Primer to Corny (Cornelius/Soda) Kegs & why chose a corny

This guide is split into two parts

history & comparison and general corny maintenance and other info. Part two is in the 2nd post below.

It's fairly typical that someone is going to say I've knobbled the numbers, but it's based on general availability of prices I saw last year (this has been sitting on my desktop for a while).

Ever since getting into home brewing Corny Kegs seem to be on the lips of most serious homebrewers. It’s pretty easy to see why. Corny kegs can be bought 2nd/3rd/4th/etc hand for around £35 – though some work may be required in getting them pressurised.

Corny kegs were originally made by Cornelius Inc in the US, though now several different manufactures make similar kegs. You can expect to pay up to £130 for a new one – an insane price when you look at other cheaper systems on the market.

Originally used by the soda industry to transport syrups etc around they have a number of advantages over plastic kegs, especially the budget ones with 2” caps you can buy in Wilkinsons.

- Made mostly of stainless steel and rubber, almost all the parts are serviceable and can survive a drop.
- Small to medium hands can get inside and give them a scrub (try that on a youngs barrel)
- Blocks all light (no skunking)
- Most people at events seem to have them – so easy to hook up.
- Compatible with most accessories.

Whilst there are two sorts of post (not interchangeable), they are standardised so that your disconnects for a ball lock will fit other ball locks and pinlocks pinlocks etc.

Lets look at the alternatives:

Bottling

A good, bottle conditioned beer is hard to beat. You have several advantages – a dirty vessel will only cause problems with one bottle – you won’t loose the batch (Assuming your primary and / or bottle bucket was clean)
You’ll usually find sediment at the bottom of a bottle which can be off putting to people used to “normal” beer. The big producers manage sediment free beer by force carbonation bottling – no priming.

The disadvantage is having to store 40 bottles for a 5 gallon batch. And clean 40 bottles. And sanitise/sterilise 40 bottles. Then prime 40 bottles (or use a bottling bucket). Then fill 40 bottles. Then cap 40 bottles. Then have your significant other complain because you’ve got a slow build up of bottles in a specialised bin or drying on the worksurface...

The plus side is that you’ll only be paying out for caps and a capper to use bottling – about £25 for a decent two handed capper and a pack of caps. You can also add a bottling wand into this, bottle tree and a bottle cleaner if you want luxury. £100 probably all in.

Plastic Kegging

Plastic kegging is nice and cheap and it’s often how many homebrewers enter the market. Either they’re bought or inherit a keg from someone else. There are three main types of plastic keg – King kegs (large 4” cap easy to get your hand in with a tap mounted 2/3rd of the way up the keg; hambleton bard s30 kegs (extinct but available 2nd hand) 4” wide opening for hand access and a removable bottom mounted tap and nut; finally the youngs style – 2” cap, threaded hole for tap and cheap plastic lid. You can replace the youngs cheap cap with an S20/30 style cap (recommended as the plastic one occasionally builds up so much pressure the tap leaks as my car will testify)
Barrels take up less space and are lighter than 40 bottles. Only one requires a clean, sanitising/sterilising as opposed to all those bottles. You only need to prime the one vessel and you only need to rack to one too.

With CO2 injection it can keep for months as long as you’re careful when dispensing. Dispensing is an art – you have to judge when the flow has dropped sufficiently that it requires a top up. A quick 1 second squirt is all that is needed to make more beer flow forth.

If you don’t have CO2, you have to make sure you stop before oxygen is pulled back through the beer making it stale.
The downside is that the CO2 cartridges are very, very expensive. They’re heavy too, so they cost a lot to ship, so if your local home brew store doesn’t stock them, expect to pay a premium.

Barrels go from £25-£50, £19 for a S30 cartridge if yours has a brass valve on it. A cheap Wilkinsons barrel CO2 lid kit will cost £25 and you’ll need some little dinky co2 cartridges for £5. A S30 valve can be fitted to this for about £15. So for a top range barrel, £70 – if you buy cheap, £60 for a much more inconvenient barrel and much more to modify it to work. You don’t need a CO2 injector, but you better hope you drink your beer within a fortnight without one.

Polypins

Cheapest option. Polypins cost from £5 online with no box to £19 with box in your local home brew store. It’s a plastic bag with a tap on it basically, and as the beer comes out, the vacuum brings the bag in meaning no oxygen is pulled back through the beer making it go stale. The bags are still permeable by oxygen and the beer will eventually go stale. You’ll still need to wash it if you want to reuse it, but no ongoing additional costs.

