Closed-system pressurized fermentation
 Equipment Needed
1. Kegs for fermenting: They are the only "readily-available" fermentor out there that can hold the pressures needed to accomplish this technique.
2. Two keg tap connectors: One for use during your ferment, the other used in conjunction with the first (later on in the process) when transferring the finished beer.
3. A Spunding Valve: A simple device that has a gauge for reading pressure, an adjustable back-pressure relief valve for releasing excess pressure, and a port to connect to your tap connector. Although this is the chief piece of equipment talked about in this article, this technique can still be accomplished manually. I would not recommend this without at least the use of a pressure gauge, and even then I would not recommend doing this manually because of the constant work involved. The valve is just too simple to make and use, and comes in handy during counter-pressure keg filling (even if you never again use this fermentation technique).
It is just that simple, and most of you using kegs have most of this equipment already. Now keep reading for more detailed information about this procedure, and see just how easy it is for yourself.
 Introduction to the Procedure.
Researching one night on the internet, I came across Ray Daniels's response to another interested party's query about fermenting under pressure in a Home Brewing Digest post. I read a couple of more prompting hints and whispers on other sites as well about closed systems and had the equipment to try it, so I did. The equipment is cheap and most of it is already in a kegger's garage. I have had nothing but good comments from my roommates and others about my pressure fermented beers (most around me hate anything except the big boys like Bud, Miller, and Coors) than I ever have before, and I end up with carbonated beer right out of my primary fermentor. So... I decided to reach out and tell as many people as will listen about the technique I use and have had such ease and success in brewing with.
First, a little bit about the equipment I use so you can follow. I made my own "normal", gravity fed, three-tier brewing system. All of my brewing equipment vessels are converted Sanke style 1/2 bbl kegs known as a Keggle in the home brewing world (thread references and pictures: ), with the exception of my lautering grant (that is a converted Corny keg with pump attached). Fermentation is done in a completely sealed Sanke keg, with 3/4" cut off the bottom of the dip-tube for sediment transfer prevention. This is how I started in the beginning, but I now use a filter and wish I had left the dip-tube uncut. Even without the filter, I really wish I hadn't cut it. Slow transfer later in the process can accomplish nearly yeast free transfers to your serving or secondary vessels/kegs, but you can decide for yourself when you try this out. I ferment the Sanke inside my Lagerator with a Sanke tap connector that has been "modified" (the gas one-way valve has been removed and a spunding valve incorporated to release excess CO2 pressure) (thread references:  ). A spunding valve is simply an adjustable back-pressure relief valve and pressure gauge that has been attached to a tap connector to release excess pressure from the fermentor. They are around $30 to make and the rest of the equipment needed should already be in your brewery, if you are kegging that is. If not, look into what it would cost to get a kegging setup appropriate for your brewing needs. It is also recommended to have a dedicated tap connector (~$30) for the spunding valve. Believe me, this comes in handy later down the road when you start transferring keg to keg prior to serving. Two are all that is required though, one for each keg during a transfer. Think of Closed-System Pressurized Fermentation in a keg like a really large, metal, Mr. Beer kit. Now that you see what I use, let me show you how I use it.
It all starts with chilled wort, but after recent threads about the No Chill Method I am even rethinking more about things to try. For now though, I will explain my procedure. Note: There are many ways to skin a cat and this is only one. I will explain after what I do some other ideas that also work... this is just what "I" do, so please keep that in mind. Ideas spring from the weirdest places and you may get some of your very own just by reading what I do. OK... lets get on with it shall we?
First, I chill and aerate my wort by recirculating it through my Therminator, which is just a brand of plate counter-flow wort chiller from the Blichmann Engineering Company, and then back into my kettle to help drop the temperature as fast as possible. I use a Venturi Device for aeration during this recirculation. Once it is down to pitching temperatures (or below, depending on my wanted process for fermentation), I pitch the yeast into my kettle or lautering grant and start my knock-out (fancy term for transfer) to my Sanke fermentor. The lautering grant is part of my pump setup, so it makes no difference where the yeast is pitched prior to the fermentor. Presently, I transfer with my same hose setup for the kettle wort chilling directly into an open Sanke fermentor. It just makes it easier for me to not have to hook up any other equipment.
