Bodgineering - DIY carbonation

[Swwils]

It's not really that simple, but a distributor would give you the correct gas for carbonating water when asked and also be able to provide the spec.

The grade is not just about the purity, but also the handling and containment. And usually the distinction is just the container but not always. For instance you could never achieve food grade gas in a cylinder thats had internal rust, but that would be tolerable and treated with oil in some industrial gas grades.

Gas quality incidents are a specified thing - and brewers know this and you can imagine what sulphur or acetals being in their supply would do. This is why carbon dioxide is often filtered in many pubs to remove flavor-active compounds between kegs and co2 source as a "guard" against any potential problems. It's becoming a more knowledged part of the brewing too, if not already.

For the cost of a few £ and asking it's a simple thing to do regardless of the risk.

[Oldgreybeard]

It's not really that simple, but a distributor would give you the correct gas for carbonating water when asked and also be able to provide the spec.

The grade is not just about the purity, but also the handling and containment. And usually the distinction is just the container but not always. For instance you could never achieve food grade gas in a cylinder thats had internal rust, but that would be tolerable and treated with oil in some industrial gas grades.

Gas quality incidents are a specified thing - and brewers know this and you can imagine what sulphur or acetals being in their supply would do. This is why carbon dioxide is often filtered in many pubs to remove flavor-active compounds between kegs and co2 source as a "guard" against any potential problems. It's becoming a more knowledged part of the brewing too, if not already.

For the cost of a few £ and asking it's a simple thing to do regardless of the risk.

So why is buying certified beverage gas from a reputable and well respected local company such a massive health risk?

I just don't get it, every pub and bar in the land is supplied with cylinders of gas every week from dozens of different suppliers, and yet we never, ever hear of any problems associated with that gas. If I choose to get a bottle of the same gas, from a reputable local supplier (I've spent tens of thousands with Sydenhams over the past decade), then suddenly I'm taking a massive risk with my health.

[Oldgreybeard]

Pretty sure I have the final version now. I swapped the 6mm stainless hose tail fitting in the cap for an 8mm one (one of these: https://www.ebay.co.uk/itm/225010932281) and I swapped the bit of PU airline I was using for a length of proper 8mm HDPE pub gas line (rated for 10 bar, scrounged a short bit from the pub). I added a stainless air stone, with 2 micron holes, one of these: https://www.ebay.co.uk/itm/234673696972 and that makes a big difference to the time it takes for the water to carbonate. The smaller bubbles make carbonation occur within a much shorter time, just 30 seconds to a minute, with less need to keep shaking the bottle to get the CO2 to dissolve. I've also found that 40psi is ample with the air stone, anything over that just seems to waste gas I think.

I needed to swap the tubing connector on the regulator back to the 8mm one it was supplied with. The 8mm HDPE tubing fits and seals well with that connector. I'm using Sodastream bottles and caps, just because I have a stock of them and they are pretty tough, but there's no reason why ordinary 1 litre or 2 litre PET fizzy drink bottles couldn't be used. It's easy enough to drill a hole in a spare cap and add the stainless hose tail, I think. I have now swapped the fibre washers I was using as seals for proper bonded (Dowty) seals. Not sure if they are really needed, but at least bonded seals don't absorb water and possibly allow bugs to grow.

Carbonation fitting.jpg (65.27 KiB) Viewed 772 times

[Oldgreybeard]

I think I have the final version sorted now, took a few wrong turns in the quest to find something easy and reliable, but now have a system that's quick and easy to use and uses recycled PET pop bottles. Final system looks like this:

Final CO2 system.jpg (158.46 KiB) Viewed 713 times

I found that screwing and unscrewing caps was a pain, so I first switched to a "corny keg" type quick release fitting and suitable caps that fit standard PET pop bottles. The corny keg quick release is excellent, seals perfectly and has valves that stop CO2 escaping unless the fitting is locked home. Mistake I made initially was buying some plastic moulded caps (the yellow one in the photos). These are at best a bit hit and miss. They don't have a proper seal for the bottle, so it's pot luck as to whether they leak or not. After a couple of weeks of using them I got fed up with the leaks, so hunted around and found some stainless steel ones on Aliexpress. TBH, I didn't hold out much hope of the Aliexpress caps being any good, but in reality they are brilliant. They are very well made and have a rubber seal and never seem to leak, even on older PET bottles:

PET bottle caps.jpg (108.49 KiB) Viewed 713 times

I also 3D printed a stand for the CO2 bottle, with a bit of felt glued on the bottom so it doesn't scratch surfaces. I don't think I'm going to stick with the welding gas, now I know the system works I'm going to get a larger bottle of beverage quality gas from a local supplier. For now I have a system that's really quick and easy to use, quicker and easier than the old Sodastream. I just fill a bottle with water, squeeze it slightly when fitting the cap to get the air out, then stick it in the fridge to cool down. Once cold it's just a matter of clipping the quick release fitting on and giving the bottle a shake as the CO2 dissolves in the water. When the bottle stops accepting CO2, the quick release can just be popped off, leaving the bottle pressurised.