Casks

The real ale friend. You can’t get metal 2nd hand casks – they’re pretty much always owned by someone and caskwatch is a system for recovering “lost” or stolen kegs.
Buying one is quite expensive and it needs a lot of consumables – probably only a few pence each, but you need to buy in bulk: Keystone, Hard Spile, Soft Spile, Shive. Like all kegs, you’ll only need to clean and sterilise the cask before each use, put in the keystone and rack your beer in. Condition in place and when you’re ready, smack the hard spile into place, praying that it’s not over primed. Once that’s done, you can using a tap and hammer, smack the tap in, remove the hard spile and swap with the soft spile when you’re ready to serve.

You can get smaller plastic “casks” (there’s all sorts of names which are specific to the size, but we won’t go into that here) but they all require the same (but different sized) plastic consumables.

You can add a cask breather which injects a CO2 blanket on top of the beer keeping it for longer. CAMRA will not be impressed though.
Expect to pay about £60-75 for a new cask, £5 for bits, £15 for a tap.

Sanke vs Corny

Sanke

Sanke is very much the most used professional system by small and large brewers alike. It’s standard. A home brewer often has two choices when looking into a good quality system – do I go corny or sankey?

Sankes big advantage is that _everyone_ in the professional trade uses them these days. There are some different types (S types, D types etc)
Expect to pay about £50 for a brand spanking new keg. They’re mass produced – and you can get your brewery name stamped into them. You’ll need a tool for taking off the connectors (£25 unless you make your own) – each fitting is around £25-30. Of course you’ll also need a number of other things such as a regulator, gas and beer lines, line cleaner, tap, CO2 bottle. But the “base” cost is about £100.

Cleaning a really rotten/dried Sanke keg is a complete pig or so I’m told, however most keep them pressurised and moist so they wash out without too much effort. In industry a hot caustic wash is used, but that comes with a fair few risks to the amateur brewer.

Corny

Corneys can be picked up for as little as £35. Their prices do spike from time to time, but that’s about as cheap as they get. The connectors (of which you’ll need two) are £7 each (£15 total) if you get them with line spikes on. So that’s £50. Cheaper than Sanke – but they’ve been abandoned in the face of Sanke. At the moment there is lots of demand from the amateur market to keep Corny parts continually manufactured. So it’s no big problem yet. Come back in a 5-10 years and the tune may have changed.

What’s the rest of the setup you’d need for both Sanke and Corny?

CO2 gas bottle – it’s rare to find bottles without a contract. Mine was £18 for the bottle and £16 a refill for 6.35kg. From what I can see, that’s pretty cheap - £35
Regulator - £30
Regulator to 3/8 gas line - £2.30
Beer/Gas line – 75p a meter (needs two meters probably)
Tap - £25+
Sanke total - £195 all in for a single keg/tap system

Corny keg total - £145 all in for a single keg/tap system.

Conclusions

So looking at comparisons:

Polypin: £5-£19
Plastic Keg: £25-£70
Bottling: £25-£100
Cask: £95
Corny: £145
Sanke £195

I’d imagine that pretty much every homebrewer starts off bottling and kegging in a plastic keg and migrates up or loses interest. After all, the vessel makes very little difference in the quality of the beer and that’s what is key. The rest is convenience.

Not much difference really at the end of the day.

The clincher for me is easier access into the keg if I want to clean something without doing a caustic wash.

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This guide primarily focuses on ball lock kegs. Pin lock have the advantage that you really can't force (as far as I know) a gas on a liquid and visa versa... but most of what's here is applicable to both.

Keg Safety

Most of the old corny kegs can withstand pressure up to 120psi. Make sure you check. It’s rare you’ll even go halfway to this level and generally speaking most things are dispensed around 5-15psi

Each of the kegs come with a valve in the top which you can pull and release pressure. This is vital because taking a cold keg out of a fridge and letting it warm up is going to generate pressure. Similarly if you stick it in your car, it’ll build up pressure. Release it by pulling on the split ring keyfob style thing attached to the keg and you get a lovely hiss.

