Instructables

Brewing Pressure Gauge in a Bail Top Bottle

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I love brewing my own beverages (alcoholic and non-), but after coming home to one too many yeasty explosions I decided it was time take some safety measures.  In most craft brewing, the carbonation is developed by bottling the brew with some extra sugar, which the yeast turns into carbon dioxide.  The building CO2 pressure causes some of the gas to go into solution with the brew -- Viola, carbonation!  The only problem is the rate of gas production can vary a lot, and so if you like to experiment with recipes like I do, your bottles may blow up.

The cheap solution is to brew in plastic bottles, so you can squeeze the bottle to determine how much pressure has built up.  This works well, but purists will turn their noses at the idea.  The theory goes, that plastic has two disadvantages:
1) Plastic is not as impermeable to gas exchange as glass.
2) Plastic can easily develop scratches, which can harbor bacteria that affect taste.
For me, the decision is aesthetic: I really like the look of brew fermenting in glass.  So I wanted to build a way to monitor pressure in a bail-top bottle without sacrificing looks.  I was really happy with the product -- I think it has a nice steampunk look to it.  That said, this project was a lot of work for a problem that can be solved with a plastic pop bottle.

The basic outline of steps is as follows (refer to pictures for more explanation):
1. Take the cap from a bail-top bottle, remove the harness, and cut a welding rod to fit through the hole, sticking out on either side.  Close up the hole with clay.
2.  Create a plaster mold of this cap construction.
3.  Make wax positives and clean them up.
4.  Invest the waxes and burn them out in a kiln.
5.  Cast bronze with a centrifugal jewelry caster.
6.  Clean up the bronzes.  Drill and tap a hole for the pressure gauge.
7.  Bend a piece of welding rod to interface this new cap with part of the old harness.
8.  Put on a rubber gasket and brew up some goodness!

My batches with this bottle have been great -- It's so nice not to have to worry about the bottle blowing up!  I usually brew to a little over 20 PSI, so the gauge is pretty grossly mis-scaled, but it was the only one I could find (it has a 200 PSI maximum!).

The other reason I wanted to pursue this idea was to investigate the possibility of building a forced carbonation set-up.  A set of caps with ports (think bike valve) would be the first step, I think.

Let me know what you think, and be sure to post links to any similar projects.  Thanks for reading!
dugthegreat3 years ago
If you collect bottles . Make sure you test each one by doing a 3 foot drop test onto a concrete or other hard surface. I have never had a problem.

I choose to use champagne bottles which are much thicker.
Hope that helps someone who reads this. :)

streetrod51 year ago
I like the artistry and thought that went into your pressure gauge/cap - I wonder if you could use a tire pressure gauge that has a manual pressure relief valve, so that you could bleed off a few PSI to maintain safer pressure while not allowing air to contaminate your fermentation.

You might have better luck with larger glass containers (1/2 gallon growlers or 1 gallon jugs) - they would take a grommet and airlock. Problem solved! I've been brewing off and on for 20 years, never experienced a broken carboy or bottle; my friend did, though, when he capped off his glass carboy and left town! He learned his lesson after spending the weekend cleaning sticky wine off every surface in his kitchen: air locks are your cheap (but reliable) friends!
timbit19853 years ago
Excellent! I have just started messing around with lacto-fermented soda's. I am using plastic bottles as I haven't had a chance to find any bail-tops.

Also, you wrote. "Viola, carbonation!" Viola is an instrument, I think that you meant to write "Voila" as in "There it is"
jkoznek3 years ago
I didn't see anyone else ask, so I will. Do you check your sg? If you're yeast has attenuated completely and you add 3/4 cup corn sugar (or whatever other sugar and appropriate ratio) to 5 gallons then you should not have bottles exploding unless you are using weak bottles. I reuse commercial bottles and have no problem.
You could do this and then make a wooden "caddy" for them to hold them with an acrylic front so that if the bottle explodes, the glass doesn't go everywhere :)
ZoDo3 years ago
I'm curious, what is the pressure that forms in the bottle? I imagine it's not so big and I think that it would be more accurate if you insert a gauge that indicates a smaller pressure.
Bindlestiff3 years ago
This is very cool. I love everything about it: the look, the utility, concept etc.

I have never worked with metal casting. Assuming I use the right tools and follow the instructions exactly, how likely is it that mine would turn out? Should I practice on some easier metal projects before trying this?
Mtalus4 years ago
I like it, even if it's only to add one more well documented piece of data to my brew log. I had seen pictures of breweries that bottle condition with a gauge head sticking out here and there. Since they used crown caps I didn't quite make the conection to my homebrewing...opps. Well done.
In 20ish years (200 plus batches) I've only had one bottle rupture, the result of a defect I'm sure, (Defect in the bottle that is) but I still think I'll make one.
One more excuse to riddle some sand and fire up the foundry. Or will I invest it? Cheers.
PacStandard4 years ago
This is something that could be very useful. I've been doing some research on pasteurization of apple cider. To pasteurize the brew you can raise the temperature (to ~160 IIRC) of the cider in a hot water bath for 10 minutes or so. It will effectively kill the yeast, but also raise the pressure of the gases in the bottle an unknown amount, which doesn't seem very safe to me. This might just be the tool I need to figure out whether I'm comfortable pasteurizing large quantities.

GasherMan4 years ago
hmm your bottles should not be blowing up!
reasons bottles explode...
1. Fermentation was not complete when bottled
2. too much priming sugar (people add more to get more alcohol, this is pointless as it only raises alcohol by a minute amount)
3. unsuitable bottles..!

been brewing and experimenting for 20 years and never had one bottle explode!
hope this helps and saves you time and money!
kikiclint4 years ago
how hard would it be to make a weighted pressure popoff valve. Have a small piston which you can add weight at the top, so that once the force of pressure equals the mass/piston area the valve raises and vents off a little until the pressure is right again. Add more mass, get higher pressure. It would regulate and prevent overpressure explosions.
calischs (author)  kikiclint4 years ago
That's a good idea. Pressure cookers have just such a mechanism, with various weights for different canning pressures -- I bet you could use one of those.
dimtick4 years ago
Great Idea!!!

A friend of mine got really hurt when a bottle blew up in his face. Since then he's sworn off using glass bottles but doesn't like the taste he gets with plastic.