It began as so many engineering projects do – the simple thought, “you know, it wouldn’t really be ALL that hard to do….”
One of my good friends drinks a lot of carbonated water, and on her wish list is a Sodastream carbonation system. I looked at those online, and it offended my open-source sensibilities that you have to buy the filling station, the proprietary CO2 bottles, the proprietary flavoring, and the proprietary bottles to fill. Really, I thought, one should be able to buy a tank of CO2, some appropriate fittings, and do this a whole lot cheaper.
Now I really don’t drink much soda, nor do I care for carbonated water, but as an engineering project this fascinated me. There are even excellent tutorials already available online on this very subject.
I walked myself down the street to the welding supply shop (I love living near a technical university – every resource right at your fingertips!) and I plunked my credit card on the counter and asked to buy a CO2 tank. “What size?” asked the sales person. Um… what are my options? I hadn’t even give it a thought. After some consideration, I went with a 5lb tank that would fit under the sink. “And what regulator would you like?” continued my helpful associate. Well, gees. I have no idea. “Are you making beer or soda?” he asked. Hey now, hey now – why does that matter? I can make what I want, none of your business! 🙂
But after some online research, I have become much more knowledgeable about regulators – and why they sell different ones for beer than for soda (and here I just thought the welding supply guy was trying to feel out how much of a beer drinker I was…). When you build a kegerator (which a startling high number of my mechanical engineering grad student friends have done), your goal is just to have enough pressure to drive the beer out of the keg, and to have an inert gas fill the gap in the keg (instead of air, which will make the beer go bad faster). But with a soda maker, you actually need to drive CO2 into solution, so you need more like 50-60psi instead of 7-10psi for beer. So if you bought a beer regulator with a second stage gauge that only goes to 30psi, you will peg the gauge when you try to go up to 60psi.
Well you learn something every day.
After the tank and the regulator, which were the big ticket financial items, I placed a McMaster-Carr order for fittings, tubing, a 1/4 turn ball valve with a safety lock, and some bike tire valves.
It really didn’t take all that long to assemble once all the pieces in place. The only thing I would note is that I did also buy a bracket to secure the tank to the side of the cabinet – some of the online tutorials skip this step, and while the chance of danger is fairly small, it always makes me feel better to have pressurized tanks strapped down!
After the CO2 filling apparatus was installed, I eagerly tried filling one of the bottles with bike-tire-stem-modified caps I had done earlier that week in lab (drill press. panel punch. laser cut spacer ring. ftw.)
And, success! After some trial and error on how much time was needed to carbonate the water to the appropriate sparkling consistency, we have our own soda water!
So was it cheaper than just buying a Sodastream? Perhaps. Maybe. Not really. But was it a whole lot of fun, and much more satisfying? Oh yes. The damage:
- $22 Wall mounted bracket
- $64 regulator
- $80 5lb CO2 tank (each refill will only cost $20)
- $10 set of 12 tire stems
- $18 tubing and fittings
- Total: $194