Modifying a Sodastream

[Calvin]

I'm not mad and I don't want a Darwin Award. There, that's set the ground rules now to the question.

We have a Sodastream which is fantastic - provided we can get hold of replacement CO2 cylinders we can have sparkling water in unlimited quantities without the hassle of dragging heavy bottles of water home from the shops and the associated waste packaging. Sadly Sodastream as a company are a disaster to deal with. They seem to feel that they can make most money by messing everyone around by changing the system occassionaly and making the old cylinders obsolete. Of course they claim they haven't made them obsolete it's just that they are now hard to get hold of - and Sodastream are the only supplier - oh, and they now have a new system which you can buy for a mere =A350 - and the only real difference is the cylinder fitting.

So, I'm exploring the possibility of either (a) finding someone who can refill the cylinders with food grade CO2, or (b) getting hold of a more universal CO2 cylinder and somehow coupling it to the existing Sodastream mechanism. Does anyone have any ideas of where to try for an unauthorised refill? I've already tried my local BOC agent who doesn't have a suitable fitting for the cylinders so can't refill them.

Alternatively, and much more uk.d-i-y, any thoughts on the practicalities and dangers of a homemade system. I guess I can find a way to couple a cylinder to the back of my existing machine but I've no idea what pressure these cylinders are at and what pressure the Sodastream relief valve operates at. For those who are not familiar with the system the Sodastream is very simple and just allows gas to flow into the water until the pressure opens a relief valve and it "farts" indicating that the fizzy water is ready.

Any thoughts? Calvin

[zymurgy]

Try down at the local brewing shop. They do pressurised kegs which take a self sealing slim bottle of CO2. Check the fitting on one of these.

You might also want to check the operating pressure of the machine before any ill advised 'coupling' ;)

Cheers,

Paul.

[Andrew Gabriel]

CO2 cylinders are used in pubs to force beverages out of cylinders/kegs. The CO2 gas pressure in a CO2 cylinder if fixed because the cylinder contains liquid CO2 - ISTR it's something like 60 atmospheres pressure which is much to high to safely use directly, so you need a pressure reducing valve. I can't remember what pubs use, but I made up a keg of fizzy lemonade once using CO2 at 4 atmospheres pressure from the CO2 line, so it's probably something a little over that (may be less for larger beer kegs). (4 atmospheres turned out to be a bit high and the lemonade was a bit too fizzy.)

BOC supply these CO2 cylinders to pubs, so you could ask them for one, and they would probably supply a pressure reducing valve too. I don't recall the cylinders being expensive (part exchange anyway -- first one might be more). There are some safety issues to be aware of. The two I can still remember are: dangers of having them in cellars (like pubs often do) -- if there's a leak, you can fill the cellar with CO2, which will cause anyone who goes down into it unsuspecting to collapse and suffocate very quickly. If you do get a leak, it's usually quite obvious as the liquid CO2 cools and you'll see the liquid portion of the cylinder ice up with condensation on the outside. The other is the cylinders must be kept upright when in use, with protection to ensure they can't be knocked over (usually chained to the wall). If a cylinder does fall over, liquid CO2 goes into the pressure reducing valve and instantly destroys it, possibly resulting in full pressure and/or liquid CO2 being ejected. If the cylinder falls over and hits the neck on a wall, the PRV will snap off, and you now have a heavy unguided ballistic missile which is capable of punching holes through walls as it rapidly discharges its contents. There are probably other safety issues I've forgotten about.

We used to have a sodastream ~30 years ago, but I can't remember how the valve works. It might just rely on a propreitry valve in the CO2 cylinder like airosols and air dusting cans use, on which case you'll need to include an alternate valve in the CO2 supply. The fart is just a pressure relief valve so you can't blow up the glass bottle. I don't know what sort of pressure reducing valve it had -- possibly just a tiny jet to limit flow to what the fart mechanism could safely handle.

[RW]

Have a look at this lot....

[dvstarling]

Well its an intersting way to keep everyone buying new equipment but there could be design/safety improvements with the new one and it probably looks sexier. I remember the one-shot micro cartridges and the changeover to the first big bottle system in the 80's and that machine was very boxey.

To make a filling adaptor you could try finding an identical model to yours and butcher it for the correct bottle connector bit? Its probably not worth the time and hassle so just give into their marketing/upgrade path.

btw, do they still have the curious effect that if you try to regas a bottle that already has the syrup in, it expands/explodes causing liquid to be expelled from various orifices of the machine? :)

[Anna Kettle]

Its a complete pain isnt it! I too far prefer using a Sodastream to carting bottles of water around and the cartridges are harder and harder to find though so far the Sodastream website has kept up to date with who is still supplying. Sodastream were taken over by their American competition a couple of years ago and I suppose they are trying to streamline the company

Anna

-- Anna Kettle Lime plaster repair and conservation Freehand modelling in lime: overmantels, pargeting etc Tel:    (+44)  01359 230642 Mob:   (+44)  07976 649862 Please look at my website for examples of my work at:

 

[Dave]

I have not read any answers to your post yet, but to comment on it.

All pipe fittings are standard, the only ones that are not are the ones that the stupid EU overtook. It was my privilege to work for BAe systems and the ejection seat bay had domestic CO2 in plenty and would fill a bottle up for 50 pence. It went to charity.

