogen is great and because you are a homebrewer who loves to tinker with new things, you’re going to agree. 

Nitrogen gas exhibits some important qualities that differ from carbon dioxide. Importantly, nitrogen is about 80 times less soluble in water (beer) than CO₂. This means that if you need to apply 30 PSI of pressure to your beer, the nitrogen will (mostly) not dissolve into the liquid (and the little that gets dissolved does wonderful things to the texture and foam of the beer). The reason for this poor solubility is that the oxygen ends of a CO₂ molecule have a slight negative charge. Water molecules are attracted to these polar areas, allowing CO₂ to dissolve in water. Carbon dioxide is the outlier among gases in this quality. The beauty of brewing is that these chemical reactions do not occur because of brewing but are beneficial nonetheless. 

Fun fact #1! Carbon dioxide gas, when dissolved in beer, becomes carbonic acid. I believe CO₂ is the underappreciated fifth ingredient in beer. Water, malt, and hops are famously in the German beer purity law (the Reinheitsgebot we know and love). Later, yeast was included. Is it time to add carbon dioxide? The carbonic acid is an essential counter to malt sweetness and enhances hop bitterness as well. Flat beer is simply sweet and often unpleasant. Nitrogen, being inert, does not offer any acidity. The sweetness of the malt shines through. Hop bitterness does not have any crutch to help do the job. I think many of us have had that morning small pint, poured the night before. The beer that has gone flat. We discover that a), warm beer is miserable and b), flat beer is oddly sweet. I digress.

Let’s hypothesize that your draft system needs 30 PSI of pressure to overcome gravity, resistance, or both. 30 PSI of CO₂ is going to give you 4.25 volumes at 38 °F (3 °C). Way too much. Let’s substitute nitrogen gas for part of that carbon dioxide. With 70% carbon dioxide and 30% nitrogen (aka 70/30 blend), the keg is only receiving a portion of CO₂ molecules, and as a result is also achieving 2.96 volumes at 38 °F (3.3 °C). The 30 PSI of pressure still exists though and, with nitrogen being insoluble, we achieve quite a bit of push to overcome our system’s design constraints. We can have our beer and eat it too. Some common blends are 70/30, 60/40 and 25/75, with the first number being the percent CO₂ present in the blend. These three blends are basically all the blends we will ever encounter, though we can also get special order blends for lightly carbonated white wines, for example. With blend gas, we can dial in system resistance to match our applied pressure, while still maintaining the appropriate volumes. The 25/75 blend can be found packaged at your gas supplier. This blend was popularized by Guinness and it works well for that application. 

As an aside, sometimes we encounter 25/75 in commercial systems that do not need it. The 25/75 blend will pour great but all the other beers (other than than those meant to be nitrogenated) lose carbonation from day one. Guinness (and most all nitro stouts for that matter), is carbonated to about 1.2 volumes, which we know is less than half a typical ale. All other beers on 25/75 blend lose carbonation until they are equilibrated to around 1.2 volumes, more or less, at standard serving settings. If your gas cylinder is 25/75 with anything other than your nitro dispensed beer, you are also wasting money as it is expensive too. 

How Do I Get Magic Gas Blends In My Brewery?

After you have determined that you do in fact want nitrogen gas and blended gas, you have a few options. For nitrogenated beer (Guinness style) you can buy pre-mixed bottles of 25/75 (aka Guinness gas or simply beer gas). Any gas supplier will have this blend readily available but be sure to double check you are getting the specified blend.

If you are designing a long-draw system and 60/40 works, things get a bit more complex and a bit more expensive. First, do what you can with your design to get to 70/30, as this blend is usually a better choice that will hit the sweet spot of carbonation and push better than 60/40, but this is dependent on the system and its requirements. Next, look into McDantim gas blenders. A gas blender is just that. One line of CO₂ gas and one line of N₂ gas go into the blender. Blended gas (either 60/40, 70/30, or 25/75 depending on model you purchase) comes out. A gas blender is accurate and useful, but the costs can be steep for a homebrewer. Expect to pay between $800 and $1,500 for your blender. Also know that regardless of the brand you choose, all gas blenders are made by McDantim. Buy the best deal you find from a trustworthy vendor. Blenders are expensive, but also bullet proof and dead-on accurate. 

