Oh kegs, how you vex me.
This will be an ongoing subject because, for some reason, I keep screwing up my kegging. This may be because it should be really simple. Take your fermented beer and put it in a keg. Put the CO2 to it at the PSI which will result in a perfect level of carbonation. Drink until keg is empty.
This is what I normally do. Put fermented beer in keg. Yell and bitch because keg fails to seal. Put keg in fridge and then yell and bitch while I try to figure out why my connector is leaking gas. Once I hook up my gas line I realize I overfilled my keg and the drop of pressure pulls beer up the gas tube into my gas line. Take all my gas lines apart and clean them so I don't get crap growing in it. Drink beer for a couple of weeks. Pull keg out of the fridge because I need the fridge as a fermentation chamber. Let keg warm up to room temp. CO2 won't stay dissolved in warm beer so now every pour is a foamy mess. Try to save beer by bottling warm beer off of overpreasurized keg. Spray ceiling with beer. Put keg back in fridge and try for a couple of weeks to get the carbonation back where it belongs. When I lose patience I just bottle the rest of the beer off of the keg and start the whole process again.
Why kegging is awesome
It is very cool to have your own beer on tap in your house. You can pull a pint, or half a pint if you feel like it (or a liter!) You feel like a professional.
Your carbonation is perfect. No more wondering what will happen when you put in the priming sugar. It turns out just how you want it.
You can really dial in dry hops, cacao nibs, or oak chips. Do your after fermentation additions and taste the beer every couple of days. When it is exactly how you want it then transfer kegs or bottle.
It is faster to get a beer carbonated. If you crank the pressure up your beer can be carbonated overnight.
Your beer will age better. You don't have to worry about light skunking and if you purge the keg with CO2 before you put the beer in you won't have any trouble with oxygenation.
It is way easier to clean one keg verses 50 bottles. Where bottling used to take a couple of hours putting beer in a keg only takes 15 minutes.
You can blend beers, make awesome cider and even pasteurize then carbonate a beer. By controlling how the CO2 is applied you finally gain total control over your beer.
Why kegs bite
Kegs require a special setup to keep cold, either a dedicated fridge or cool room. A bottle of beer you can store in the cellar and then put a couple of bottles in the kitchen fridge without annoying the wife. I only have room at my house for one extra fridge, so it has to serve as a kegerator and a fermentation chamber.
A keg is not very portable. If you show up to a dinner with a couple bottles of homebrew you are a hero, if you show up with a keg you have a problem. Or you will be a hero to your friends who have a problem.
With bottles you always have a pretty good idea how many beers you have left. With a keg there is a tendency to just drink and then suddenly it is gone.
A keg setup is kind of expensive. You are looking at about $30 a keg, then $75 for a regulator, $75 for a tank, $8 a piece for connectors, and whatever you want to spend on fridges, shanks and faucets. A well put together keg system can cost as much as an all grain system.
Screw ups ensue
About a year ago I picked up about 8 pin-lock kegs cheap. This is way more than I have room for but one day I dream of being able to have 10 beers on tap at my house. The first thing I did was take them all apart and clean them, mixing all of the parts together in a bucket of cleaner. As I tried to put them all back together I realized they are not all the same. It took me a couple of hours to figure out which pieces went to which keg, and I don't think I got them all right. There are still a couple of kegs where the nuts don't fit quite right on the post.
Keg lube is great stuff. Smear a little bit on all the rubber seals and your keg will seal much better than using dry seals.
However, under NO circumstance should you Google "How to use keg lube?" with your safe search off. You will see a couple of guys who take the concept of "beer drinking buddy" to the next level. Not for the faint of heart.
Keeping beer out of the gas lines
The best way to seal a keg is to put your PSI at about 30, which will pop the lid into place. However, when you carbonate it you will only want the PSI to be between 8 to 11. This drop in pressure will pull beer into your gas lines, if the bottom of the gas tube is below the surface of the beer.
Probably the simplest way to keep from getting back pull is to not fill the keg so full but this seems morally wrong to me. I want those last couple of beers, damn it!
What I have done is take my gas tubes and cut them down to about a half an inch. I am not totally sure this is the right thing to do, but so far I haven't had any problems. Also, make sure and hook up the gas while the keg is sitting on a flat surface. Don't tip it so the beer level would be below the gas tube. (Learned this one the hard way last weekend!)
Fundamentally, kegs rock, with the caveat that they would be a good deal less of a pain in the ass if I had room for a dedicated keg fridge. If I ever figure out how to use the damn things.