Beer Basics

Since draft beer isn't pasteurized, it's a living product. In many cases, the yeast used to ferment the beer in the first place continues to work its biochemical magic, albeit more slowly, after the beer goes in the keg. That fermentation process also creates carbonation in the beer. But that natural carbonation can be easily affected. Two of the key factors that impact your ability to pour a good beer behind the bar are temperature and pressure.

Temperature is important. Most brewers recommend that you store beer at 38˚ F or below. Although some operators may store ales and specialty beers at higher temps, most customers here in America like beers as cold as they can get. Temperature also plays a key role in holding beer's natural carbonation in suspension. Too warm, and the carbonation will be released from suspension, causing foam. Too cold, and the beer will tend to come out flat when it's poured.

If you can, store beer in its own walk-in to maintain the proper temperature. Racks make it easier to stack and store kegs. If you must store kegs in an existing shared walk-in, you'll find it harder to hold
temps constant because kitchen employees are in and out a lot for food products. Curtain off the keg area to help hold temperatures.

Pressure is the other major factor that will affect carbonation. Beer's natural carbonation provides some pressure, but you need more to force the beer out of the keg and through the lines to the
tap. Too little pressure and the beer will be flat or will flow too slowly. Too much, and the beer will be foamy and pour too fast.

Different beer styles may require different pressures to maintain a particular level of carbonation. Distance from the keg to the tap also will dictate how much pressure is needed to move the beer through the lines. And the longer the lines, the greater the chance they'll warm up along the way. Depending on all those variables, brewers may recommend pressure from about 12 to 18 PSI.

it's a gas

The most common way to pressurize kegs is with CO2. Because beer is naturally carbonated with CO2, using the same gas to force the beer through the tap's lines makes sense. But there are caveats. As mentioned earlier, using CO2 may work up to a point where you can add sufficient pressure to a keg of beer to provide a good flow to the tap without over-carbonating the beer. Where too much CO2 would be a problem, you need other solutions.

For example, if a brewer recommends a limit of 14 PSI on an ale, you serve for carbonation purposes, but the distance from keg to tap requires 18 PSI, you can blend CO2 with a different, non-carbonating gas. Compressed air would be one option, but the Brewers Association of America says it should never be used. Oxygen can quickly degrade beer, and other contaminants in compressed air also can affect beer's taste and odor. Most systems use nitrogen blended with CO2.

Another problem you may face is long runs, 300' or more. When distance becomes a problem, the best alternative may be a beer pump. Beer pumps operate with CO2 or compressed air, but the gas never contacts the beer. A pump can push beer up to 800' horizontally or 10 stories vertically
through a single line.

For your setup, you'll need CO2 tanks, regulators, and lines. For safety, locate your CO2 tanks outside the walk-in where the kegs are stored. (If a leak occurs, the gas could build up very quickly in the
enclosed space of a walk-in, potentially causing employees to blackout or even die.)

Regulators control the release of CO2 from the tanks at the psi you specify. Tanks may be pressurized up to 1,200 PSI, so regulators are obviously a necessity. Some regulators only come with a single gauge that indicates the pressure being delivered to the keg. Better regulators have two gauges; a high-pressure gauge to indicate the tank's pressure, so you know when the tank is running low, and a low-pressure gauge to monitor PSI to the keg.

Gas lines are typically vinyl with a thicker wall than beverage lines to provide additional strength required to handle high pressure and minimize the transfer of any odors or flavors. Braided vinyl is even stronger for longer runs.

If you are planning to use blended gas, you'll need nitrogen tanks. And in that case, you'll also need a gas blender, a unit that mixes the contents of each tank in preset proportions. This ratio is set by the manufacturer and can't be changed on-site. If you need different blends for different beers, you can get blending units with one, two, or three settings.

down the line

You've got beer, and you've got pressure. Now you need beer lines to transport the beer from keg to tap. Because rising temperature is the biggest contributor to the release of CO2 in beer, it's essential to keep the beer cold on its journey, so dispensing systems run chilled glycol lines alongside the beer lines to keep them cold.

Beer lines are typically 3/8” in diameter, but some suppliers are promoting 5/16” tubing on runs of 30' to 150'. The smaller diameter, they say, simplifies balancing the system and requires less cleaning, which means less waste and less expense. High-quality lines are poly tubing with a special nylon barrier lining that prevents migration of moisture, flavors, and odors.

Glycol lines are typically made from the same type of material (color-coded so you know which line is which). At least one manufacturer offers copper glycol lines that have better heat transfer. Copper, of course, is more expensive, and not as easily routed through twists and turns, and tends to condense and sweat more.

Trunklines are beer lines bundled together with glycol lines. Most dispensing system manufacturers purchase bundles of lines or tubing from other suppliers in combinations depending on the application. Suppliers provide these trunklines in rolls of about 300', and manufacturers cut lengths to fit each installation.

Look for trunklines that bundle beer and glycol lines so that each beer line has direct contact with a glycol line. The bundle should be wrapped with a moisture barrier such as a layer of clear Mylar and reflective foil to facilitate heat transfer better. The entire bundle should be wrapped with at least 3/4” of foam insulation. Some manufacturers offer 1” insulation as an option.

The whole bundle is secured in place with PVC tape. This outer jacket protects the bundle from moisture and pests. Some manufacturers try to shape the outer jacket for less surface area, so it is easier to pull through walls during installation.  Typically, one line chiller would be used to cool as many as eight different beer lines. In that case, the bundle would be two glycol lines (one outbound and one inbound) and eight beer lines. Some bundles will have up to 12 beer lines with two glycol loops (four lines).

