Operation KEG Part 2: Kegbot 101

[Image Credits: Mike Wakerly, Kegbot.org]

The Venture Café bar staff recently outfitted one of the taps of the kegerator with a quick-release keg coupler system, documented for posterity in Operation KEG Part 1. This wondrous surgical procedure enables us to serve European beers. Stop by the Café this Thursday to witness the majesty of Eurobeer cascading into Vegware cups from a keg attached to an S-coupler and enjoy a serving or two! With a successful plumbing project under our belts, we decided, naturally, that the kegerator needed a brain. Our vision of the Smart Kegerator involved instrumenting it to collect beer consumption and visitor preference data. Also, if the setup were capable of providing advance warning of empty kegs, the fine fashions sported by the bartenders would remain unsullied by those last explosive burps of beer emanating from the tap.

Enter Kegbot! Mike Wakerly, an engineer at Google and the Kegbot mastermind, first released the open source beer kegerator control system in 2003 and remains the maintainer of the project. The Venture Café Kegerator Enhancement Group (KEG, overloaded acronyms never get old…) would be fools not to use Kegbot as the foundation for our foray into artificial intelligence. Kegbot consists of seven principal components, four pieces of hardware and 3 software applications:

1.Flow Meter: a low-pressure flow sensor installed in the beer line, the SwissFlow SF800 (actually Dutch), measures flow velocities of 0-20 L/minute. Internal electronics emit an infrared signal that is periodically masked by a 3-blade rotor inside the device. The velocity of the rotor and the frequency of the resulting series of pulses output to a cable attached to the sensor are proportional to the volume of beer dispensed during a pour. Since the volume of the keg is known a priori, the amount of beer dispensed can be measured with enough precision not only to anticipate kegs kicking, but also to provide fascinating consumption data. (We expect to observe a strong correlation between pours per hour and real-time visitor ratings once we start collecting them.)

2. Solenoid Valve (Optional): An electromechanical valve controlled by a relay can be inserted in series with the flow sensor in the beer line to either restrict or grant access to the tap. This capability appeals to those operating communal kegerators who share the cost of beer. Users must authenticate in order to open the tap line and those who drink more, pay more. A number of Kegbotters have reported that the presence of this valve introduces a problematic amount of turbulence in the line, resulting in excessively foamy beer. The Venture Café kegerator vociferously objects to solenoid valves on principle and will be spared the indignity of this feature.

3. Kegbot Coaster: A small (0.7”x 1.5”) printed circuit board, the Kegboard Coaster resides inside the kegerator attached on or near the keg coupler. The Coaster includes a temperature sensor, a connector for the flow sensor cable, electrical connections for the optional solenoid valves, and, of course, a blinky green LED. Power, ground, and data are transmitted between the Coaster and the Controller board over a standard CAT-5 cable that terminates in an RJ-45 connector—in other words, a standard wired Ethernet cable.

4.Kegboard Controller: The Kegboard monitors temperature and flow sensors (one per tap) and opens and closes the solenoid valves. It can also handle user authentication via a 125 kHz ID-12 RFID reader and play a tune and blink LEDs on command. In the original incarnation of Kegbot, an Arduino, a single-board 8-bit microcontroller beloved amongst the Maker set, plays the role Kegbot Controller. A Kegbot add-on board, or “shield,” mates with the Arduino. The Controller shield shown in the accompanying photo provides power to and collects the temperature and flow sensor data from two Kegbot Coaster boards. The relay controllers for the solenoid valves are also mounted on the Kegbot shield. The Controller communicates with the device running the primary Kegbot software application, the Kegbot Core, via a simple serial protocol sent over a USB cable. (We have taken considerable liberties with Venture Café’s incarnation of the Kegbot Controller, which will be unveiled in Operation KEG Part 3.)


