Pasteurization & pressure

[Rattertat]

Hey guys, once again a pasteuritation-related question!

It's been a while since I last posted - but my Cider turned out pretty good! I let it set for a couple of months and it's now crystal clear (which was my issue the last time I posted if I remember correctly).
It - unsurprisingly - turned out a little too tart when fully dry, so I added sugar to SG 1.010 for the taste and 16 g/l for carbonization and bottled it.
I've got an extra bottle with a manometer on top so I can monitor the pressure and the carbonization properly.
The pressure has now reached 2.8 bar at 20°C/68°F which should give me a co2 content of ~6,2 g/l or ~3,2 Volumes which should be about right for a sparkling semi-dry cider.

So the time has come to pasteurize.

Fortunately, I have access to a convectomat, as I'm a part-time chef, so I can go low and slow on the pasteurization and have control over the temperature. I also have a dummy-bottle filled with water and a thermometer inside, so I can monitor the temperature developement.
I also know how to compute PUs correctly.
The question that remains is concerning the pressure that will develope and whether bottles are gonna burst or crowncaps are gonna pop.
I'm planning to go no higher than 62°C/144°F.

Is there any way I can compute the pressure that's gonna develope inside the bottles? Couldn't find a table on this.
Is there any data on how much pressure a standard (new) 0.5l beer bottle can take before bursting? Or any data on how much pressure is gonna cause crowncaps to pop?
It wouldn't be dangerous if one exploded or a cap popped since I'm gonna pasteurize inside the convectomat but still - I don't wanna waste cider. If the pressure that developes is way too much I'd rather vent the bottles and re-cap them beforehands. But I don't wanna do that if it's not necessary.

Any insights or data on this is greatly appreciated!

Thanks!

Jannis

 

[Gnomebrewer]

There is most certainly data on how much CO2 your solution with hold at particular temperatures/pressures and how much your bottle will handle. The reality though (from my own and others experience - see the bottle pasteurising sticky) is that they WON'T EXPLODE if you haven't overcarbonated the bottles.

 

[Maylar]

2.8 bar (40.6 psi) @ 20 C (68 F) is about 3.4 volumes, which is high for a standard beer bottle even at room temp. At 144 F it'll be 104 psi (7.2 bar) and I don't think anything but champagne bottles will survive.

The formula is
P = -16.6999 - 0.0101059 T + 0.00116512 T^2 + 0.173354 T V + 4.24267 V - 0.0684226 V^2

Where P = pressure (PSI), T = temp (°F), and V = volumes of CO2.

When people pasteurize I recommend they stay below 2.5 volumes.

 

[Rattertat]

Thank you for the answers!

The formula you posted is really helpful.

I now put together a spreadsheet where I can easily compute all the numbers.

It get's confusing when you need to convert °F to °C, bar to PSI to atmospheres and co2 in g/l to volumes the whole time.

So I now found out that - with a carbonation level of 6.2 g/l or 3.2 volumes - I'll have a pressure of 6.7 atmospheres (98 PSI, 6.8 bars) at 62°C (144°F).

I've read in Claude Joliceurs book that standard beer bottles can handle a pressure of around 6 atmospheres.

So If I vent the bottles right before pasteurizing it should work out I guess.

 

[Maylar]

Just be aware that all bottles are not created equal. Some are thicker than others. Most sources say that a standard beer bottle will handle about 4 bar safely. Some of the Belgian beers are carbonated at 3.3 volumes, so pick your bottles carefully.

 

[Mike Contreras]

2.8 bar (40.6 psi) @ 20 C (68 F) is about 3.4 volumes, which is high for a standard beer bottle even at room temp. At 144 F it'll be 104 psi (7.2 bar) and I don't think anything but champagne bottles will survive.

The formula is
P = -16.6999 - 0.0101059 T + 0.00116512 T^2 + 0.173354 T V + 4.24267 V - 0.0684226 V^2

Where P = pressure (PSI), T = temp (°F), and V = volumes of CO2.

When people pasteurize I recommend they stay below 2.5 volumes.

Hello Maylar,

How did you derive the formula? I was going nuts trying to apply a formula that would help me with a problem similar to Rattertat.

Thank you for your help.

 

[Maylar]

Hello Maylar,

How did you derive the formula? I was going nuts trying to apply a formula that would help me with a problem similar to Rattertat.

Thank you for your help.

Copied it from here:

http://brainlubeonline.com/GasLawsBeer.html

 

[bkvanbek]

Wow, I didn't even try to follow the math. But I do carbonated mead, cyser and blends then stove top pasteurize them. Probably 20 batches, when I bottle I fill a plastic Gatorade 7/8ths full at the same time, and check it daily for how hard it is. When it feels right I but the bottles in large turkey fryer pot, with the strainer in to prevent the bottles from touching the sides and I bring it up to 145 degrees F for 30 minutes and then let cool. I takes a long time, but less explode than trying to do it fast.