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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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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.
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
Statistics: Posted by tim_n — Thu Sep 08, 2016 14:48