5. Kegtab Android Tablet Interface: An Android tablet running the Kegtap app acts as the Kegbot user interface and runs the Kegbot Core, the main control process. Kegtab interfaces the Kegbot Server, a web applications, by accessing the Internet using Wi-Fi on the tablet. Kegtab’s main functions include:

• Monitoring and displaying Kegboard data: communicating with Kegbot hardware, translating flow sensor data into beer pour volumes, uploading drink statistics and temperature readings to the Kegbot Server
• Displaying beer tap configuration data stored on the Server
• Correlating authentication data with drink events.
• Generating new user registrations and drink history reports.
• Taking photos of people dispensing beer with the front-facing camera.


6. Kegbot Server: The Kegbot Server is a web application that stores all Kegbot data in a database and displays a variety of charts and statistics. The Server enables bartenders to add and configure taps, map kegs to taps, map beers and breweries to kegs, track beer levels in kegs, and take specific kegs in and out of service. It supports both login/password and RFID-based authentication and authorization and generates individual URLs for each drinking session. Images and sound files can be uploaded and associated with individual users, taps, or events (e.g., an annoying buzzer sounding after the bartender dispenses the 3rd beer to a Venture Café visitor). The Server includes hooks into social networking sites and other external websites, as well as a standard JSON API for custom client interfaces. The Kegbot server is written in Python using a subset of the Django framework. It incorporates the Celery task queue distributed message passing protocol to handle interfaces to external web apps and social networking sites, Highcharts for chart and graph generation, the Nginx and Gunicorn web servers, and supervisord for process control and monitoring.


In short, Kegbot embodies open source goodness. As inspiring and impressive as it is in its current form, mindlessly cloning the work of others shouldn’t make us feel too good about ourselves. How hard could it be to supercharge Kegbot for Venture Café? It is not, in fact, a Sisyphean task, since one of the bartenders (yours truly) happens to make a living designing electronics. Put on your nerd hat, prepare yourself to throw the dog a bone, and stay tuned for Part 3…


Over the river and through the woods, to the brewery we go

The Mystic Brewery inhabits the Mystic Valley in Chelsea, Massachusetts. Although the Mystic Valley has served as the backdrop to many winter New England traditions, including sleigh races and the Jingle Bells song, Venture Café has procured a taste of summer from the Brewery as a juxtaposition to the wintery weather – and beers brewed for darkness – of the past week.

The Mystic Brewery focuses its attention on history – that of its home Valley, and that of brewing beer. The Brewery takes pride in its location in the path of Paul Revere’s ride across the Mystic Valley to warn the Minutemen that the British were coming, and named its house yeast – Wigglesworth – after a 1600’s best-selling Mystic Valley author (and relative of the Founder) who wrote Puritanical doomsday pieces that contained rants about everything but beer. The Mystic Brewery preserves the brewing methods practiced before modern industrial processes became preferred by most its peers. Inspired by Belgian brewers who still adhere to historical traditions, Mystic makes “living beer,” stepping out of the way to allow microbes to do their job in creating flavor, aroma, and complexity.

Mystic Brewery’s dedication to the “living beer” tradition is embodied in its mashing step, which converts the starches in grain to sugar. The brewer pours water into crushed, malted grain and allows it to steep, releasing sugars from the grain. Because highly uniform malts are available today, modern mashing often requires nothing more than the addition of carefully temperature-controlled water to the malt. This infusion mashing can be accomplished all at once or through a stepwise process by adding water of different (generally increasing) temperatures over time. However, Mystic Brewery, like many Belgian farmhouse breweries, prefers more variance in its mash, resulting in a more complex, multidimensional product. Mystic brewers light a fire under a pot containing malt and warm water and stir it for over an hour until the conversion is complete, a technique known as gradient mashing. While gradient mashing requires the brewer to relinquish some control over the process, Mystic believes that it sets its beers apart.


The Renaud Saison currently in our kegerator is an example of a Mystic Belgian style beer, from a line that Mystic designates as 16°. 16° refers to degrees plato, which is an historical measurement of the amount of sugars in an unfermented beer, still popular in Central Europe. The 16° beers tend to be strong at approximately 7.0% ABV and thus pair deliciously with food. The Renaud is a summery beer made with pilsner malt and Saaz hops, resulting in Belgian beer with notes of spice and fruit.

