Force carbonating.

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woody1959

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What exactly is it? and how do you do it, lets assume 20L cider, a 19L corny keg with sodastream co2
 

Graz

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What exactly is it? and how do you do it, lets assume 20L cider, a 19L corny keg with sodastream co2
Well for a starters you're not going to get 20L of cider into a 19L Corny ;)

It's a fairly straightforward process though, you put your cider (or beer) into the Corny, no priming sugar, only CO2 will be used to make it fizzy. Pressure and purge the Corny a few times and make sure the lid is sealed. Then there's two methods depending how quick you want to be drinking the stuff but in either case getting the Corny (and it's contents) as cold as possible is advantageous as the colder stuff is the more readily it absorbs CO2. The slow method is known as set and forget, you set you regulator to the desired carbonation pressure, leave it for a couple of weeks and it will carb up. You can then start drinking. The pressure depends on what how fizzy you want it and the temperature, see here: https://www.brewersfriend.com/force-carbonation-chart/

The other method involves lying the keg on its side with the gas in post on the top, pressurising to what's usually a slightly higher pressure than the desired final pressure and then rocking the keg to get the liquid to absorb the CO2. There's some good YouTube videos on this but you'll have to Google.

I noticed you said Sodastream for the gas though, force carbing can use up quite a bit of gas so seriously consider getting a pub cylinder if this is something you want to do in the long term, it will save you loads of money on refills anyway.
 

woody1959

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Well for a starters you're not going to get 20L of cider into a 19L Corny ;)
I know this :tongue:
That's what I am brewing, but I will only empty the fermenter down to tap level so I reckon about 15L gets transferred.
 

woody1959

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I noticed you said Sodastream for the gas though, force carbing can use up quite a bit of gas so seriously consider getting a pub cylinder if this is something you want to do in the long term, it will save you loads of money on refills anyway.
Just checking if I need to buy another regulator for pub cylinders as I am not sure my current one will work with them.
 

phildo79

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I will only empty the fermenter down to tap level so I reckon about 15L gets transferred
That's going to leave a lot of head space. Now I don't think that's an issue if you're force carbing but it would be if you were priming the batch.
 

phildo79

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Because of head space. If you brew a perfect 19L and plan on bottling it, you will add a certain amount of sugar to batch prime. About 3/4 cup is normal. But if you keg it, you would add less. This is due to overall head space. If you only fill your keg to 15L, that's leaving a lot of head space. Makes sense that you would need more sugar to compensate.

But I could be way off with that. It just seems logical.
 

woody1959

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Because of head space. If you brew a perfect 19L and plan on bottling it, you will add a certain amount of sugar to batch prime. About 3/4 cup is normal. But if you keg it, you would add less. This is due to overall head space. If you only fill your keg to 15L, that's leaving a lot of head space. Makes sense that you would need more sugar to compensate.

But I could be way off with that. It just seems logical.

The headspace will be filled with CO2 under pressure, probably about 20psi.
 
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phildo79

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Yes, and with force carbing, I imagine there isn't an issue because co2 is constantly being pushed into the keg. With batch priming however, only so much co2 is created by a particular volume of sugar. More head space would mean more co2 wouldn't be absorbed into the fluid. Just something to note for future brews.

I am very much in favour of letting the sugar do the work, so long as you don't plan on drinking the beer / cider for about a week. But I wouldn't use sugar if I was only partially filling the keg, for the aforementioned reasons.
 

woody1959

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Just to test stuff out I filled the corny with 18.5 ltrs of water (actually I stood it on scales and filled it with 18.5kg of water) and charged it up to 20PSI.
After 12 hours the PSI had dropped to 5 so I charged it up again to 20 and over night it dropped to 10 psi.
So my question is..as the CO2 is being dissolved into the water does the pressure drop, or do I have a leak?
 

phildo79

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Sounds more like a leak. I sometimes leave the gas connected overnight (sometimes on purpose, sometimes not) and don't think I have ever experienced what you have described.
 

woody1959

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Well this morning it's still at 20psi, so either it's a leak that's fixed itself or the pressure drop was because the CO2 is dissolving into the water.
 

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@IainM's right. You're making fizzy water. You'll see the same effect if you turn the gas off while your beer is force carbonating - don't though because the corny lids need some pressure to seal properly.
 

woody1959

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I just drew off a pint glass, added some sodastream lemon and lime syrup and it was quite a nice refreshing drink.

As the water was quite fizzy I am sure the pressure drop was because the CO2 is being absorbed into the water.
 

peebee

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Just checking if I need to buy another regulator for pub cylinders as I am not sure my current one will work with them.
Don't think anyone answered this?

But the regulator probably has an adapter to fit it to a Sodastream cylinder. That adapter may be marked? A UK Pub cylinder has a thread with a long descriptor (multiple compatible threads), but the bit often picked out is "W21.8". So that's what you want to see on the regulator's adapter (be warned; some regulators are foreign imports, States usually, and don't fit UK Pub bottles) - if the regulator's adapter is "W21.8" one side (the kooky trapezoid thread on the other to fit Sodastream), remove the adapter and screw the regulator directly onto the Pub bottle. Don't worry about pressures, it's liquid CO2 and is the same pressure whatever the size of cylinder.

… As the water was quite fizzy I am sure the pressure drop was because the CO2 is being absorbed into the water.
That's right. If you put in 2 BAR (2x atmospheric pressure or near 30psi) of CO2 that's about 5L of gas (21L total Corny capacity less 18.5L of water, x2) that will gradually dissolve into the water. To be significantly fizzy the water needs about 2 volumes of dissolved CO2, or (18.5 x 2) 37L. 37 - 5 = 32; keep adding the CO2 (or just leave the regulator and cylinder connected, but be sure of no leaks).

As a side-line: That was 30 psig that was added where "g" can mean "what the gauge tells you". It will actually be nearer 45psi (absolute pressure; i.e. compared to a vacuum).
 
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woody1959

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That's right. If you put in 2 BAR (2x atmospheric pressure or near 30psi) of CO2 that's about 5L of gas (21L total Corny capacity less 18.5L of water, x2) that will gradually dissolve into the water. To be significantly fizzy the water needs about 2 volumes of dissolved CO2, or (18.5 x 2) 37L. 37 - 5 = 32; keep adding the CO2 (or just leave the regulator and cylinder connected, but be sure of no leaks).
That's the information I needed, thank you, however by trial and error I have already discovered this.

As for the other question about connecting pub gas, it looks like I probably could but I strongly suspect if I did my poor little regulator couldn't handle it. ( that said, isn't all CO2 the same pressure? so if it can handle my sodastream gas it can handle a pub gas cylinder)

I'll stick with sodastream gas for now as pub gas doesn't actually work out that much cheaper.

Adams gas want £55 deposit, then £20+ vat for a refill and £12.50 + vat to deliver, they only deliver one day a week

When they deliver I have to pay another deposit and then my first deposit gets refunded when the 1st cylinder is back at their depot. So that's nearly £40 for a refill plus a rolling £55 they hold, and £40 gets me 3 sodastream refills from sodastream.
 
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