Troubleshooting draft problems: A guide for bartenders
The following article was published on May 14th, 2014. It has been reviewed and updated as necessary by the ProBrewer editorial staff. For additional sources see Interpreting Foam Problems with UC Davis’ Charlie Bamforth and in the ProBrewer Discussion Boards Problem with dispensing from serving tanks, Dispensing System Advice & Just foam when dispensing from kegs
by John Kater
In the bar business draft problems often develop when the house is packed and there is absolutely no possibility of reaching the one or two staff draft experts. The best way to tackle draft problems is to be prepared. It is prudent to create a troubleshooting guide to your draft system and educate your staff in the basics of dealing with draft beer. A guide can be a helpful training aid as well as a critical reference manual for answering mechanical questions and enabling other staff to temporarily repair the system until your draft expert is available.
Carbon dioxide is a critical component of beer. The lovely, lacy head; the tingle on the tongue; the sound of the bubbles are all integral to the enjoyment of beer. Maintaining the carbon dioxide at the desired level is crucial to a draft dispense system. To understand how to keep this balance, a basic knowledge of the factors that affect carbonation is necessary.
A brewer, when asked about draft line problems such as excessive foaming, will start talking about “universal gas laws” and reciting formulas such as “pressure times volume is proportional to temperature.” The standard reaction to this type of comment is a glazing of the eyes and a slow nodding of the head until 25 minutes later when the brewers gets to the part where he says “turn the regulator down to 12 PSI and vent the excess pressure from the keg,” at which point the nodding and glazing are replaced by an under-the-breath mumbling of, “Why didn’t you just say so?”
Understanding carbonation comes down to a matter of a few simple concepts in chemistry and physics.
• The colder the beer is, the more carbon dioxide it can dissolve. The opposite is demonstrated by opening a warm beer and watching it fob all over the place.
• The higher the pressure in the dispense container, the more carbon dioxide will dissolve in the beer. Common sense; if you want to fit more in there, push harder.
• The smoother the surface in contact with the beer, the more likely the carbon dioxide will stay in the beer. Take two glasses. Sand the inside of one with 100 grit (fairly coarse) sandpaper. Pour beer into both. Which one foams up more? What is happening is that dissolved carbon dioxide needs a rough spot called a nucleation site to form a bubble. Clean beer lines and beer-clean glasses have fewer nucleation sites and therefore keep the carbon dioxide dissolved in the beer, where it belongs.
• Mechanical agitation can cause carbon dioxide to come out of solution. If you tap a keg right after it is delivered, the first few pints will be foamy, just like beer from a shaken can.
• Cellar pressure changes take time to take effect. These basic concepts will help you understand the problems that occur with a draft beer dispense system. But it’s also helpful to know what the ideal properties are.
How much fizz?
The proper level of carbonation, in addition to its sensory augmentation of a beer, is critical to a good pour. Brewers measure carbonation as volumes of carbon dioxide. If a beer has two volumes of carbon dioxide, this simply means that if all of the carbon dioxide were removed from a beer at 68° F (room temperature) at sea level under normal atmospheric pressure, the space taken up by the carbon dioxide removed would be twice that of the beer.
An ideal pour is best achieved at 2.55 to 2.65 volumes of dissolved carbon dioxide, although certain beer styles demand carbonation at different levels. A fresh, untapped keg starts with the correct amount of dissolved carbon dioxide. To keep the right amount after tapping, a balance between the temperature of the beer and the pressure of the carbon dioxide must be maintained. It does get more complicated than that, however. If the dispense equipment has been correctly installed, then a certain pressure is necessary to overcome the resistance of the dispense lines and taps. If the pressure is maintained properly, the carbonation level of the beer remains stable. If the pressure is too high, the beer will overcarbonate. If the pressure is too low, the beer loses carbonation.
Common problems and how to solve them
Troubleshooting the problems that can occur is an important part of maintaining a draft system. Start by placing a rinsed, beer-clean glass at a 45° angle under the faucet, open the tap all the way, and…
• No beer is coming out. When troubleshooting, always check the most obvious thing first. Is the keg empty? If it is, you will feel a rush of gas coming from the faucet as gas escapes from the keg through the line. Is the coupler on the keg correctly? Is the carbon dioxide tank connected, is it full, and are the toggle valves open? Is the line frozen?
• Flat, headless beer comes out. The head goes away too quickly or doesn’t form to begin with. Check the regulator gauge for proper setting. Is the beer glass clean? If the head forms, then quickly disappears, the chances are that the glass is to blame. Head on beer is quickly destroyed by oils, so greasy food and lipstick can ruin beer foam. Did you pour properly?
• Foamy, overcarbonated beer comes out. Is the keg empty? Is the regulator set to the proper pressure? Is the keg storage temperature at the proper temperature of 36° to 40° F? Has the keg had time to settle? Did you open the tap all the way? On a long-draw system, is the coolant cold enough? The glycol reservoir for the coolant should stay right around freezing, plus or minus two degrees.
• The beer starts out fine, but then the line “burps.” There is a warm spot, kink, pinhole, soil deposit, or bad seal somewhere between the keg and the faucet. A full keg might be sitting on the hose in the walk-in, crimping the line. Get the lines cleaned. Check insulation and seals.