[One can also transfer directly into a sealed up fermentor, like I used to do and may do again, by removing the ball-lock back-flow prevention on the “normally” beer-out side of the Sanke tap connector. If this is the case, you will also want to remove the gas check valve piece in the tap connector to release pressure as the fermentor is filled. The spunding valve was attached (but didn't even need to be necessarily if I had simply released the pressure manually with the built in tap connector's relief valve) to the tap connector gas-side and set to 5 psi. I then used to tap the keg and attach my transfer hose from my pump before transferring the chilled wort into my Sanke fermentor. The pump really pushed a lot of wort into the keg and the pressure built up to about 5 psi quickly. My spunding valve released the pressure way too slowly, so I simply kept pulling the pressure relief on the keg tap. I aerated my chilled wort inside my lauter grant and also pitched my yeast there on its way to the fermentor.]
After filling the closed/sealed keg inside of my lagerator, I reinstall the one-way beer check valve, spunding valve to the gas port, and then attach a clean and sanitized serving/testing spigot with beer-line like this.
Now, the only difference in process is I have to seal up my Sanke before doing so.
Finally, time to tap that keg with your spunding valve and wait for David Bowie and Freddie Mercury to start playing in your head every time you go check on your beer. (Achtung!!! Please believe me!!!!! Leave the fermenting keg tapped and on controlled back-pressure relief until it is done. It needs to stay as controlled as possible while the pressure is being released or you will have a huge mess!!!) There is no "Right Way" to do the following, so I will simply share my views on the subject. Many others have been contributing different approaches and pressure levels to this technique on the Closed-System Pressurized Fermentation thread on the forum, but my take is "simpler is better." I say start simplistically and work your way into your own technique for pressure and temperature changes. For example, the method I will describe just produced the best beer I have ever brewed... EVER!!!
Example Beer: 15 gallons of Texas Brown Ale (more hop character than a typical American Brown. This was a 12 gallon recipe brewed using High Gravity Brewing techniques, so that when I added 3 more gallons post chill it would get me to where I wanted to be volume and recipe-wise. I figured if there was a beer that would hide a lot of imperfections, this would be a good one to try out for my first room temperature fermentation. It started at 65*F after transfer into the fermentor and before I rolled it into the house. I tapped it with the above mentioned setup, and the one shown in the picture. It rose to 70*F naturally, which is where my home thermostat was set and temperature was not checked after that. Very simple use of not having to worry about temperature control, but I assume it raised 4 or 5 degrees above this during primary fermentation. I had my spunding valve set to 5 psi, but fermentation took it to 16 psi by the following morning after pitching so I went ahead and set it to 10 psi for primary fermentation. After work, I came home to find the pressure at 15 psi. You can see just how fast the pressure builds and can become uncontrollable. I chose to set my spunding valve to 30 psi for the remainder of the fermentation to get my required carbonation volume per the temperature the beer was at. It is good to note that I had yeast coming out of my valve the whole time, but by leaving it under control it was kept to a minimum volume of about a cup. Still, this was messy and due to the larger volume I decided to put in the fermentor initially, but still much less than one might have with a normally open fermentation and blow off tubing using that much volume to container size.
After letting the beer ride at 30 psi for a couple of more days, I untapped the connector and rolled the keg twice to three times a day to keep the yeast roused. I did this for almost a week before rolling the beer back to the cooler garage. Once in the garage, I let the beer drop to the cooler temperatures and mature for 2 weeks (actually longer due to my Kegerator still being full). Here's the part I deviated from what I normally do.