What about pre-mixed bottles of blended gas? Unfortunately, as we get away from the 25/75 mix, things get squirrely. Nitrogen and carbon dioxide do not co-exist peacefully in one tank. Think oil and water. The two different molecules do not occupy space evenly, and the result is uneven delivery of gas. Let’s go back to high school physics for a moment. All gas has both a critical temperature and a critical pressure. The critical temperature of a gas is the point where the gas is liquified under pressure. Above the critical temperature, the gas will not liquify, no matter how much pressure is applied. 

The critical pressure is the point where gas becomes liquid, provided that the critical temperature is not exceeded. Carbon dioxide and nitrogen have different curves. Liquefying CO₂ is not too difficult to achieve, because the critical temperature is 88 °F (31 °C). The critical temperature of nitrogen is -232 °F (-148 °C), and that is not something that can be achieved without an unrealistic investment. Liquifying N₂ is realistically not a thing. If both gases are filled into a cylinder and we want to maintain a specific blend, we cannot exceed the critical pressure of CO₂, because once the CO₂ becomes liquid, the desired ratio is not going to be maintained. Fun fact #2! Because a tank full of nitrogen is entirely gas and not liquid, there are significantly less nitrogen molecules in the tank, and the tank runs out pretty quickly. But as stated earlier, the high-pressure gauge is a good indicator of remaining nitrogen in the tank.

I hope this helps explain some regulator and beer gas mysteries. Now back to brewing beer.

Q: I recently bought a Lukr faucet for my kegerator and it works well, but I want to optimize my installation. There isn’t much information on the web. I want to know the best carbonation level for my beer, the type of pours possible, and how to achieve these without excessive foam.
— Michael Bilodeau • Saguenay, Quebec

A: Lukr beer faucets, often referred to as “Lukrs,” have been popping up all over North America in recent years due to the rising popularity of traditional Pilsners and other lagers by beer-loving brewers. As a traditionalist, this is a welcome trend and refreshing juxtaposition to slushy beers dispensed from frozen drink machines. Lukrs are a type of plug valve used to start and stop beer flow from a pressurized keg or an atmospherically dispensed cask. This is the same type of equipment that was traditionally used to tap a barrel before pouring. Many beer lovers know that the Mayor of Munich kicks off Oktoberfest each year by ceremoniously tapping a keg barrel of fest beer with an old-style tap and a wooden mallet.

Lukr faucets are made in the Czech Republic and are pretty much “the” beer faucet seen around the best Pilsner bars in the Czech Republic. Most are used to dispense beer from pressurized large serving tanks (500–1,500 liter stainless tanks, housing a polymeric bladder that is squeezed with gas pressure), conventional kegs, and, less frequently, from pitch-lined wooden barrels. When used to pour beer from bladder tanks or kegs, the system must be properly balanced by the draft line like any other beer faucets. And when used to pour beer from a barrel, the pressure in the barrel is usually relieved by driving a spile into the barrel as a vent; in these installations the only pressure at the tap comes from the hydrostatic head of the beer (gravity).

Unlike most faucets, Lukrs are equipped with a mesh screen and a beer nozzle at the business end of the faucet. The mesh screen helps to make a creamy foam when the valve is partially opened and the nozzle directs the stream of beer and liberated carbon dioxide into the glass. Some users remove the mesh screen to make the Lukr faucet more like a conventional faucet. As a foam lover, removing the screen makes no sense to me because it serves a specific function when
pouring beer.

