Controlling Draft Beer: The Importance of the Flux Capacitor | Craft Beer & Brewing

Controlling Draft Beer: The Importance of the Flux Capacitor

As beer has evolved, so has its method of service. This is the story of one California publican and brewer who put technical knowhow into practice to make sure that every pint served is perfectly cooled and carbonated.

John M. Verive 8 months ago

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Photo by John Verive

“It’s probably an overly nerdy thing to do. It’s a solution to a problem that no one really cares about.”

The problem that Gabe Gordon— founder of Southern California’s lauded Beachwood BBQ and Brewing brand—is describing is the imperfectly poured pint, and his solution is a draft system reimagined with craft-beer service in mind. A departure from the standardized architecture of long-draw draft systems designed around serving ubiquitous American light lagers, Gordon’s setup is built for maximum flexibility and precise control.

Dubbed the “Flux Capacitor,” the system can serve a softly carbonated pint of bitter as perfectly as an effervescent keg-conditioned Belgian tripel, and at more style- appropriate temperatures. No breakout. No foaming. No ice cold imperial stouts or kegs slowly going flat if they stay tapped for weeks. The Flux Capacitor is a manifestation of Gordon’s intense attention to detail in every aspect of his businesses, and the system is gaining popularity with a new generation of publicans.

A fine-dining chef by trade, Gordon first wanted to open a high-end ten-table modernist restaurant in the Southern California town of Seal Beach, but he decided a more casual barbecue-and-beer concept was a better fit for the neighborhood. The ’cue would be a fusion of Southern traditions on California style, and the beer nothing less than the best in the world served with all the care and attention it deserves. “Just because it’s beer,” Gordon says, “the tendency [in restaurants] is to treat it as less than wine.” Typical draft systems were built using the standards that work great for macro lagers, but maybe not so great for craft ales, imports, and more esoteric styles.

“Chefs who go the extra mile with ingredients get attention—from customers and from suppliers,” Gordon says. “Why not apply that same approach to beer?” A typical long-draw draft system wasn’t going to meet Gordon’s needs, and he began researching a more novel solution.

Under Pressure

The mechanics of the Flux Capacitor are simple enough, but wrapping your head around the physics and engineering of a draft-beer system can take some effort. Getting beer from a keg to a glass is all about balance—matching the pressure applied to push beer through the system with the amount of resistance the beer will encounter as it flows through coupler, line, and faucet. The straightforward equation is complicated because carbon dioxide will dissolve into a cold liquid under pressure, and this can lead to an over-carbonated beer. (The reverse is true as well—don’t apply enough pressure to a keg and the carbonation that the brewer intended can escape, leading to an under- carbonated pint.)

There are two main types of draft-beer dispensing setups: direct-draw (such as a kegerator or when taps are mounted in the side of the cold box) and long-draw (when the beer needs to travel more than a few feet from keg to faucet). The latter setups are inherently more complex and can involve pumps, chillers, and much higher pressures. The high pressures mean CO2 alone isn’t enough to drive beer through the system because the gas will dissolve into the cold beer and cause a foamy, over- carbonated mess in the glass. A blend of two gases is needed to properly pour a pint: CO2 and nitrogen. The CO2 preserves the carbonation while the N2 (which doesn’t dissolve readily into beer) provides the push the beer needs to get to the faucet. In the typical long-draw draft system, either a bottle of premixed CO2 and N2 gas is used, or a gas blender is employed that can be tuned to work with the specifics of a particular draft system. Both setups work best with a constant temperature and a known level of carbonation in the kegs. The wide variety of craft styles with their varying levels of carbonation can challenge a draft system.

Balancing Act

Gordon’s solution was to create a matrix of secondary gas regulators that can independently control the applied CO2 pressure on each beer line in the system, and it took dozens of hours working in his garage with his father-in-law to create the prototype Flux Capacitor. A bulk CO2 tank and a nitrogen generator anchor the system, and a few different gas blends feed the matrix of secondary regulators that’s mounted behind the bar at Beachwood BBQ. Typically, these kinds of fine-grained draft-system adjustments are made behind the scenes, near where kegs are stored. “That’s like steering a car from the trunk,” Gordon says. He wanted the servers to have direct access to the controls, so he designed a control panel that fit in with the mid-century mod vibe of the restaurant. All chrome and candy- apple red components, the control panel is eye-catching. “We wanted it to look like a sci-fi B-movie prop,” Gordon says.

The focus of the panel is the pressure gauge, adjustment knob, and a shutoff switch for each draft line, and alongside the controls is a matrix of manifolds with quick-release couplings. Each manifold distributes a specific blend of nitrogen and CO2, and short jumper gas lines feed the secondary regulators from the manifolds. This allows endless flexibility, but it takes a long time to put together. It’s also a tricky tool to master. When tapping a new keg, the system is set based on a spreadsheet of beers and known volumes of CO2 levels, but fine adjustments are usually required for the first day or two of a keg’s life.

Justin Evelyn, former general manager of Beachwood who is now hospitality manager at Bagby Beer Co. in Oceanside, California, says, “Often, adjustments must be made by feel rather than calculations. [It] takes some base knowledge of draft- system balance and experience.” Typically, the servers and bartenders don’t make adjustments on the fly. Flow-control draft faucets are used that allow for small adjustments to beer flow when pouring a glass, and fine tuning is left to the management team. “If there’s a problem with a cheeseburger,” Gordon says, “it isn’t the server’s job to go back in the kitchen to fix it. They just need to tell the right people.”

The Future of Beer Bars

The benefits of the Flux Capacitor are not immediately obvious. Flexibility is hard to quantify, and the positive impacts on the flavor of draft beer are only evident to discerning palates. Regardless, Gordon’s design resonated with beer obsessives, and he was hired to install Flux Capacitors at some ground-breaking beer destinations. Tørst in New York City was the first non-Beachwood location to get a Gordon-built Flux Capacitor, and soon the Flux became the must-have accessory for high-end beer bars. Gordon has traveled as far as New Zealand, where he built a Flux Capacitor for Garage Project’s Wellington taproom.

Mikkeller Bar in San Francisco’s 50+ line Flux Capacitor is the largest system, at least the largest one that Gordon has built. When Mikkeller Bar operator Chuck Stilphen started working on a Los Angeles expansion, Gordon decided he’d had enough of the long hours in the garage cutting gas line and gave Stilphen the okay to build his own. “I’m not sure how long it took me. I’m not sure I want to know,” Stilphen says about the process of building a 50-line Flux inside the tire shop that would transform into Mikkeller Bar DTLA. It took two years to get the bar open, and he was tweaking the system until hours before the doors opened. “The versatility makes it valuable,” he says. “We can serve anything—beer, wine, cocktails, nitro coffee—on any line."

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Apart from the flexibility, the reduction in waste, and the positive flavor impacts, the Flux Capacitor has one more hidden benefit—a remedy to a problem that few ever think about. Justin Evelyn explains: “While draft beer has created convenience and consistent quality in many ways, it has diminished an intimate connection to the finer points of beer quality for many establishments. The Flux Capacitor is a step toward building the relationship back.” Evelyn is passionate about serving beer—as are Gabe Gordon and Chuck Stilphen and Jeppe Jarnit-Bjergsø—they all respect the publican’s responsibility to give their customers the very best pint possible. The improperly carbonated glass of beer may be a problem that most people don’t care about, but that problem keeps the noble publican up at night. The Flux Capacitor is a solution and a step toward taking beer service more seriously.

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