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All Fizzed Up -- Carbonating Draft Beer in Pubs Is a Gas
By Richard Cusimano
The proper proportions of CO2 and nitrogen can deliver the taste the brewer carefully
put into the product
The next time you are enjoying a cold beer at your favorite watering hole,
you might want to think about the role gas and technology play in producing
its foamy flavor, texture and appeal.
First, of course, are the natural ingredients used by beer-makers worldwide — barley,
hops, water, and yeast — that undergo a series of complex processes.
It all begins with crushing the grain to release starch and flour, then mixing
the grist with hot water. Mashing comes next, with malt enzymes converting
the starch to fermentable sugar. Then the strained mixture is boiled. Hops
and barley are added for color and flavor, and yeast produces the alcohol and
some of the carbonation (CO2).
Beer producers spend a great deal of time to research and create their “recipe” for
a great beer. This involves determining the proper balance of natural ingredients
along with just the right amount of carbonation to give the beer its palate
appeal. But it’s not only a question of taste; the end result must be
pleasing to the eye as well. Once the beer-maker’s recipe is finalized,
the challenge is to find a way to deliver a consistent product to the consumer.
Your local pub traditionally dispenses beer from a keg using CO2 gas. The
amount of CO2 that winds up in your glass depends on many factors, from how
is poured to the volume of CO2 pressure used. Each beer producer has a preferred
amount of carbonation in the beer. There is also a preference about the height
and density of the foam/head at the top of the beer when the bartender pours
it into a glass. This means the type and amount of carbonation used for each
brand of beer can be different, which can create a problem for the pubs and
the suppliers of the gas.
To complicate matters further, some producers use a combination of CO2 and
nitrogen for dispensing and carbonating beer. The combined gases give the beer
characteristics that are different from CO2 alone. In particular, nitrogen
changes the density of the foam, leading more producers to use this combination
of CO2 and nitrogen gas in their products. Having to provide different CO2
and nitrogen mixes adds another complexity.
Delivering CO2 is a simple matter compared to delivering various mix combinations
of CO2 and nitrogen. There are two basic methods for delivering CO2 and nitrogen
for use in the pub. One method is to use a pre-mixed bottle of CO2/nitrogen
gas and a delivery regulator. Another method is to use a cylinder of CO2, a
cylinder of nitrogen, two delivery regulators, a mixer, and the various plumbing
pieces to connect them all together. In either case, the cylinders and apparatus
must be placed somewhere out of sight and out of the way. A logical location
would be a basement or back room. Sometimes providing adequate space for this
equipment with easy access can be a problem too.
A point-of-use mixing method is usually less expensive and more flexible than
using pre-mixed bottles. These two considerations prompted gas and equipment
suppliers to come up with the original solution of mounting two regulators,
a mixer, and the needed piping to a panel to provide the necessary point-of-use
mixing, and to replace pre-mixed gas cylinders (See Figure 2). While this discrete
component method works well and is an improvement over premixed cylinders,
the call for reducing cost and size and enhancing reliability provided an opportunity
for improving the delivery system even more
Figure 1. A compact anodized aluminum block that holds two
regulators and mixing components used to combine different ratios of CO2 and
nitrogen and dispense beer, is simple to install, has fewer components, takes
up less space, and is easy to access.
In general, as products become more complex, there is a desire to make them
smaller and to integrate functions. Some obvious advantages beyond more functions
in less space are: fewer internal components and external connection points;
ease of integration into other designs; increased reliability; and reduction
of labor costs.
With modern design tools and CNC (computer numerical control) machining, engineers
have greater latitude in designing and building products. The one that is utilized
beer is no exception. Two regulators suitable for use with CO2 and nitrogen
are easily integrated into the left and right side of an anodized aluminum
block. The center is designed to hold the components that make up the mixer.
Locations for inlet and outlet connections are strategically placed. The internal
regulator components such as the seat, filter, and poppet are also integrated
simple, compact design.
Combining two specially designed regulators and the mixing function into a
single, compact package has significant advantages for the producer and for
the end user. The regulator/mixer package is simpler to install than the individual
pieces it replaces. It allows the gas supplier to inventory fewer components.
It takes up less space where it is used and is also much easier to service,
should service be required. It can also solve the problem of providing different
gas mix ratios for the different brands of beer.
The design of this integrated regulator/mixer meets the challenge beer producers
face in delivering their “recipe” for the perfect beer to the consumer.
It adds value not only for beer makers but also to the gas suppliers and barkeeps
as well, insuring a consistency of taste for consumers from pub to pub.
That all said, the next time you are sipping your favorite brew at your neighborhood
pub, pause for a moment and think about the science and engineering that goes
into filling your glass.
Richard Cusimano is Director of Engineering, Concoa, 1501 Harpers road,
Virginia Beach, VA, 23434. He holds A BS from tHe Milwaukee school of engineering,
Memberships in the institute of Electrical and Electronic Engineers and the
Society of Manufacturing engineers, and Patents in the industrial controls
and telecommunications industry. Concoa’s Director of Engineering since
2000, He spearheads new concepts and development of precision pressure and
flow control systems and equipment for new markets And oversees resource/project
planning /design engineering personnel. He can
Be reached At 800-225-0473 or firstname.lastname@example.org.
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