Corny kegs have been used for decades to store soda syrup, milk, and many other liquids for serving, and they offer all the hardware to be excellent fermentors. They are all stainless steel, are made to be pressurized for liquid transfer, and all parts can be easily replaced. They virtually never wear out! They are probably the next best thing to a pressure-capable conical fermentor, and they are a lot cheaper. Any size will work, but keep in mind that you need to have some headroom to allow for the krausen that forms during fermentation, and even then you may still get blowoff. Pictured are my 15 gallon cornies for 10 gallon batches. We also have used 15.5 gallon Sankey kegs, 10 gallon corny kegs, and 5 gallon corny kegs. All work well as long as you size the batch accordingly to give some headroom.
The fermentors pictured are using two blowoff hoses into a
single blowoff jar. No reason to use a standard airlock when
you have a blowoff tube, and the blowoff tubes are much
easier to deal with.
Fermentation temperature control
No matter what fermenter you use, you need to be able to control the fermentation temps. If you are lucky enough to live where your basement is 65F all year, good for you, but for those of us in the rest of the world, we need to have some equipment. Best thing is a fridge or freezer with a temp controller. You can also use water baths, frozen water bottles in water baths, boxes with airflow from a fridge, and anything you can imagine. There is no limit to the creativity of folks on this subject, and I hope to write more as I get time. I use the upright freezer you will see in many pictures, and a Ranco ETC111-000 temp controller.
Glass can be the best thing to use for general
homebrewing as it is not oxygen permeable, and is suitable for
long-term conditioning. It is clear, and must be shielded from
many light sources to prevent the "skunking" of the beer. It
is also very fragile, and dropping one can result in serious
injury. Always buy a "Brew Hauler" if you are going to be
moving full glass carboys!
Probably the cheapest and most
widely used for the hobby.
Sankey Keg Fermenters;
The typical beer keg can also make an excellent fermenter. The thing to keep in mind is that they are very heavy, especially when filled with liquid. This can be an issue if you need to lift them at any time for your process. There are some people that have modified these kegs to make them into fermenters, and there are some companies such as St.Patricks of Texas that make gadgets that can be used to allow the use of these kegs as fermenters. The pics below show various configurations, and it all depends on what you need. I'd suggest keeping it simple if you go this route, and avoiding any welding unless you already know a great welder.