The measured pressure when a bottle is filled is useless. If you look at the bottle, you will find an empty and full weight. This takes into account the pressure and temperature of the bottle. Naturally, filling a bottle will raise its temperature. Raising the temp will raise the pressure and result in less gas than you thought you had bought.

[Dave]

Thanks for all that, but I will have to snip most of it.

Out of curiosity, what colour are the cylinders?

You forgot about large grindstones that could take a wall out.

The most dangerous gas I worked with was LOX

[marc]

What about a soda syphon if you just want fizzy wtare?

fizzy water cost 17p for two litres at Morrisons (value range), so other than the effort of lugging it home (not a greenie who is worried about food miles!) this seems like a cheap and easy solution

Marc

[John Stumbles]

Aren't CO2 bottles for MIG welding the same?

[Dave Liquorice]

"pub gas" cylinders are normally black with grey/cream top. Not that there is any particulary strict colour code for cylinders.

That's not a gas. B-) But yes you don't want to mess with LOX, though it's not the gas itself that is dangerous but what happens to other things when there is a lot of it about.

[Dave Liquorice]

Possibly. Some pub gases are mixtures of CO2 and N2 rather than pure CO2.

[woodygb]

CO2 Cylinders contain liquid and gas in a ratio of .... when FULL ...approx 2/3 liquid and 1/3 expansion gap @ room temp of 55 Bar. A Full 250 gram bottle Sodastream bottle contains 250grams of LIQUID CO2 approx 0.25 litre.

I'd not recommend replacing the std Sodastream cylinder with another type ... The Sodastream cylinder valve and pipework has ....due to the various orifice sizes...a low flow and the system is balanced around the "farting" pressure relief valves ability to exhaust more gas out than flows in, to much flow into the soda bottle and the relief valve won't be able to cope and the pressure could rise dangerously high.

Refilling a Sodastream bottle is fairly simple ...NEVER exceed the Gross weight stamped on the bottle.

[Calvin]

into other areas both for refilling and for alternative coupling. From that and other sources it appears that, yes, refilling is an option but that Sodastream go out of their way to make sure that the cylinder is a pain to refill and is certainly not refillable on a standard machine - they've even patented an anti-refilling valve! As far as I can see at the moment the refilling at home option would cost maybe =A340+ to set up and of course involve the hassle of refilling it myself every couple of weeks, possibly more as it's hard to get a full refill. Coupling a more standard, larger cylinder seems like a cleaner option in that a reasonably sized standard cylinder holds roughly 7 times more CO2 than a Sodastream cylinder so it would only need attention a couple of times a year. There is a company in the USA offering to make up a hose using a standard fitting at one end and the valve of a Sodastream cylinder at the other but for a price - $170 plus shipping etc. So my next step is to explore that option in the UK, maybe as a ready made hose if such exists or maybe as a bag of bits which I make up myself.

To answer Dave's question: The cylinders are greyish, "35 litres" (of fizzy water).

Once again, thanks everyone for your help and I'll get back here with a followup when I've succeeded (or failed!).

[woodygb]

Hi Calvin

The CO2 page linked to is mine.

Might I suggest removing the brass valve from an EMPTY Sodastream bottle and connecting that to a suitable pipe.

the valve neck thread is a std bsp size 3/8" as I recall.

Cheers Alan

[Alan Braggins]

[...]

Have a look at

[Andy Dingley]

Whilst hardly safe, diabatic generation of CO2 gas from a cylinder full of liquid isn't in the same league as knocking the end of an oxygen cylinder.

[Calvin]

something similar to what I intend which is reassuring.

I took my Sodastream unit apart last night to investigate its inner workings. What I found was that the cylinder is coupled to the pressure relief mechanisum by a very narrow plastic tube. My guess (and I'm hoping to go to my local BOC agent to discuss it later today) is that the nuts and olives holding the thin tube are of a standard size and I can simply couple a standard cylinder directly to the PRV/ bottle cap this way. The internals of the head mechanism are interesting and I'm not sure I fully understand them yet. There are two pressure releasing mechanisms. Both of them have a pin on top which releases their pressure just before the bottle is removed (as it is tilted for removal). One must be the pressure relief valve which limits the pressure in the water bottle and signals the end of the carbonation process. I can't work out what the other is for, they are definitely different "strengths" as they look physically different. My guess is that one is a long-stop safety mechanism to prevent disaster if the operating one fails closed.

[woodygb]

The nut thread is 1/8" bsp.

If the side handle is up ...no bottle in the machine ...then the relief valve is mechanically depressed and held open....safety feature.

Insert a bottle and close handle ...the bottle is raised and the neck top seals....plus the relief valve is mechanically released.

Depressing the top button pushes the pin valve in the co2 cylinder down releasing gas ....once pressure is reached the relief valve "farts " ....raise lever.

Sodastream patent.

Regards Woody Author of webpage:-

[Dave]

And here's me thinking there was :-) I must get out more.

LOL you don't have to tell me about that. Instant rusting of damp steel and huge explosions of other combustibles.

One gas (liquid) that I used to enjoy playing with was nitrogen :-)

Dave