Corny Kegs 101.

Cornelius kegs (and their ‘clones’) are a great way to package beer and they enable you to force-carbonate, reducing conditioning time to a matter of hours. Furthermore, beer stays very stable in a Cornie giving it a good shelf life (providing you can keep your hands off of it). However, they aren’t cheap and the route to a Cornie set-up that works for you can be littered with unanticipated problems. For one reason or another I rushed in a bit, and I’m still learning, and I wish I had sat down and done my homework first. In some ways it’s a little like AG brewing – you can read about it all you want but some things only make sense when you’ve started to get your hands dirty. However, after some initial confusion and frustration things have finally clicked into place and Cornies now have a definite future for me. Hopefully this post can help you to work out what you need, so please learn from my mistakes (a checklist at the end summarises the basic, essential, kit).

What you need to make Cornies work for you.

tap take 2
Cornie keg with a cheap and simple tap fitted. Beware – this type of tap can be locked open for flushing out. Remember to shut it off again before attaching to a keg, unless you want beery feet.

A Cornie on its own is as much use as a bottle without a way to open it. They require a way to get gas in and a way to get the beer out; this is done via ‘disconnects’ which click on to the posts marked ‘in’ and ‘out’ on the top of the keg. Grey disconnects are used on the ‘in’ post, black ones on the ‘out’ – the ‘out’ post is attached to a dip tube which runs to the bottom of the keg, delivering the beer. So ‘Grey=Gas, Black=Beer’ (thanks Sarah!). The disconnects have threads on them for you to attach lines for gas and beer (although you can get taps directly attached to an out disconnect).

Beer and gas lines do not necessarily just cram onto these threads, the ingenious and economical John Guest (JG) Speedfit plumbing system is often used to interface between lines and other parts of your system. I say ‘your system’ because your set-up will likely be different from anyone else’s. JG connectors come in various different gauges, but most home brew set-ups will use 3/8” lines for gas and beer.

Getting beer out

This is the easiest bit – use a tap! Have a look online to see what options might work best for you.

Getting gas in

This is more complex. You can get Cornie lids with S30 adapters so you can give the beer a blast of CO2 from a Hambleton Bard cartridge. Most home brewers use larger ‘cellar gas’ CO2 bottles. This enables you a) to carbonate beer and b) to maintain a controlled level of ‘head pressure’ to deliver the beer. Cellar gas can be difficult to get hold of as a private individual, and many places want you to have a bottle to swap for one of theirs, but they won’t give you a bottle to start with (even if you offer a deposit). Cash and Carry outlets which supply small restaurants are a good bet to get you started. At time of writing the deposit was around £25 and the gas around £15.

CO2 regulator attached to gas bottle. A JG regulator connector is screwed onto the left-hand side, and the 3/8 gas line simply pushes in.
regulator tap
The stem on this regulator tap is marked in bars.


You can’t just connect the bottle directly to the keg, any more than you could plug your mobile phone directly into the mains to charge it. You need to get a regulator so that you can control the flow of gas. Take a look on eBay and you might pick up a bargain. You will also need a spanner which fits the nut connecting the regulator to the gas bottle. Use a JG regulator connector on the out side of the regulator and then attach your line between that and the ‘in’ disconnect. Using two- or three- way JG dividers is an economical way to manage multiple Cornies from one bottle, and disconnects are ‘one-way’ so you can leave a disco dangling if you have fewer kegs on the go at any given time.  More complex and refined regulator set-ups are available, if and when your Cornie system develops greater complexity.

So, you can get gas in, and beer out, what else?

Temperature control is important if you want to use Cornies. Many people adapt a fridge or freezer into their own kegerator or keezer to provide a temperature-controlled environment for their kegs, although you might be lucky and have a zone in your home which stays at a stable, cellar-like temperature. As well as changing the way you experience your beer, temperature also has an effect on carbonation levels so this is something to take seriously, and a potential additional expense.

Think about the size of keg too. They come in a variety of sizes, but 19l is fairly standard. This means that 19l is the total capacity right to the brim, so you might end up bottling some of your batch in order to leave a bit of a gap (ullage) at the top of the keg. Apart from anything, you want to be able to get the lid on without it dipping in the beer. Do your homework – cheap might not be good, and manufacturing standards vary in different parts of the world.

Quick guide to using a Cornie

Don’t forget that you are not using a keg for conditioning by priming and refermentation (apart from anything you would get lots of sediment in your beer because the dip tube sits very low). Most people want their beer as clear as possible so they use finings and / or crash-cooling to drop as much yeast and other matter out the beer as possible. Crash-cooling is as simple as dropping the temperature of the beer to about 3 or 4 centigrade for a few days – a bit like mini-lagering.

Then, take your sanitized keg and, lid off, give it a short blast of gas. This is to help expel oxygen from the keg, CO2 being the heavier gas. Siphon your beer into the keg, leaving some room at the top as mentioned. Then set your regulator to 30psi / 2 bar and open the gas tap for a second and shut it off again. Then ‘burp’ your keg by pulling the ring on the pressure release valve in the lid – this will expel any residual oxygen and help keep your beer from going off. Then open the gas tap and let the CO2 in. You should hear the gas hissing in, and then once the pressure reaches 30psi / 2 bar it will go quiet. Turn the gas off, disconnect everything from the keg and give it a really good shake! Then leave it over night. Although you are carbonating at 30psi / 2 bar you want to deliver your beer at about half that pressure, so set your regulator accordingly, hook up the gas and draw your first pint! If it’s over carbonated don’t panic. There are various simple techniques for de-gassing (look on YouTube), and often simply burping the pressure release valve and leaving it for an hour or two will do the trick.

lid assembly
Note how the lid goes inside the keg to ensure a tight fit from the internal pressure. Remember to leave space to accommodate this when filling.
lid on
Once slotted in the lid assembly is turned 90 degrees and clamped into place.


Recap – checklist of things you need:

  • One or more kegs
  • CO2 gas bottle / supplier
  • CO2 regulator
  • JG Regulator Connector 3/8
  • Grey gas-in disconnect for each keg (although you can charge kegs individually too)
  • JG Divider 3/8 if running more than one keg from one CO2 bottle
  • JG 3/8 – 1/4 Female Adapter Flare to fit to grey disconnect(s)
  • 3/8 line – how long?
  • Tap
  • A suitably cool environment to keep it all in

Several online home brew suppliers stock the bits and pieces you need, and some sell starter kits. It is a good idea to phone and speak to someone to make sure that all the kit is there. You can probably find some or all that you need across the following businesses (NB this does constitute endorsement by UKCBN and comments are based on my personal experience):

  • Stonehelm

Very good range of John Guest Speedfit stock, and knowledgeable staff.

  • BrewUK

Do a starter kit with two kegs and everything apart from gas. Phone to check. You could arguably get set up for less with a bit of patience and some time on eBay, but handy to have everything in one box, as it were.

  • The Malt Miller

Good quality new Cornie-style kegs at very reasonable prices, and a range of connectors, discos and other bits and pieces. Knowledgeable and reliable service.

  •  Can Direct

Another good source of kegs.


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