Normally, I take into account pressure change with temperature drop. I use crash cooling to clear my beer and then set my pressure on my spunding valve for wanted volumes of carbonation after it is down to a good cold temperature like 35*F. It is just easier to not worry when the beer is at 35*F and I you can set your pressure relief to calculated carbonation volumes pressure per temperature. When the crash cooling week at 35*F is done, I transfer into a cleaned/sanitized/CO2 purged serving keg. I use the same tap setup on my serving keg as I did when filling the fermentor initially, and a regular Sanke tap setup on my fermentor to do the transfer. Then, I roll the serving keg to right beside my Kegerator door for another week at room temperature (65*F-75*F depending but constant). After that, I pop it in the Kegerator and start drinking when it is cool.
This brown ale however, was in a cold garage instead of my crashing freezer and was untapped. I had done all carbonation control "hot." Then when the beer was ready to drink, I put the whole thing yeast and all in my Kegerator for serving. I did this out of convenience, and recommend a transfer to another vessel as cold as you can possibly get it... and under counter-pressure. But, I am telling you so you can see how easy it worked out for me. I still say not to leave it on the yeast as I did! Since I am using a filter prior the tap on my Kegerator, it doesn't affect the clarity or taste in any way. Next time I will be filtering my counter-pressure transfer, but this beer... done the way I mentioned... is fantastic! So, seeing how easy this brown was to do, and seeing how uncomplicated I made my process, you might wonder why you read about different pressures at different times and etc on the forum. Well, that is where they have decided to do theirs. The great thing is, it all seems to work well. This is why I suggest getting your feet wet with simple, and then work your way up into researching why you might want to do all the different things people do with this technique. The thread is very long due to people contributing their versions of this technique, and not a single one of us is wrong in doing their own thing. Try it and see! Then, contribute your technique and outcome on the thread for everyone to see.
Now, I don’t know if all the retarded fusel alcohols and esters are true or not (per the articles that inspired me to experiment with this), as well as the increase in diacetyl followed by the fast decrease upon finishing fermentation. All I know is the beers are fantastic young and only get better with more maturation time. I do this technique for ease, not for some miracle beer.
 Summary of the Process
1. Brew as you normally would be it extract, partial mash, all-grain, or any other method like Brew in a Bag (BIAB).
2. Chill and aerate your beer, or use a technique like No Chill Method and pitch your yeast once at pitching temperature.
3. Now, transfer to your Sanke or Corny keg and seal it up. If using a Corny keg, you will need to give it a shot of CO2 from your bottle to seat the seal of your keg so you can build up pressure. Pressurizing it to 1 psi is good enough for this. Otherwise, just let the pressure rise normally.
4. Once pitched and sealed, set the spunding valve to your wanted pressure release setting and let it ferment. Here you have several options only limited to how easy or hard you wish to make it. All of the techniques you can read about work, and people have their own opinions why they do what they do. I like to go with higher pressures from the start to keep my krausen down, but a other people have steps they like to do... such as lamarguy. Here, my suggestion is to start simple and then expand your own technique from there.
Another approach, that I do not consider Closed-System Pressurized Fermentation only as far as this article is concerned, is to ferment open (meaning normally, like with a blow-off tube or an air-lock) and then "spund" at the last part of primary fermentation. This is done with the last 20% or so points of potential gravity so that you can still achieve natural carbonation. This in and of itself is a technique used by many German breweries, and I only separate it from Closed-System Pressurized Fermentation because I am trying to describe a specific technique with a wiki article. I personally do consider it pressurized fermentation, but it really is no different than keg or bottle conditioning. It works, I just like pressure the whole way through.
5. If you have set up your system to have a testing spigot, or you have another way to check your gravity, you will need to see where you are at in the fermentation to know what to do next. If you are close to final gravity, you need to set your spunding valve to wanted carbonation volume pressure based on the temperature the beer is at. If you have your valve set to this, like I now do, throughout your primary fermentation then you have no worries. Still, check your gravity over a couple of days no matter what your technique to see if your beer is finished.
