15 Feb 2011

On kegging and Gassing

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So, you’ve got 50 gallons of beer in your fermenter. It’s bright and clear, cold and unfortunately, flat. It’s also in a big ‘ole conical – not exactly “serving size”. What to do.We get a lot of inquiries about the next step – arguably one of the most important. How do we take the beer we so lovingly and painstakingly crafted and get it into a glass that we can let our customers enjoy? How do we get it into a keg that we can serve or sell to a local publican or private party?

How indeed.Here at Hess Brewing, when we say that we make hand-crafted ales, we mean that we put our hands on every batch. Every keg. There is no assembly line, no keg filling machine, no brite tanks equipped with carbonation stones. Hand crafted is really a euphamism for labor-intensive, but that’s ok!

Once our beer has fermented out completely in our 60 gallon fermenters that are nearly press-fit into the GDM (glass door merchandisers), we have two paths we follow next to get the beer into a keg. Easiest is if the beer is in the single GDM, we’ll drop the yeast by lowering the temp, collect/harvest the yeast for the next batch, and get ready to keg right from the tank.
You recall a few posts ago, we talked about modifying the conicals for use in the brewery; one of the big modifications was installing a side-port racking valve at the one-gallon mark. I have found now over 45 brews later, that I get considerably more yeast than one gallon on all our beers, regardless of OG (our smallest beer has an OG of about 1060). So I must do something before I can practically use that sideport. First up, harvesting yeast.
From buying fresh pitches from White and Wyeast, I now have a nice collection of yeast bottles. After ample application of Star-San to the butterfly valve at the bottom of the conical and soaking the container in Star-San, along with the gasket, 1.5”TC x 1” MNPT fitting, and a 18” piece of clear tubing, I’m ready to roll. The MNPT piece works out well – it just threads in to the tubing. By “just”, I mean that the ID of the tubing is 1″ and I can thread the fitting in and back it out later in the same grooves, over and over. I hook the TC equipped end of the tubing up to the butterfly valve and crack it open. Yeast begins to flow, sometimes slowly, depending on the type. I have a small bucket there, at the ready, to catch the first 5 or 600 mL of yeast that comes out – the first flockers and other stuff that was first to get trapped in the 90* elbow. Once I can see clean looking yeast coming down the pipe (tube), I get my container ready (grabbing from the StarSan bucket where it stays until I’m ready for it) and fill it up. I’ll often fill up two containers this way (about 800 mL each). Those get marked with the date and type, rinsed and put in the cold room.
If I’ve dropped out enough yeast to get below the racking port, it’s time for kegging, or if it’s a beer that would really do better sitting for a few days in the cold room (like Ex Umbris) I’ll rack from the sideport (after sanitizing, natch) to an awaiting conical (via our small March 315 pump) and roll it into the cold room.
For those beers that get a few days conditioning in the cold room, when it’s kegging day we’ll roll them out on to the floor, sanitize the bottom port, hook up the same yeast collection tubing and drop the junk that has settled out. Since we racked to this conical from the sideport of the fermentation tank, this usually amounts to maybe a cup or two of yeast, etc. Once it’s relatively clear, it’s time to keg.
We have a dedicated keg coupler for the job. First modification was removing the beer-in check ball, then stretching a piece of the ¾” tubing over the threaded end. About a foot or so will do. The other end of this tubing is a 1.5” TC. On the gas in port we have attached (again, by stretching) a long piece of silicone tubing, about 6’ – this is our tattle-tail end. If we overfill the keg we know it when we see beer in this tubing.
To the conical full of beer we attach a short length of tubing (all connections in the brewery are 1.5” TC) to the inlet of one of the small March pumps (a 309 or 315), another short length connects from the outlet to the 12” piece that is connected to the coupler.
The grain scale is employed at this point for a very important reason. We fill by weight. The first time we kegged beer here, we filled until beer came shooting out of the tattle-tail. Do not do that. You will not be able to carbonate your kegs, I guarantee. Filling to the neck eliminates any head space on top of the beer and no matter how hard you shake, or how many days you wait at 40# pressure (like a week isn’t enough), you won’t carb up your beer. We fill kegs near the top, but not too the top.
Thank God for the metric system. How much does one gallon weigh? You may say 8 pounds. And you’d be close. How much does 1 litre of water weigh? If you said 1 kilogram, you’d be spot on. We fill by, you guessed it, kilograms.
