A few months back in the summer I wrote a post called new ways of thinking about carbonation where I started to explore carbonation in terms of grams per liter of dissolved gas instead of pressure and temperature. I set up quite a few projects and so far have been slowly crawling through them.
The first project to be tackled asked this question: Can I easily weigh the gas I add with my car valve carbonator to know how sparkling I am?
I was turned onto the car valve carbonator by the folks at the Milwaukee Maker Space. It is basically a soda bottle with a hole drilled in the cap and a replacement tire valve affixed to the hole. It is an astoundingly cheap and easy way to carbonate. you then a get a tire filler and attache it to your gas supply. set your regulator to 50 PSI and then inject some gas and shake to facilitate dissolving. [it turns out these valves have lead in them and I abandoned using them. I now only use the tap cap and my Champagne Bottle Manifold.]
We used 20 oz. soda bottles that were filled with 500 mL of liquid. The filled bottle was placed on a kitchen scale and zeroed then we weighed after each injection. We were easily able to add 3.5 grams (7 grams per liter!) to our bottle. We then put it in the fridge to rest and come to equilibrium so it didn’t gush when opened too quickly. [I think when I did this I was not accounting for what was in the head space which has a significant weight that can be accounted for by zeroing. Newer things I've written explain the process much more clearly.]
What is awesome about this is that you don’t have to taste as you go, you can learn what 7 g/L tastes like and then keep all your numerous bottles consistent. A jigger for carbonation and its as simple as a kitchen scale!
What I’m really bent on is doing this with champagne bottles or those tiny San Bitter soda bottles. I won’t be impressed until I get perfect carbonation and an elegant delivery. Luckily my champagne bottle manifold works well now that my plastic foundry skills have grown. I also discovered a stainless 19/32-18 to 1/4MPT thread adapter that will allow me to put Cornelius quick release fittings on top of my manifold! The same link also has a 19/32-18 adapter that goes on a 1/4 male flare fitting so you can combine it with a draft tail piece and put a Cornelius quick release on a soda siphon (I know a picture would be worth a thousand words). For a busy bar, the fittings will pay for themselves in a few weeks!
The next thing I wanted to tackle is how much gas actually goes in a soda siphon when you charge it with a 8 gram cartridge. I’m equipped to do this. I’ll have to charge up the siphon, zero the scale, then unscrew the cartridge but leave it on the scale and see how much weight was left trapped in the cylinder. Then I can unscrew the top of the siphon and see the weight of the gas that escapes. Then I’ll know how many g/L of gas made it into the water. I should probably also weight the cartridge to actually see how full it was.
This information will let us know how much dissolved gas we should put in our soda if we want them to compare to classic siphon made versions.
We can also see how much gas is lost to the turbulence of going through the siphon. For that I’ll use the Carbodoseur tool that my new favorite commenter Julia mentioned. They are typically expensive but I was lucky enough to acquire a new one very cheap on ebay.
There is more to be done but I’m off to work.
[I never followed through with exploring the soda siphon because the Champagne bottle manifold was so successful. I eventually even built cradles that allow me to fill 100 mL San Bitter bottles as well as 187 mL & 200 mL bottles. Ideas developed quickly from here and I recommend checking out my Carbonation time line.]