6. Once you are at final gravity, the beer needs to mature and clean up. I give mine a week minimum at a 5*F increase in temperature for a Diacetyl Rest, but you can use your own schedule. I un-tap my keg and roll or shake to rouse during the maturing period. You may choose to let it sit if you don't have the capability to rouse (or just don't want to), but time is key to yeast clean-up and it will be fine if the yeast are allowed to do their job.
7. Time to clear the beer. Crash cooling, or a significant amount of time, is needed to clear the beer and have a clean end-product. If crash cooling, get the beer as close to freezing as you can before transferring. When the time is right, start your transfer to another vessel to rack off your yeast.
8. Since you have carbonated beer at this point, you will have to use counter-pressure transfer to get from your primary fermentor to your serving keg. This is accomplished by purging your target keg (the serving keg) with CO2, and then pressurizing it to the same pressure as your fermentor keg. Your target keg will need to have a modified tap connector to allow beer in the normally beer-out port, as well as gas out of the normally gas-in port. Attach your spunding valve (set to zero pressure release) to the target keg's gas port and the beer port to the fermentor keg's tap connector. The fermentor keg connector should be a normal tap connector just like if you were serving beer, with the beer port to the other connector and the gas port to your CO2 bottle. Once the two connectors are attached, you can tap them both to the kegs. Since they are at the same pressure, nothing will happen. Start the transfer slowly by raising the pressure released on the spunding valve. You should start to see beer move from the fermentor keg to the serving keg. When you hear the pressure stop being released from the target keg, it is time to up the pressure on your CO2 bottle. Do this until you have transferred all the beer from the fermentor to the serving keg. I always see the beer clear the line and hear bubbles in the keg, at which time I un-tap the serving/target keg and then the fermentor keg to stop the process.
A side note about this process: This is where a filter can be added to get brilliantly clear beer. This is not necessary if you have given the appropriate amount of time for normal clearing, and/or if you were careful and went slow on your transfer from fermentor to serving keg.
9. Now you can store, age/mature, and then serve your beer as you would any other keg of beer.
 Yeast Washing/Collection
I really love how my beer never sees an unpressurized CO2 environment from the time it is pitched with yeast, until the time it hits my glass. Yeast collection from washing is easy with this system. Simply release all the pressure (slowly over a couple of days) and fill the fermentor with pre-boiled and cooled water. Take the fermentor and shake it to mix the trub that is on the bottom into suspension. Let the fermentor settle for about 20 minutes and tap with a "regular setup" Sanke tap during your wait. Then transfer like you are serving into a cleaned and sanitized container and start washing your yeast with the great instructions in the link previously provided.
 Cleaning the Sanke Fermentor
When it is time to clean this gunked-up bad boy, 160*F hot water and a scoop of OxiClean or PBW does the trick for me. I sometimes let it sit for days if I am worried about it being very gunky. Then, I open up the keg and rinse very well with cold water inspecting the keg as I go. I then reseal the keg, and fill with no-rinse sanitizer (Star-San or homemade no-rinse sanitizer). When it is time to dump the sanitizer, I tap with a "modified" Sanke tap (all check valves removed where all ports are open) that lets everything drain out of the tap's "normally" gas-in port when the keg is turned upside-down.
After the first time cleaning the fermentor, I started leaving the keg to clean longer (1-2 days as opposed to the couple of hours I did the first couple of times before). Now-days, I purge the fermentor with CO2 immediately after cleaning, rinsing, sanitizing, and then emptying the sanitizer so nothing wants to grow inside while I wait for my next brew day. This works great and leaves me with ready to go kegs for future fermentation or for filling with delicious barley pop.
I really like this way of fermenting and wanted to share what I have learned/experienced. I hope it keeps working well on all the beverages I produce in the future.
--By WortMonger, member of HOMEBREWTALK.COM 10:41, 13 February 2011 (CST)