“For a quart of ale is a dish for a king,” an appreciative William Shakespeare wrote in A Winter’s Tale. And yet – while Bard’s father was an official ale taster, and he enjoyed an occasional pint at The Windmill when not inserting drinking references into his plays – neither Shakespeare nor his characters home brewed.
Had Prince Hamlet taken up the hobby when not plotting revenge against his uncle, he would have stared at the carboy of his first completed batch of ale and rhetorically asked: “To keg or not to keg – that is the question.”
Why a beginner should consider corny kegs for beer packaging
Determining how finished beer will be packaged is the second most important decision a novice brewer will make after selecting a brewing system and its components. Many start with bottling, usually as a cost-saving measure after an expensive outlay for equipment. After a batch or two, however, the time-consuming processes of washing and sterilizing bottles, and filling them, has some brewers wishing for a faster, more efficient system.
This article is written with the beginner in mind to help demystify the corny keg by providing some background information, explaining its anatomy and function, and examining some advantages of using them.
The corny keg is a fairly recent invention, known originally as a “beverage transfer tank,” created by the soft drink industry in 1957. Coca-Cola
invented a system for restaurants called a “Post-Mix” in which a tank of syrup mixed with water and CO2 for carbonation as the drink dispensed into a cup.
While the first tanks were manufactured by the Firestone & John Wood Company, and later Spartanburg Steel Products, the vast majority were
produced by Cornelius, Inc., from Osseo, MN, and so all of these tanks came to be known as “corny kegs” regardless of make.
Homebrewers flocked to these immediately, purchasing surplus tanks and modifying them for beer. It’s purely coincidental that corny keg
s hold 5 gallons and the typical homebrew batch is the same volume.
Today, the corny keg is obsolete in the soft drink industry and has been largely replaced by the drink fountain syrup bag-in-box, yet it continues to thrive in home brewing. Many brewers prefer pre-used soft drink kegs as a reliable, cost-efficient alternative to new kegs that are more expensive. Refurbished older tanks are becoming scarce on the market and sell quickly when they appear.
What is the corny keg?
The corny keg is a stainless steel upright cylindrical tank with rubber gaskets constructed to hold pressurized liquid up to a maximum of 130 psi. It is 8.5 or 9 inches in diameter and from 22 to 25 inches tall, minus the draught line and gas line quick disconnects. It comes in a variety of sizes, including 2.5, 3, 5, 10, and 15 gallons. An empty 5-gallon corny keg weighs roughly 10 pounds and a little over 50 pounds when filled.
The corny keg’s anatomy has three main components: the lid, the gas-side post, and the draught-side post. The oval-shaped lid provides access into the keg. It is held in place through tension by a thick wire handle that folds over.
The lid has a shallow lip to hold a gasket ring that seals the gas and liquid in. The lid has a pressure valve, enabling the user to depressurize the contents. Most have a manual value, operated with a wire ring. A few have an automatic type, known as a “Hansen valve.” The Valves screw into the lid and can be swapped out.
The gas-side post screws onto the keg, using an 11/16 or 7/8 star wrench socket. It provides the link to the CO2 gas line through a gray connector. The post also houses a spring-enabled poppet and a 1-inch gas dip. O-rings are located on the post and the dip tube makes contact with either the gas line quick disconnect or the keg itself.
The draught-side post is identical in size to the gas side but uses a hex socket. It also has a poppet and a long liquid tube going to the bottom of the tank and O-rings to prevent leakage at either the base of the keg or with the quick disconnect.
Corny kegs fall into one of two categories, pin lock and ball lock (the more common)
This is a distinction dating back to the soft drink days when Coca-Cola pioneered the former and Pepsi Co, which wouldn’t be caught dead using its rival’s method, adopted the latter.
Pin lock tanks are roughly 2.5 inches shorter and a half inch wider diameter than their counterparts. Pin lock quick disconnects use a connecting mechanism of horizontal pins on the posts to attach. Of note, the gas side has two pins and the draught three, so the lines cannot be confused.
Ball lock posts, on the other hand, have ridges which ball in the connectors grip. While there are conversion kits, pin lock and ball quick disconnects are not interchangeable.
The keg’s function is a simple application of physics. Carbon dioxide pumps into the tank headspace until an equilibrium is reached. As the keg is tapped, the gas presses on the liquid, forcing it up the liquid dip tube and into the draught line. Like using a drinking straw, the liquid pours from the bottom up. When the tap is shut, the CO2 flow stops when the new equilibrium is reached.
In addition to the time savings of cleaning, sterilizing, and filling one tank versus 53 bottles, there are other advantages to using corny kegs, including:
Force Carbing. Kegging provides the flexibility to artificially carbonate, allowing the brewer to control the CO2 volume and completing carbonation in a fraction of the time as natural.
Lagering and Fermentation. Stainless steel conducts cold well, enabling low temperatures to be maintained. An airlock can be installed in place of the pressure release valve. As the beer is already packaged, it is ready to serve at the end of conditioning.
The benefits of corny kegs are worth considering for packaging and serving your homebrew.