Chill out

The glycol has to be chilled, of course, before it circulates through the lines to the tap and back. Small refrigeration units called line chillers or power packs cool a food-grade solution of propylene glycol and water. The units have compressors that range from 1/3 hp up to 2 hp. The size you want will depend on how many beer lines you have and the distance from kegs to tap. There are two basic types of power packs. The most common design puts the evaporator in a reservoir of glycol. The chilled glycol is then pumped through the lines, circulating up to the tap and back to the bath. One manufacturer uses an agitator motor in the reservoir to keep the glycol circulating around the evaporator coils.

The other type of power pack is a sealed system. Rather than immerse the evaporator in the glycol solution, the glycol lines are sealed and run alongside coolant lines through a stacked plate heat exchanger; in other words, through the evaporator itself. Far less glycol is required in these systems. Some have only a small 1-gallon reserve bath versus typical glycol bath systems, which often have 15-gallon reservoirs.

The concentration of the glycol solution in both types of systems must be checked regularly, and you need to change it occasionally. Glycol solution in chillers using a bath must be checked three or four times a year, subject to local health codes, and has to be replenished or replaced every year or so. Glycol in sealed systems will last far longer. Many units with glycol baths now have a sealed lid to help preserve the concentration and quality of the solution, but you need to check with local health departments for applicable regs.

at the tap

The trunklines run to the bar, where beer lines are routed to each individual tap. Ideally, it would be best if you kept the beer as cold as possible for as long as possible, which means all the way to the faucet. Here's where things can get tricky.

Beer towers make a big difference. Towers come in all shapes and sizes, including columns,  mushroom, “T,” double pedestal and pass-through, custom towers, and they're made from all sorts of materials, from chrome and brass to wood and ceramic.

No matter what the style, look for towers with an internal insulated cold plate or block, and make sure the glycol lines run all the way to the tap. In one standard design, a copper tube lies on top of or is zip-tied to the faucet shank. The glycol runs through the copper loop, chilling the shank. In newer designs, the faucet shank screws directly into the cold block. Manufacturers claim the latter design is less likely to leak and provides better cooling at the point of dispensing.

Frozen beer towers are big in some operations. At least one manufacturer makes line chillers with oversized compressors to give them the ability to recover quickly and keep glycol temperatures around 28° F or 29° F so that it will keep beer close to 32° F over long distances. When the very cold glycol circulates through the cold plate in specially designed beer towers, condensation from the ambient humidity freezes on the tower's metal surface, encasing it in ice. The effect is primarily
for looks, but remember that in dry climates like Arizona, the effect may be less than impressive.

Faucets are food contact surfaces, so they should be constructed of a material that won't corrode or impart a flavor or odor to beer. Older fixtures often had internal parts of brass or plated brass. Most fixtures now are made of stainless, but double-check and insist.

Bar design may well dictate the type of drain pans you use. The bar might overhang the drink rail, for example. Some beer towers are designed to be mounted right into a drain pan instead of the bar top. The advantage is that spills and splashes are more likely to go down the drain and less likely to seep under the tower and rot the bar
top.

design considerations

Plan carefully before you start to spec your system. Just because it's possible to send beer on 1,000' runs doesn't mean you should do it. If you're building from the ground up, consider locating the keg
storage walk-in directly behind the bar like Buffalo Wild Wings does.

If you're retrofitting a draft system to an existing store, try to minimize the distance between the walk-in and the bar. The Cowboys Stadium in Dallas was built without forethought for a draft beer system. But instead of running long, long beer lines from existing walk-ins to concessions, small walk-ins were added closer to dispense points throughout the stadium.

As mentioned earlier, longer runs and heavier beers often require higher pressure or a beer pump. Regardless, you still want a limited flow rate, usually about one gallon per minute, at the tap. To limit
flow at the dispensing head, you'll have to use a length of smaller-diameter tubing connecting the trunk line to the tap faucet.

Like a merge lane that slows traffic, this narrower, restrictive line will vary in length depending on how much you need to slow the flow rate. Whatever the length, keep it in mind when you work out your total line length, and think carefully about where and how trunk lines will come into the bar.

Where you run the individual beer lines in the bar is another consideration. They may be run under a wall if it's new construction or under the counter if it's a retrofit. Either way, think about the implications for future maintenance and make sure there's room for the lines. Know in advance where you plan to locate kegs and tanks on one end and beer towers on the other. Once the beer lines are cut, it won't be easy to change placements.

Options and add-ons

There's a host of gizmos and options available to make your draft beer system work better with fewer headaches.

FOBs, or empty keg detectors, have popped up on the market recently. These valves detect foam, signaling when a keg is empty. They automatically close the beer line, and when the keg is changed, the valve opens, and the beer starts flowing again without having to clear the line of foam. These detector valves can be wall-mounted in the walk-in, or in some cases, incorporated into the coupler that connects the keg to the beer line. The devices cut down on waste, saving you money.

As mentioned earlier, each keg or each type of beer requires its own combination of temperature and pressure to produce a good pour, depending on how far it's located from the tap handle. Thermostatic pressure regulators allow you to control the kegs' walk-in temperature, glycol temperature for the beer lines, and pressure. If one of those parameters is off-target, it can put the whole system out of balance, resulting in a less than ideal pour. Thermostatically controlled pressure regulators automatically compensate for a rise in walk-in temperature.

If you use a gas blend, nitrogen generators can be useful, eliminating the hassle of storing and changing nitrogen tanks—finally, CO2 detectors. Carbon dioxide detectors sound an alarm if CO2 levels rise above acceptable levels.

For an excellent guide on how to set up a draft beer system, download a copy of the Brewers Association's Draught Beer Quality Manual at draughtquality.org