Let’s pause here and address your question about carbonation level. Any beer that can be poured from a standard beer faucet can be dispensed through a Lukr. The key to dispensing draft beer from any faucet is line balance. Many years ago, I worked on a project for a large sparkling wine producer who wanted to explore serving their products on tap for the turn-of-the-century millennium celebrations. Although this company did not end up building special draft systems for sparkling wine, as was the initial plan, I was able to serve sparkling wine from a beer tap with comparable appearance and sparkling sensation to sparkling wine poured from the bottle. I used an old-style Guinness faucet with a flow control knob (not actually used for flow control but that’s a different topic) and the trick was an extremely long choker. Not rocket science, but pretty darn cool! When pouring your beer through a Lukr faucet, the best dispense pressure is the pressure that goes along with your beer. No real restrictions on your beer’s carbonation level.

I stated earlier that Lukrs are plug valves. A plug valve consists of a straight-bored plug that rotates through the valve body. When the hole in the plug is oriented 90˚ to the direction of flow, there is no flow. When the faucet is opened by turning the handle a quarter turn or 90˚, the plug rotates and opens over a variable range. 

Although plug valves are often used as simple on/off valves, they are also good control valves because flow rate through these valves is roughly linear with the valve’s position. An interesting thing about control valves, including plugs, is that they cause liquid turbulence when the valve is not 100% open. And it’s the liquid turbulence and associated pressure drop across the valve when partially opened that helps create foam when beer flows through a Lukr. If Lukr faucets have a superpower, it’s this sometimes-present turbulence and the ease of adjusting and maintaining the position of the valve plug when pouring.

This brings me to another pause; pour types. Lukrs can be used like other faucets to quickly pour a beer. A healthy shot of foam into your glass followed by a “clean” pour, achieved by completely opening the tap and pouring down the side of a glass and under the foam, results in the classic hladinka pour with a beautiful, creamy, collar of foam sitting atop of a full pour of beer. For ordinary beer enjoyment, this is my preferred pour.

The Czechs also have an “ordinary” pour named the čochtan, described on beer sites as a neat or British pour, which was surely created for tourists suspicious of beer foam since in their experience the foam is only a thin layer that sits atop the beer. In my humble opinion, as a lover of great beer and speaker of the beer truth, this style of pouring appeals to penny-pinchers more than it does to palate-smackers. My advice . . . nothing to see here!

Moving onto to a foamier pour, beer containing about 2⁄3 foam and about 1⁄3 beer is called a šnyt or a schnitt in German. The story about this pour is that is often the last beer of the night and is sold at a discounted price because the šnyt pour does not contain nearly as much beer as a regular pour. To pour this using a Lukr faucet, tilt your glass 45˚, open the tap halfway until your glass is about 2⁄3 full of foam, and then fully open the tap and pour under the foam. The šnyt pour knocks carbon dioxide from the beer, creates lots of creaminess to chew on, and minimizes the bloating a beer drinker may get from drinking fully carbonated beer. Depending on the circumstances and the steadiness of the consumer when ordering, beertenders may elect to partially fill a glass, but the ratio of foam-to-beer remains the same. If you order a šnyt and only receive a small pour, it’s because the beertenders gives a schnitt about you!

Finally, there is the legendary mlíko pour. Mlíkos are creamy on the palate from start to finish, look like milk because so little liquid beer drains from the luscious foam, and are often quickly consumed after a meal like a big shot. Who needs milkshake beers dosed up with lactose and vanilla when the mlíko pour is just a crack of the faucet away!

There are a few details to mention about Lukr taps and how they are used. For starters, standard practice is to submerge the beer nozzle under the foam when pouring. You asked about how to minimize foam and this is how it’s done. Pouring beer into foam leads to more foam because bubbles are nucleation sites for more bubbles. Pouring under the foam allows better control of the ratio of beer-to-foam in the glass and minimizes waste. 

Glass selection is also a major part of this control and is one reason why 0.5-liter mugs are the glass of choice when pouring beer from a Lukr. Dipping a beer faucet into a glass while pouring is a total faux pas in many countries because of concerns about cross-contamination, but this technique serves a very practical role. This means that using clean glasses for each pour is mandatory to prevent contaminating the beer faucet from unwashed glassware. If you want to host a party and serve your beer from a Lukr, you need to be prepared to wash glasses and manage the cleanliness of the faucet. Yet another reason beer lovers are adamant about clean glassware.

