Article - How to Make a Cheap Counter-Pressure Bottle Filler

By Arnie Wierenga - Page 1

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Arnie Wierenga.

The joys of using a single bottle
After years of using 375ml stubbies for bottling my carefully crafted beers, it was a wonderful thing to make the transition from student to worker and be able to afford to get into kegging. A standard 23 litre batch demanded cleaning and sanitising about 60 stubbies. What a difference it makes to only clean one stainless steel keg for 18-20 litres of brew.
Kegging makes things really easy, except when it comes to long term storage of a particular batch, or taking a few bottles to a barbecue, or having a large range of different types of beer at hand at any time.
And so I have found the need to come around full circle. Not that I ever want to go back to the work of cleaning and sanitising hundreds of bottles, or even to store that many of them. But a good bottling setup rounds out any brewery, whether you keg or simply bottle.

The challenge of bottling from a keg
Bottle technology is really, really simple. If your beer is fermented fully, simply add a calibrated measure of sugar or malt and cap. Over a few weeks or a month, the yeast in the beer will carbonate the brew nicely.
You can do the same with a keg, treating it as a large bottle if you wish. One of the simple alternatives for keggers is to force carbonate. All the draught brewer has to do is set a pressure dial on the CO2 bottle and leave it at that.
The trick for the kegger is in transferring carbonated beer from keg into bottle. The idea is that you want to keep all the CO2 dissolved in solution. Serving a beer into a glass is different. With a nicely balanced system, you will get a flow of beer from the tap into glass that knocks the right amount of CO2 out of solution to give that perfect head. It then should have enough carbonation left in the beer to give the right mouth-feel. The problem with bottling from a keg is that any CO2 you lose in the process means there is less available to provide that great head or the wonderful sparkle on the palate when it is finally served.
So an ideal filler when going from a carbonated keg to bottle is one that will not knock out gas in the process of filling.

A really really simple bottle filler
This could be subtitled ‘bottle filler Mark I’. My first keg bottler was as simple as a connection to the keg (liquid out), a serving line, a rubber bung that suited my bottles, and a two part brass tube that could be adjusted in length to always touch the bottom of different height bottles.
The process of filling was to release the head pressure on the keg, connect the filler, add gas to the keg head-space so that a slow flow would begin, and slowly increase the gas pressure as the pressure built up in the bottle.
This worked to a degree, but it lacked finesse, and when the critique came back from VicBrew that all the bottled beers were low in carbonation, I knew I had some work to do.

The idea behind a counter-pressure filler
Dissolved CO2 is knocked out of solution in at least three ways. It happens through changes in temperature (remember how a warm bottle of soft drink goes flat quickly), through flow obstructions or changes (like shaking a bottle before you open it), and through changes in pressure (if your soft drink is gassed and you open the bottle and leave it open it will go flat).
An ideal bottle filler ought to take all three into consideration. One of the subtle differences is the beer line. When you want to serve a beer (rather than bottle it), you actually want a resistive line that slows down the flow of the beer, knocks some of the gas out and has sufficient pressure to pour the perfect beer with perfect head and carbonation. When bottling, you want to keep that precious CO2 that would get knocked out by a serving line. So my suggestion is to go for a food-grade nylon line that does not have this resistance built in.
That should take care of the flow obstructions (because we use a counter-pressure to slow the filling process). To account for temperature, try to chill the whole filler and all your bottles before bottling. The pressure issue is dealt with again through use of a counter-pressure.
A counter-pressure filler works on the principle of keeping pressures in keg and bottle close to equal to minimise CO2 knockout through pressure difference. This is where my first filler failed. There needs to be a slight pressure difference in a counter-pressure design to allow beer to flow into the bottle. Equal pressure means to reason for beer to move, but a slight difference gives a nice gentle flow.
Counter-pressure filler designs abound. Just do a google (www.google.com) search on the web and you will find many fancy bits of plumbing design to do the job. Most of these are quite complicated and therefore expensive bits of plumbing genius, often difficult to operate because they use a couple of taps.
You can buy commercial fillers, with the plumbing pre-made for you with a tap or two to do the work. Grain and Grape can sort you out if this is the way you want to go with a filler. I like the challenge of making something and in this case I have enjoyed making a complex thing in a simple way.

Designing a counter-pressure filler
A counter-pressure filler needs a way of getting CO2 into a bottle to pressurise it; it needs to have a beer line connected to a keg to get that lovely nectar into the bottle, and it needs some way of keeping a slight pressure bias on the keg side to allow beer to flow. A basic filler design might have two small taps or ball valves, one each for the beer line and the gas line. This design requires a bit of manual dexterity (two handed operation and a third hand to make sure the bottle stays upright). I happened, by chance as it were, on an easier solution.

Making a filler cheaply and simply
The filler I made uses easy to get parts. It is also quick and easy to make. The only specialised tool I used was my wood lathe but you don’t need one to make this filler. But first, a parts list: