Bodgineering - DIY carbonation

[patrickl]

OGB, any chance you could post a link to the bits you bought to attach to the cylinder? Whenever I embark on this kind of thing, I seem to end up with a pile of incompatible parts. (I'm still baffled by the array of air compressor fittings available...). I'm hoping CO2 welding gas comes in a UK standard format? I do love a bit of fizz!!
Many thanks
Patrick

[Oldgreybeard]

OGB, any chance you could post a link to the bits you bought to attach to the cylinder? Whenever I embark on this kind of thing, I seem to end up with a pile of incompatible parts. (I'm still baffled by the array of air compressor fittings available...). I'm hoping CO2 welding gas comes in a UK standard format? I do love a bit of fizz!!
Many thanks
Patrick

I'll list the bits once I've tried it out to see how it works, that way if bits need to be changed you won't get a duff steer, but these are the trial bits I've bought or ordered. The basic set up for my test run is:

A 390g disposable welding gas bottle like this: https://www.ebay.co.uk/itm/313487595077

A pressure regulator that will fit this bottle, and which has an output pressure gauge, like this: https://www.ebay.co.uk/itm/284898102301

A stainless steel hose tail that can be fitted to a bottle cap, like this: https://www.ebay.co.uk/itm/154780116079

I have some left over lengths of PU air line that I'll use to connect the regulator to the hose tail fitting.

The regulator can later be adapted to fit a standard refillable CO2 bottle (much cheaper than the disposable bottles) using an M10 male to Type 30 female adapter which I'll get once I've seen whether or not the system works OK.

[Oldgreybeard]

I should add that if you just want to re-use empty 1 litre or 2 litre PET fizzy drinks bottles, then because they all have a common thread size you can buy an off-the-shelf carbonation cap, made from stainless, together with a fitting that will take the CO2 tubing. The regulator on the gas bottle attaches to this and is used to start the flow of gas and control the carbonation pressure: https://www.ebay.co.uk/itm/283998358785

[patrickl]

Thanks OGB, you're a star!

[Oldgreybeard]

First experiment completed - works fine. Here's a photo of the test rig:

DIY Carbonation 1.jpg (122.58 KiB) Viewed 1241 times

To use it the bottle is filled with ice cold water (cold water dissolves more CO2) and then the cap is swapped for the modified one with the gas pipe. With the bottle stood upright (doesn't matter what position the CO2 cylinder is) the regulator is cracked open until bubbles start to appear, with the cap not screwed on tight to the bottle. This purges the air in the space at the top of the bottle. As soon as it's purged, the cap can be screwed down and the pressure increased with the regulator valve. Shaking the bottle vigorously helps to dissolve more CO2. For this first test I took the pressure to 40psi and held it there for maybe a minute, with the bottle being shaken for maybe 30 seconds or so.

The regulator is then shut right off, the cap unscrewed from the bottle and an unmodified cap fitted in its place. This worked a treat, pleasantly fizzy water without being too vigorous. Next I need to try upping the pressure to see what effect that has. It's OK to go up to around 50 to 60psi, and this fairly cheap regulator seems to be very easy to control, so setting any pressure is pretty easy. Some close ups of the bits, the regulator:

DIY Carbonation 2.jpg (114.75 KiB) Viewed 1241 times

and the modified bottle cap. At the moment I've just fitted a fibre washer either side of the stainless hose tail, but really I think it needs a Dowty washer, for hygiene reasons as much as anything else. I suspect things may grow in the wet fibre washer after a time.

DIY Carbonation 3.jpg (65.37 KiB) Viewed 1241 times

DIY Carbonation 4.jpg (67.8 KiB) Viewed 1241 times

One change I made was to replace the 8mm pneumatic fitting that the regulator came with for a 6mm one, both because I had some 6mm pneumatic tube and because the hose tail I bought turned out to be 6mm, although advertised as being 8mm (turns out the 8mm was the size of the flats on the hex part, I think).

[Oldgreybeard]

An update. All has not gone smoothly! The cheap regulator I bought (an eBay special) had a cylinder seal that seems to have been made from chewing gum. On the third bottle of fizzy water the regulator pretty much stopped working, passing very little gas. When I looked closely at where it screws to the cylinder I could see a string of the seal material that had been extruded out of the vent hole. The cylinder was still sealing to the regulator OK, but the seal had squished so much that it had closed off the small hole that allows CO2 into the regulator.

I tried popping a 6mm x 2mm O ring in and that worked for a short time, but then that too extruded out of the vent hole. Amazing what about 900psi can do! I've just 3D printed some seals up from TPU, and so far they seem to be holding up. No idea what the proper seals are supposed to be made of, something harder than nitrile rudder or the weird clear plastic the original was made of. I don't have any thick fibre washers of the right size, but might try and get some, as I think a fibre washer might better be able to stand up to the pressure.

The good news is that the rest of the kit works well, in fact it's easier to use than the Sodastream was, quicker and makes less mess. I follow the same method I used to, cooling bottles of water in the fridge before carbonating them. Very quick and easy to get a bottle out, swap caps, squirt in some CO2, give the bottle a shake, then swap caps again and put the now fizzy water back in the fridge. About 45psi seems optimum for my taste. 50psi is a bit too violently fizzy, 40psi is OK but the fizz wears off a bit after a while.

The system works well enough to be worth doing properly, so in slow time I'm going to get a better regulator, one that will fit standard pub CO2 bottles, and get one of those bottles to go with it. I don't need to change the bottles, cap, etc, as that all works a treat. Just bought some vanilla extract and am going to have a go and making cream soda next.

[Fintray]

I'm following this with interest as my wife was thinking of resurrecting to old Sodastream to make lemonade instead of buying so many plastic bottles (got rid of buying in bottled water by getting a distiller) and as I have a full size pub CO2 bottle and regulator I might give it a go.

[spread-tee]

Most regulators at that kind of pressure have a metal to metal seal, propane, Oxygen, and Acetylene cylinders I have all use a conical brass fitting with no washer. I don't think the MIG Argon does either.

Desp

[Oldgreybeard]

Most regulators at that kind of pressure have a metal to metal seal, propane, Oxygen, and Acetylene cylinders I have all use a conical brass fitting with no washer. I don't think the MIG Argon does either.

Desp

Puzzled me, TBH, as I'm used to the sort of conical metal on metal fittings, but it seems that CO2 uses flat faced fittings with seals. No idea why, but even the pub bottles are like this. This is the cylinder connection for a standard large CO2 cylinder (the bottle thread is BS341 No. 8 male) and you can just about see the sealing washer in this photo:



The disposable bottle I'm using as a stop gap/experiment also has a male thread and a flat sealing face, but smaller, M10 x 1.

[Fintray]

Most regulators at that kind of pressure have a metal to metal seal, propane, Oxygen, and Acetylene cylinders I have all use a conical brass fitting with no washer. I don't think the MIG Argon does either.

Desp

Puzzled me, TBH, as I'm used to the sort of conical metal on metal fittings, but it seems that CO2 uses flat faced fittings with seals. No idea why, but even the pub bottles are like this. This is the cylinder connection for a standard large CO2 cylinder (the bottle thread is BS341 No. 8 male) and you can just about see the sealing washer in this photo:



The disposable bottle I'm using as a stop gap/experiment also has a male thread and a flat sealing face, but smaller, M10 x 1.

As the CO2 cylinders (from BOC) have a maximum pressure of 50 Bar, I would imagine that the regulators have a different fitting to prevent anyone trying to use the regulators on any of the other higher pressure (up to 300 Bar) gasses.