One last technical detail to cover is the purpose of the tap screen. Although everything I have read about Lukrs state as fact that the screen aerates beer, I disagree. The design of the Lukr faucet does not pull air into the beer stream and the term “aerate” is a misuse of the term. The tap screen does serve an important foaming role when the faucet is partially opened, but it’s not to pull air into the beer; Pilsner beer has plenty of carbon dioxide to provide all the gas needed for beautiful foam. 

Lukr does sell a stout “aeration plate” (another misuse of this term) and a “stout nozzle” insert, actually a restrictor plate and a flow straightener in the parlance of Guinness, for their faucets so that nitro beers can be served by simply swapping out the tap screen and inserti

Heads-Up Display

Keg management is an important tool in any kegging brewer’s arsenal. Being able to keep track of keg levels is vital to brew scheduling and not being surprised at your summer BBQ when the keg kicks unexpectedly. Until recently, I’ve been using the method of when you pull the tap handle and beer comes out, that means there’s still beer in the keg. When no beer comes out, the keg is empty.

There is a small variety of DIY and commercially available systems out there. In-line flow meters, the ol’ ball and magnet thing, pull the keg out to room temperature and let it sit for a few minutes until it sweats at the level line. The one I liked the most is the Plaato system that came out not too long ago. I really like the idea of the Plaato system because it uses a scale to very closely approximate the remaining beer in the keg. I just couldn’t pull the trigger on the $130 per scale price tag, and I need three, so I found that be a little cost prohibitive. After some more research, I ran across a YouTube video of a guy who made a scale out of a piece of plywood and some electronics on the cheap. Not just a little cheap. I mean cheap, cheap. I was intrigued . . .

Some more internet research and I found someone else who used the same materials, but upped the game by 3-D printing a housing and added LEDs to it. My only problem with his design is that the diameter was wider than a corny keg and definitely too wide for my 3-D printer. I have a standard-sized kegerator and the kegs fit in there snugly as it is. So, it was high time to design my own. I used Google SketchUp to bring this to life.

I was able to design a scale that was the exact diameter of a corny keg and only lifted it about an inch (2.5 cm) off the bottom of the kegerator.

I was able to design a scale that was the exact diameter of a corny keg and only lifted it about an inch (2.5 cm)off the bottom of the kegerator. It’s a little tighter up top, but not impossible to connect gas and liquid lines. 

After the design was finalized and the proof of concept was there, I decided to go for it. The price point was right for me too. At less than $10 per scale for the boards, Home Assistant being free and open sourced, add-ons not costing a cent, plus I had some USB cables in the infamous box of extra cables . . . it was worth a shot to see if I could do it. 

This scale can be used in kegerators, keezers, fridges, and it doesn’t have to stop at kegs. You can even use it to monitor CO₂ tank levels or anything up to 110 lbs. (50 kg) that will fit on the scale.

This project is going to be relatively easy if you have experience with Home Assistant, are an avid tinkerer, or are just a good old-fashioned tech nerd like me.

Links:

• Home Assistant: https://www.home-assistant.io/
• ESPHome: https://esphome.io/index.html
• Scale print: https://www.thingiverse.com/thing:6007574
• HX711: found on www.amazon.com
• ESP3266: found on www.amazon.com

Tools and Materials

• 3-D printer (with minimum 235 mm x 235 mm build plate) 
• Printer filament (172 meters / 511 g per scale)
• (4) M4 x 0.7 x 12 mm screws
• M4 x 0.7 tap
• HX711 load cell amplifier (with four load cells)
• ESP8266 (USB-C)
• USB to USB-C cable
• USB power brick
• Soldering iron
• A computer running Home Assistant

Steps

1. Print Scale Housing

I took certain design aspects of those that I saw online and modeled one to suit my needs. Along with the housing, I also made feet and retaining clips to keep the load cells in place. The only glue that is needed is when assembling the feet through the bottom plate and securing the circuit boards. The load cells are kept in place with friction and some clips for extra insurance.