• The beer doesn’t taste right. Have the lines been cleaned recently? Beer lines should be cleaned at least every three weeks, preferably weekly. Are the glasses beer-clean? Is air being introduced to the beer somewhere?
• The beer is darker than usual or cloudy, and it doesn’t taste right. Clean the lines. Check the expiration date on the keg. Has the keg been tapped for more than three weeks? Is the keg getting warmer than about 45° F during storage?
• There are little black flakes or slimy chunks in the beer. Clean the lines. Clean and maintain the faucets. Don’t panic, though; these flakes and slimy chunks aren’t harmful — just disgusting. Sometimes a line cleaning will loosen deposits that appear in subsequent beers.
• The first few pours of the day are all foam, but then it’s okay. This means that your pressure and temperature are not staying the same. If your beer cooler gets a lot of traffic during the day, the temperature will rise. Your gas regulator is set to give a good pour at the daytime temperature. Overnight the beer dissolves more CO2 because the gas pressure stays the same but the beer gets colder.
If you can limit traffic by storing only kegs in your keg cooler, this will fix the problem. If you can’t do that, try hanging a slatted plastic air-barrier screen in the doorway to minimize cold-air loss. If this isn’t possible, try turning off the valve from the carbon dioxide regulator at night. Just don’t forget to turn it back on in the morning.
• The last third of a keg is foamy. This is the same problem as above. As the beer is replaced by carbon dioxide in the keg, the area of contact between the gas and the beer stays the same, but the volume of beer is smaller. This allows the beer to dissolve the gas more quickly.
When thinking about getting your beer lines cleaned, remember this important rule: Beer lines should be replaced at least every five years. No amount of cleaning or servicing will help lines that are totally shot.
Ideally, beer lines should be cleaned between each keg, and once every three weeks at the minimum. Over time beer will produce mineral and protein deposits in the draft lines. Bacteria and molds can work their way into the lines, and yeast can form colonies as well. The responsibility for line cleaning is ultimately yours, but the distributors, brewers, and even independent contractors might be involved. Line cleaning can be done with several solutions and contraptions. The equipment is available relatively inexpensively through draft suppliers.
One cleaning option is to use a chlorinated alkaline cleaning solution dissolved in hot water as a cleaner and a rinse with baking soda and food coloring dissolved in cold water. This colored baking-soda rinse is ideal because the baking soda provides a buffer between the heavily alkaline cleaner and the acidic beer. The baking soda also helps to remove odors. And it releases carbon dioxide when in contact with beer, which forms a barrier between the beer and the rinse solution and helps purge the solution out of the lines. The food color and salty flavor of the baking soda let you know when the lines have been completely rinsed and you are pouring pure beer again. Just to prove that this isn’t a waste of time, pour a glass of beer before and after line cleaning and compare them. If your lines needed cleaning, you will taste a huge difference. If you’re cleaning them often enough, there shouldn’t be much of a difference.
The faucets should be cleaned at the same time as the lines. You also need to keep a spray bottle filled with either a) your glass sanitizer mixed according to manufacturer’s instructions or b) a solution of one part bleach to nine parts water. As part of your closing ritual, spray out all of the beer faucets with this spray bottle. Doing this will prevent unwanted bacteria, mold, and yeast growth.
Price, presentation, and variety are compelling reasons to sell draft beer over bottles. Remember that draft system problems are generally fixable or preventable with minimal maintenance. Many of these problems are only encountered early and go away when you get your system properly tweaked.
In a clean sink, wash the glasses with a low-foam glass cleaner. Rinse thoroughly with fresh water. Sanitize with the minimum amount of sanitizer required (according to label instructions). Use test strips to ensure the proper level of sanitizer.
Dry the glasses in a way that allows airflow inside the glasses, such as on a drying rack. Finally, rinse the glasses with cold water before filling them with beer.
To be sure if your glasses are beer-clean, check these three indicators:
• Bubbles will not form on the sides of a beer-clean glass.
• Lacing from the head will only form on a beer-clean glass.
• Wet the inside of a glass and place it upside down on the bar. If drops cling to the glass, it isn’t beer-clean.
Pouring the perfect pint
A perfect pint of beer starts with a just-rinsed, beer-clean glass held a half-inch to an inch below the faucet. Tilt the glass 45° and open the faucet all the way, pouring down the side of the glass. When the glass is half full, stand it straight up and continue pouring directly into the center of the glass. Quickly close the faucet, leaving a three-quarter-inch head at the top of the glass. This thick, creamy head should leave lacing on the glass as the beer is enjoyed.
Beer faucets are designed to be opened all the way every time. Opening a faucet only partway makes the flow turbulent, supplying nucleation sites and making the beer fizz up.
Achieving the ideal pour depends on starting with beer from a fresh, cold, properly carbonated keg. The beer must then be pushed by clean, appropriately pressurized carbon dioxide through a coupler with good seals that connects to a smooth, recently cleaned, temperature-stabilized, leak-free line through a clean faucet, and out into a beer-clean glass.
John Kater was brewmaster of the Southside Cellar Brewing Co. in Birmingham, Ala., when this article appeared in BrewPub Magazine.