A sixtel is 5.16 gallons, or 19.53 litres. After coupling up the keg, I place it on the scale, turn it on, or tare it (zero it out), and make sure it is set to Kg. With that short piece of tubing connected to the coupler, the joint between it and the tubing that connects to the outlet of the pump is just long enough that I can hook the TC clamp on the edge of the keg. Now, if I don’t mess with it, that is, if I don’t go trying to hold it or grab it, when I tare it at that point, I am getting a good zero mark.
Note that when you couple up your keg, the CO2 that is in there from the cleaning process will vent out the gas-in tattletale line. This is important, especially for Keg #2 and beyond. You’ll see why.
Now, open the beer valve and flood the pump. Sometimes, I need to have the pump up on a bucket or some sort of stand. I also find that using a power strip with an ON/OFF switch is mighty handy, as opposed to being plugged right into your GFCI entension cord. If you are particularly concerned about oxygenating, you can have flooded your lines with CO2 at this point. I’m not overly concerned. A small volume of air will trickle up through the valve and through your beer. How much? Well, in 2’ of ¾” tubing, that amounts to 10.5 in3, or about 0.17 litres. Not enough to worry about.
OK, so beer is to the pump, the keg is coupled, the scale is tared (or zeroed), now, turn on the pump using the power strip. You may need to hold the tubing upright for a moment until it fills with flowing beer, but just until full. Then, the pressure of the beer will keep the tubing rigid. Rehook the TC coupling on the top of the keg, stand back and watch your scale.
For sixtels, we fill to 19 kg. For ½ bbls, we fill to 57.5 kg. This leaves us just enough head space over the beer in the keg so we can carbonate it. Note that for plastickegs, they weigh about 21 pounds empty, so you need a scale that can go to 155 or better, because you’re going to be putting almost 129 pounds of beer in there! Ours says 150, it actually does about 153 or so.
If we have two or three gallons left, we half fill (or whatever) a sixtel and mark the keg ring with the actual litres after filling. This is important when you get to carbonating.
Note: When you are approaching your weight target, 19 or 57.5 kgs, get your hand on the outlet of the source conical and the other on the ON/OFF switch. Shut the beer off at the conical first, the pump can run for ½ second or so no problem. You definitely want to shut the conical off though, as opposed to, say, just bending the tubing and turning off the pump, because of what happens next.
Keg is full, valve and power both off/closed. Move full keg out of the way, put new keg on the scale, start coupling the keg. Guess what? If you are relying on your super human strength to bend the tubing over to stop the beer flow, as opposed to the always-reliable valve, when you couple up that keg, the first place the CO2 is going to escape is back up the beer IN line, through the pump and back into your conical. If however the valve is shut, the incompressibility of the beer will force the CO2 to take the other path, that of escaping through the tattle-tale. Take my word for it, shut the darn valve.
So, now we have 3 ½ bbls and a sixtel, or some combination thereof. Quick rinse and into the cold room they go. If the beer is from one of our cold-room brited conicals, it’s ready to carbonate. From our manifold in the cold room, we run a coupler out through the door to the brewery floor so we don’t have to carbonate in the 36* cold room. Gas is hooked up as normal, but for the beer out side of the coupler, I have taken a penny and put it inside the cap. Then the washer, then it is screwed down onto the coupler. In other words, instead of the beer line hose barb fitting, I have replaced it with a penny. When screwed down onto the beer out line, we have formed a nice tight seal that allows us to force carb the kegs.
Through much trial and error, we have found that at 40 psi, a 19 kg-filled sixtel takes about 6 minutes of rocking back and forth, usually accomplished over a 2×4 on the ground to properly carbonate. Not surprisingly, a ½ bbl takes 3x the time. Your mileage may vary. It is dependent on the temperature of your beer of course, your PSI and your alcohol content (Higher ABV = longer to carbonate). Once carbed up, we roll/push/slide the keg back into the cold room and drag out the next one. If you’re doing the math right, it takes about a minute per gallon, so 50 gallons = 50 minutes.
We have found that we can serve these kegs within minutes of carbing them up. Literally. I think one time we waited about 10 minutes, vented off the overpressure (it was still on 40# in the head space), coupled it up to our taps and out came carbonated beer. We usually do not have our production and demand that tight, but sometimes we do.
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