After I had a prototype I was happy with (Figure below), I printed the first production scale using PLA with 70% infill.

2. Boards and Wiring

Wiring is pretty straightforward and there are tons of diagrams, forums, and pages on how to wire the boards around the internet. An important thing to note is that some of the wires on the boards can be wired to different D pins, but if you are doing more than one scale, it’s important to wire them all the same for continuity.

These boards are small — a magnifying glass and a steady hand are key here. Cut to size, strip, then solder the wires to the board per the diagram on the right (Figure below) and solder the black and white load cell wires to each other per the Wheatstone circuit (Image below). The solder doesn’t have to be pretty. It just needs to keep the wires in place and make sure you don’t have the solder pools touch one another. Electrical tape or heat shrink tubing will keep the connections safe and secure.

Tip: I used my prototype 3-D print to hold the load cells and boards while the production print was going.

3. Assembly

After all the pieces are printed and the soldering done, it’s time to do some assembly. Start by tapping the screw bosses with the M4 x 0.7 tap. Putting a piece of tape on the tap threads can act like a depth-stop so you don’t go too far.

Next, glue the feet together through the bottom of the scale. The smaller part of the foot should be on the inside and the larger foot should be on the outside. The outside has the countersinks for the screws.

Then place your load cells in their respective housings following the same Wheatstone bridge that you assembled them in followed by the retainer rings – these are just friction fit. Use some tape or hot glue to manage the wires and fix the circuit boards in place.

Lastly, you will need a hole or slot for your USB cable (Image below). A drill or Dremel will make quick work of this part. Finish it with a file and/or blade to refine the fit, if needed. Affix the top and bottom with the four screws and you have a fully assembled scale!

4. Home Assistant

I am using Home Assistant with the ESPHome add-on to do all the configuring for my load cells. I had an old Intel NUC lying around so I figured I can run Home Assistant on that. You can choose to run it on a stand-alone computer, as a virtual machine, or on a purpose-built Raspberry Pi. Whichever one you choose depends on your setup and needs. Please see the Home Assistant webpage for more details.

5. ESPHome

Once Home Assistant is installed, install ESPHome from Settings→Add-ons to add your scale to Home Assistant. Plug the scale into the computer running Home Assistant. In ESPHome, choose to install a new device. Follow the prompts to complete the installation.

After the installation completes, click on “Edit” in the scale’s window. Here you will see some default code in yaml. You don’t need to edit this, but you will need to add some of the code to get everything displaying correctly. You can copy the code (Figure below) to set up your sensor at the bottom of the existing code, starting around line 29. Please note the “calibrate linear” data will differ with your keg depending on the tare and full weight. You may also change the “update interval” depending on how often you want the values to update. I find 60 seconds to be good. Enter this code under “captive_portal:” then click “save”, and then “install”. You may have to restart Home Assistant a time or two during the process for the scale to fully install.

Note: If any of your values are negative numbers, it’s likely that you have mis-wired the red wires on the load cells. Go back and double-check the Wheatstone bridge.

6. Display

Displaying your keg level is done with “cards” within Home Assistant. Cards are what make up the dashboard. There are many card options. I chose the gauge in a three-card vertical set. Although there are many ways to display the keg scales from Home Assistant using any network-connected device, I wanted a classy screen on a stand display near my kegerator. You can choose any display method you prefer. Here is how I chose to do mine:
I got an old iPad and installed a kiosk app on it. I set the iPad to never turn off, but set the kiosk app to black the screen after X minutes of inactivity. These settings allow me to just tap the screen when in idle state to see the keg levels.

For my frame, I milled up some scrap cherry to hold the iPad. I used a small CNC router to carve text into the wood to show the tap number and added a little quip at the top. My little CNC router travel is a bit too short to do the whole thing, so I had to break the lettering into segments and route out the opening for the iPad by hand.

In my case, because of the layout and formatting, I had to install the iPad upside down. I wanted to limit the times I would have to remove the iPad, so I drilled a small hole in the ‘r’ so I can easily press the ‘home’ button with a finish nail whenever needed.