This Thursday, journey through the Boston winter to Venture Café, to take advantage of old traditions and a delicious taste of summer.

Operation KEG: Part 1


Inspired by the iconic MTV show Pimp My Ride, the Venture Café bar staff has embarked on an initiative to transform the kegerator in the CIC 4th floor kitchen into a tricked-out beer dispensing system of epic proportions. The Venture Café Foundation has agreed to support this endeavor in the form of a Kegerator Enhancement Grant or KEG, an acronym concocted specifically for this series of blog posts.

Unlike some of the vehicles featured on Pimp My Ride, the Venture Café kegerator, with its clean stainless steel lines, does not come across as aesthetically offensive. Nevertheless, several glaring deficiencies lurk within:

1.Beer keg couplers are not created equal. There are 6 primary coupler varieties: D, S, A, G, U, and M System. The 4 taps in the Venture Café kegerator are equipped with D (or Domestic) Sankey couplers, the most prevalent configuration in the USA, limiting the beer choices we can offer.

2. We collect minimal data on which beers visitors prefer and how much beer of which variety gets consumed on any given Thursday.

3. Kegs run out or “kick” without advance warning, invariably spraying beer all over the unsuspecting barkeep.

You may or may not be surprised to learn that Venture Café bartenders Shahin Ali, Robin Coxe, and Amy Tindell hold Ph.D.s in chemical engineering, elementary particle physics, and neuroscience, respectively. One would hope that such an overeducated team could figure out how to offer a more diverse and international selection of beers, collect useful metrics from the kegerator, and train it to be considerate and not disgorge beer on people. In this post, the first in a series documenting significant milestones in Operation KEG, we unveil an experimental scheme that, if successful, will address the Deficiency #1 and will enable the Venture Café kegerator to accommodate European beers.

The residents of Planet Earth seem pathologically incapable of agreeing upon common standards for much of anything, resulting in a veritable plethora of DVD formats, AC power specifications, competing systems of measurement units, and, yes, beer keg coupler geometries. Fortunately though, American beer equipment manufacturers sell all six keg coupler systems equipped with beer ports and gas ports that have standard sizes. The gas port on the side of the coupler has a barb with an outer diameter 3/8″ to fit a CO2 hose with an inner diameter of 5/16″. The U.S. Beer Industry standard for the beer port extending from the top of the coupler has a 7/8″-14 thread that connects to a beer tube with an inner diameter of 3/16”.

After perusing a listing of beer brands and their corresponding keg couplers and weighing our options, we decided to purchase S, A, and G System couplers from Micromatic, as well as lengths of gas and beer tubing and stainless steel screw clamps. It occurred to Shahin that adding quick-release connectors to the gas and beer tubes attached to the new couplers would provide us with the capability to switch them in and out of service quickly and efficiently. Shahin identified 3/16” beer line fittings (Colder MCD2203 & MC1703) and 5/16” gas line fittings (Midwest Supplies 5302 & 5303). The complete configuration will require two female receptacles on the tap side (one for the gas line and another for the beer line) and one male plug for each of the two lines attached to each of the four available couplers (S, A, G, and D System) .

For the beta test, we decided to try out the quick-release system on the new S coupler and the existing D coupler on the leftmost tap in the kegerator. Regular Café visitors will recognize that we typically serve lighter beers such as hefeweizens, extra pale ales, and lagers from this tap. Tim Rowe, CEO of CIC and Chairman of The Venture Café Foundation, has long professed a yen for European lagers. His wish may soon be granted! Shahin and Robin performed the installation of the quick-release connectors during lunch hour on Friday 15 February 2013.

The S-coupler “Before” shot:


The first cut of the new CO2 line with the plug connector at the ready:


Installing the receptacle on the tap-side CO2 line:


Tightening the screw clamp on the S-coupler gas line:


The S-coupler “After” shot with plug connectors on beer and gas lines:


The D-coupler retrofitted with plug connectors on beer and gas lines:


The MIT engineer deems the system ready for testing!


Will it work with Notch Session Pils?


Mmm Beer!