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The tubes inside the keg are two different lengths. The short length is for the gas. When pressurising you’re essentially pouring a CO2 blanket over the top of the beer. An over filled keg with more pressure in it than your gas regulator is putting out is a recipe for disaster – the beer can shoot up the gas line into the regulator. A check valve is a good investment to ensure your expensive regulator does not get ruined, but not 100% necessary. The long tube goes to the bottom of the keg. If you’re sure your keg has a lower pressure than the gas you’re pumping in, you can run the gas through the beer by using a black connector. This helps force carb the beer – though I recommend doing this cold. If there’s a pressure imbalance in favour of the keg, the aforementioned beer in the regulator is sure to happen.

The posts for the in and the out are not interchangeable. That’s not to say you can’t force the grey gas connect onto the post for the out (yes I’ve done it), but it’s best to mark the top of the kegs clearly. I’ve added a dot of red enamel paint to the rubber so I can clearly see which side is gas.

Unlikely pressure barrels, cornys do not naturally vent. You can buy fermentation corny kits that allow pressure to leak off, set by a mini regulator that fit onto the posts. Otherwise never ferment in a corny unless you want a visit from terrorism officers…

Finding a good keg

2nd hand kegs come in all different states. What you’re looking for is that the handles feel good and solid, no visible rust in or around the posts and the base is firmly fixed. Check for scratches inside, preferably none. Most cornys have stainless steel tubes inside, though I’ve found a few with discoloured HDPE tubes in the gas lines. They look horrible but don’t generally affect the beer.

Fill the bottom of the keg up by 3-4” and Pump it up to 10-20psi, take a bottle with a weak water and washing up liquid solution in it (just a few drips of washing up liquid is needed) and spray the posts and the lid area and look for bubbles. If the posts leak, it’s possible you’ll need to replace the poppets. You can get o-rings that you can swap on poppets, but generic ones are pretty cheap these days. Before complaining too much, push the poppets down with the end of a key or similar to see if after a push they seal. Sealing is the number #1 gripe of the corny user.

If the lid leaks, again it’s likely to be a knackered rubber washer – but it does need to be pressurised to seal. Release the pressure, try to reseat it a couple of times. If you have got a spare seal kit with you (a must really) you can swap over the washer and if that leaks too, you could have a bent lid. Lids are available to buy for about £10-15 so bear this in mind if you’re haggling on price.

Cleaning your keg

A pressurised keg will not open... the lid stays firmly in place. This is a good thing for silly humans trying to open pressurised kegs.

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A pressurised keg is a happy keg. Keep it moist and pressurised and probably it needs a good rinse out & a good spray with starsan. Being slightly more paranoid, I tend to dissemble the entire thing and soak the bottom in a couple of litres of oxyclean. You’ll need some big spanners to do this (size 23 metric?) though I think being American, they use imperial, so the metric “sort of work”. The metal/plastic tubes come out and go in the bottom with the rest, remove the rubber seal from the lid and put the whole lot including the lid into the cleaning solution.

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If there's not a black ring around the lid, it's probably stuck itself to the top of the keg...

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There it is... or it's fallen into the beer.

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You’ll need to reassemble, then sanitise with starsan or similar (some are happy with oxyclean and a good rinse with fresh tap water, but I worry about unsaturated granules making it into my beer). I tend to lubricate the lid rubber seal with some Vaseline – I’ve had much less hassle getting my cornys to seal once I did this. I tend to do a few shakes with the starsan before I lubricate the lid, then after I’ve lubricated to ensure any Vaseline is sanitised as best as possible.
Due to the lid lip, removing starsan foam can be a pain, but don’t fear the foam.

cheap oxyclean:

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Give it a good swish. This one was a bit filthy having not been pressurised, so the whole thing was dunked for about an hour in oxyclean.

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This is a helpful video on how to clean a corny with PBW, including the 'half-way bucket flip' technique:

https://www.youtube.com/watch?v=tCwa-qHnA20

Removing/Replacing poppets & Posts
A poppet...

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The above shows a post with a poppet removed. You can see the metal top which is the bit that fills the post hole and stops the beer shooting out. The ball lock valve pushes down on this and allows the beer to flow out or the gas to flow in.

If you’re doing a deep clean, you may find modern replacement posts sort of just fall out. Old ones can get stuck and I use a key on the metal seal to push it out (see pic above, you poke the key in the hole where the poppet should be...!). Inspect for any wear and if all looks good, just go on to reuse them after sanitising. If you’re replacing with replacement poppets, you may find it a complete PITA to get them to sit in the posts whilst screwing them down.