Dispensing that first perfect cup of beer allayed our concerns that the presence of the quick-connect fittings on the beer line might cause excessive foaminess. [We have ample spare tubing, hex nuts, and washers on hand if any aspect of this endeavor were to fail miserably and we were to elect to revert back to the original configuration with a non-detachable coupler.] We will put the retrofitted D-coupler through the paces at the Café this Thursday. If this first field test succeeds, we will go ahead and install quick-connect fittings on the new A and G couplers. Expect to see a European lager in an S-compatible keg in the coming weeks!

Coming Up Next in Part 2…

Robin outlines a cunning plan to give the Venture Café kegerator a brain by adopting and enhancing the Kegbot Project, an open source beer kegerator control system.

Brewed from the darkness

This Thursday we are looking forward to enjoying some Fade To Black at Venture Café. No, Metallica is not our Special Guest, but I would like to think if James Hetfield and Lars Ulrich were to drink some of this delicious beer from Left Hand, they would have found life slightly less dark.

Dick Doore and Eric Wallace started the Left Hand Brewing Company in the early 1990s, after several years of homebrewing and roaming the Earth in pursuit of tasty beers. They incorporated in Colorado as Indian Peaks Brewing Company, in honor of the nearby wilderness area that is the historical home to several Native American tribes. Doore and Wallace converted a former meat packing plant on the St. Vrain River near downtown Longmont into their dream brewery. They hit a bump in the road when they discovered that “Indian Peaks” was already being used by another brewery for a beer name, but again found a solution rooted in the Colorado land and its history. They decided to change the name of their brewery to honor Chief Niwot, whose tribe had once frequented the Indian Peaks Wilderness Area, and whose southern Arapahoe name can be derived to be mean “left hand.” They opened their Colorado doors on January 22, 1994.

Fade to Black is a seasonal beer at Left Hand, and refers to “that time of year when the light fades away. Brewed for the darkness, Fade to Black speaks in volumes.” The current brew is Volume 4, a Rocky Mountain Black Ale that pours pitch black with an off-white head. It offers aromas of citrus and roasted malts. The taste is balanced by sweet malts (2-row, Munich, Dark Chocolate, Crystal and Carafa), citrusy hops (Centennial), bitter hops (Columbus), and Italian herbal Amara. The result is smooth, complex, and perfect for the dark months of winter.

While Metallica’s song may focus on the fading of life itself, the beer’s name reflects the quickly fading light of the winter sky. However, since the beer is seasonal, its closing line is the same as the song: Now I will just say goodbye. Thus, come to Café this week to sample this beer before its winter song ends.

Spice it up, Sixpoint style

For months, Venture Café searched high and low to find and procure the Spice of Life.  After much networking, negotiating, and yes, begging, it now lies in wait, in our very own tiny kegerator.

The Spice of Life comes to us from Sixpoint Brewery in Brooklyn, New York.  It was founded in 2004 but traces its true origins to the beginning of history, as the “Sixpoint Brewers’ star” (also called Bierstern, Brauerstern,  or Zoigel Star, depending on where said history was taking place) has served as a code of brewing for centuries.  While the origins of the association between the Sixpoint and beer are unclear, many agree that the brewer’s star was intended to symbolize purity, advertising that a particular brew was free of additives, adjuncts, and other beer “contaminants.”  Thus, the six points of the star may represent the six aspects of brewing most critical to beer purity – the water, the hops, the grain, the malt, the yeast, and the brewer – but other accounts associate it with the three “elements” involved in brewing (fire, water and air) and the three ingredients known to early brewers (malt, hops and water).  Today, the Sixpoint Brewery maintains these traditions with a “mash-up of professional brewing experiences, global brewery influences, and unbridled homebrew proliferation.”

The Spice of Life Series at Sixpoint is a controlled experiment focusing on one agreed point of the star: the hop.  Hops are the dried ripe cones from the female flowers of the twining plant of genus Humulus.  These cones contain signature oils and acids that impart particular aromas and tastes on different beers.  More oil typically results in a stronger aroma, whereas more acid increases the bitterness of a beer.  To demonstrate how the hop may influence a beer, Sixpoint has been producing a different single-hop IPA each month: except for the featured hop, the other ingredients and processes remain the same.  The brew is fermented dry to accentuate the hop flavor and aroma.  The Spice of Life in our kegerator features the Nelson Sauvin hop from New Zealand, said to offer notes of tangy fruit and white wine, along with moderate bittering.  In this second year of the Spice of Life series, the Nelson Sauvin hop is part of an effort to showcase lesser-known hop varieties to American craft beer drinkers.

The long-awaited Sixpoint Spice of Life featuring the Nelson Sauvin hop will be on tap this Thursday at the Café.  I advise you to carry on a centuries-old tradition of brewers and imbibers everywhere: spice it up.



Some like it pure; some like to experiment

While some like to experiment and explore beyond the tried and true, the Germans prefer to keep it pure.  Thus, in 1516 in the city of Ingolstadt, Duke Wilhelm IV of Bavaria enacted the Reinheitsgebot, or the German Beer Purity Law, to protect the purity of German beer through government regulation.   The Law dictated the ingredients for beer as well as its prices, and those who brewed impure beer were subject to uncompensated confiscation of their product.

The original Law stated that the only ingredients that could be used in beer were water, barley and hops.  At the time, Germans knew that the barley provided the color and some sugars while the hops balanced the brew with bitterness and served as a natural preservative.  Blind to the world of microorganisms, they did not yet know about yeast and its role to the fermentation process.  Before Louis Pasteur’s work with microorganisms in the 1800s, brewers typically transferred sediment from a previous fermentation to the next without understanding that the process provided the microorganisms necessary to perform fermentation.  In addition to the original three natural ingredients, the 1993 revision of the Purity Law specifies that yeast may be incorporated into bottom-fermented beer (lagers), and that different kinds of sugar and malt may be used for top-fermented beer (ales).

Throughout history, there have been various reasons for enacting and maintaining this Law:

  • Brewers had a tendency to use cheap grain substitutes in beer, which resulted in an inconsistent and lower quality product.  The Law ushered in a new era of pride and enthusiasm for German beer.
  • Bakers complained about competition with brewers for basic ingredients like wheat and rye, and consumers wanted to ensure that they they could buy affordable bread.  The wheat beers brewed today (hefeweizen) are not compliant with the original Reinheitsgebot, but are allowed under the 1993 revision.
  • In 1871, Bavaria asserted the Reinheitsgebot as a precondition to German unification, to prevent competition from other regional brewers who used a broader selection of ingredients.  This protectionism led to the extinction of many German brewing traditions, including the North German spiced beers and cherry beers.  The broad reach of German beer protectionism ended in 1987, courtesy of a ruling by the European Court of Justice stating that beer imported into Germany does not have to abide by the Purity Law.

Modern German regulations allow for a broader range of ingredients (at least in ales), but those with a penchant for experimentation have searched for ways to escape their remaining purity shackles.  One team of scientists at the Technical University of Munich has focused on yeast as a “loophole” to even the Reinheinsgebot of 1516 (although I am sure that genetically modified ingredients also would have been verboten, had regulators known about them).  Their team created a process wherein they insert different genes into various strains of yeast to create substances like caffeine (stimulant) and limonene (lime flavor) during fermentation.  So far, their experiments have shown that their genetically modified yeast can grow in the relevant environment of hops, malts and water in sufficient amounts necessary for their experiments.  Further, they discovered that they may need to take steps to preserve the genome integrity of the yeast strains in their “SynBio Beer”: first brewing attempts revealed no difference in limonene content between the beer with genetically modified yeast and the control beer, perhaps due to loss of the plasmid that encodes limonene synthase.  Regardless of their experimental results, the scientists’ main goal is to “involve, interest and inspire people to reconsider preconceived ideas and encourage them to openly engage in a broad discussion weighing pros and cons of genetic engineering in foodstuff.”

In summary, some like it pure, some like to mix it up, and some like to circumvent the issue by applying scientific principles.  Like Venture Café, the world of beer caters to a diverse range of tastes and perspectives.