Some recommend bending the pins so they sit nicely on the lip inside the keg, however I find they work fine out of the packet. I put the poppet in the post, turn the keg upside down and just screw them on that way. Sometimes when I’m done I find the poppet hasn’t sealed properly, but a jab with a key on the stainless bit usually makes it pop back into place.

There's a 3rd post below this that shows the poppet being dropped into the post and what it looks like when you've got it in roughly about right. Click here to jump to it.

Replacing seals

If you’ve got manky poppet seals, you can peel off the old seal if you’re lucky or cut it off and slip the new one on. For all my old style original poppets, the new seals never fit. The new poppets are relatively cheap and I tend to just swap the poppet over. The seals you get in new replacement kits seem geared for the universal poppets commonly sold.

This is a leaky poppet seal. Once you've kegged and sealed, spray them with a weak washing up liquid solution. If the do the below, they're leaky!



Jab it with something like a corkscrew point or a key to try and get it to settle in. Same poppet with a little wiggle.



Under each dip tube there’s also a seal (see below – I’d recommend doing these same time as the poppets)

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The lid seal is the easiest. I tend to keep a few spare just in case I drop one into a freshly racked keg…

Dip tube modifications, replacements

Replacement tubes can be had, but generally speaking they’re not consumable parts so unless you’re missing them I’d avoid buying spares. Replacements for the gas are around £4-5 and the long beer tube £12-16.

If you’re in a habit of racking beers which haven’t settled (a tip here is to crash cool your beer before kegging) you can get some trub at the bottom of your keg. Not great for those first few pints, plus you’re putting excessive yeast into your beer lines which will probably mean extra cleaning down the line somewhere. You can shorten the long tube with a pipe cutter, but on normal brews you may end up leaving additional beer in the keg – what a waste!

Purging

You’ve filled your keg with a syphon tube or pump and connected it to the CO2. Are you done? Nope, whilst you may get a small CO2 blanket on top of your beer, use the pressure release valve a few times to vent off the O2. CO2 is heavier than air, so by purging the air in a few short blasts you’ll push the O2 out leaving much less risk to the beer.

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Force carbonation

Once you’ve made really sure your lid and posts don’t leak and you’ve purged, take your very cool keg (the colder the better for CO2 absorbtion), ramp up the pressure (maybe 30psi) and roll it around on the floor or shake it up. Do this a few times overnight making sure that you top up the PSI. Reduce the PSI down to normal serving levels and vent the excess a few times. Your beer is now carbonated. I don’t recommend it unless you’re in a real rush.
Normal carbonation

Otherwise, just leave it connected at normal serving pressure and it’ll gradually absorb pressure over the next few days. Much less effort. I suggest kegging on a Sunday evening – much less pressure to have it ready to drink for that weekend.

Customising kegs:

Clean the keg well - I used a solvent to make sure everything was off it.

I used a lasercut template (though you could do the same with paper & craft knife) and taped it with masking tape onto the barrel.

Spray with ordinary car spray paint. Make sure you mask off the posts etc if you're worried about overspray.

Coming when I have a chance:

-Regulators
-JG fittings
-Taps
-Beer line cleaning

Only a max of 10 pics per post, so a follow up to the poppets!

Dropping a poppet in:

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Poppet in place:

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Syphoning the beer in:

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Reserved for expansion

Reserved for even more expansion.

[Joe1002]

Thanks for taking the time to write this up, I'll have a full read shortly. For me, their massive advantage of sankey kegs over corny's (and the reason I replaced all my corny's)is that the sankeys seal with absolutely no pressure. Many (all of mine) did / do not seal without pressure therefore are ineffective for use with beer engines. I felt confident leaving the gas on permanently with my sankeys, I never would have with my corny's.

Both, IMO are easy to clean, a good soak with hot oxy or PBW does the trick.

Great post. Many Thanks, a great contribution to the collective wisdom.

May i suggest a slight mod to the title tho to:
"Why choose a corny. And a primer......"

Without the full stop i read it as a comparison of a corny and a primer against a corny without a primer .. its late, im dim, Im sure no else fell in my 'ditch' but while i keg i was reading avidly looking for info on this Primer a bit of kit to use with my kegs i had no idea about ,, DOH!

To add to the topic for future reference, this is a helpful video on how to clean a corny with PBW, including the 'half-way bucket flip' technique:

https://www.youtube.com/watch?v=tCwa-qHnA20