Light vs Heavy Glass, safe levels of carbonation

[luckybeagle]

I know this topic in general has been covered extensively, but I can't seem to find anyone discussing safe levels of carbonation by volumes relative to glass weight. The most I've seen is "use heavy Belgian bottles" and "stay away from paper thin Sam Adams bottles." And "2.5 volumes is safe." As a rule of thumb, I get it, but those explanations just lack the detail that I feel I need for the styles of beers I like to brew.

The discussions regarding bottle integrity and maximum volumes seem to center on the argument that "bottles will hold X volumes of CO2... until they don't."

That's a fair statement to make, however commercial and Belgian/Trappist brewers deliberately choose bottles that will hold their bottle conditioned and carbonated beer safely... indefinitely. They must have some idea, and not just through trial and error, of what their bottles can reliably hold.

I weighed my personal collection by stye and have come up with the following:

• Ninkasi/Deschutes/Hop Valley "Craft Beer" long necks and stubbies: 197 grams each
• Home brew supply store and miscellaneous thicker longnecks: 230 grams each
• Trappist Rochefort: 241 grams each
• Chimay: 271 grams each
  
• La Chouffe: 284 grams each
• Westmalle: 314 grams each
• Orval: 354 grams each

**IMPERFECTIONS AND INFECTIONS ASIDE**...

We know Orval holds 5 volumes via BLAM. Is there a crude relationship between weight and maximum volume? If Orval can hold 5.0 volumes and the bottles weigh 314g, can one assume that 354/5 = 70.8 grams of glass per volume CO2 for a ~12 oz bottle is "safe?"

I regularly use my Ninkasi bottles for my 3.0 volume Belgian Blondes and Tripels. No bottle bombs yet. At 197g per bottle, it's 197g/3 = 65.6 grams of glass per volume. I wonder what level takes them outside of safe territory?

Westmalle bottles are carbed up to 4.0 volumes for some of their styles: 314/4 = 78.5g of glass per volume. Since Westmalle bottles are used in several Trappist breweries, it's possible these are made thicker to accommodate more bubbly brews.

Not sure on La Chouffe or Chimay's carbonation levels, though La Chouffe (284g) uses the same bottles as Duvel (4.25 volumes, CO2), which would be 284/4.25 = 66.82 grams of glass per volume.

Rochefort is carbed to about 3.5 volumes in 241 gram bottles. 241/5= 68.85 grams of glass per volume.

To me it seems a trend is being established: roughly 65 to 75g of glass per volume of CO2 seems to be safe, with most being on the low end of that range.

I am pushing the limit with the 197g craft beer bottles on a 3.25ish Dubbel that I just bottled 1 week ago. I split that batch between 197g glass and 230g glass. If any burst, I will report back. If any of my 230g glass blows but my 197g glass doesn't, I'll be confused/won't be able to draw a conclusion/correlation.

If anyone has thoughts, experiences, further knowledge or opinions on glass integrity, please share!

 

[RPh_Guy]

You're forgetting two huge variables:

1. Temperature
2. Agitation

These factors greatly affect pressure and therefore the maximum "safe" CO2 volumes.

One more thought: it makes sense that the bottle shape would come into play and not just the weight.

Good luck in your quest for a definitive answer!

 

[luckybeagle]

Thanks kindly. I have a question on that, as I am still trying to understand carbonation: wouldn't 3 volumes, for instance, be 3 volumes? E.g. if I bottled a beer at room temperature, carbed it to 3 volumes for 2 or 3 weeks, and then put them in the fridge, or kept at a stable 70F, wouldn't there be 3 volumes worth of CO2 in that bottle (a closed environment)? I know Co2 is absorbed in liquid more readily under cold temperatures, but whether or not those 3 volumes are fully in the beer or fully in the headspace, wouldn't the bottle be under the same internal pressure? I'm asking because I really don't know and would love to hear some thoughts on that.

I thought about the shape, too, especially after gawking at the seductive curves of the Orval bottle. Such a sexy and mysterious bottle (#heavybreathing, lol). My method/logic isn't lab sound, but if there is a general rule of thumb that goes farther than the commonly accepted logic of "pry top bottles hold 2.5 vols safely," when a lot of home brewers exceed that by quite a bit (either on purpose or by accident), such as one that can be based on weight of glass for standard 11.2 to 12 oz shapes, I think that could be a pretty useful thing. If 65g per volume can be a good rule of thumb for safe levels of carbonation on undamaged, uninfected 12 ounce bottles at room or fridge temps, that would be pretty cool to know.

Hmm...

Tonight's folly:

 

[S-Met]

I think that bottles that hold more pressure are heavier, but heavy bottles are not all high pressure. Be careful using weight alone.

Are there any markings on the bottoms?

 

[RPh_Guy]

whether or not those 3 volumes are fully in the beer or fully in the headspace, wouldn't the bottle be under the same internal pressure?

Nope. Calculators for this are widely available.

2.5 vol @ 65°F = 26 PSI
2.5 vol @ 85°F = 38 PSI

3.5 vol @ 65°F = 41 PSI
3.5 vol @ 85°F = 56 PSI

Elevation and volume of headspace also affect pressure, besides temperature and agitation.

I think bottles hold a lot more pressure than people give them credit for holding. Many cider makers heat pasteurize the bottles, bringing them to somewhere around 70-105 PSI (yes, there are some explosions but mostly not, and they are probably being agitated during the process which further increases the pressure). Therefore it's probably safe to hit up into the low 4s and if you don't heat or agitate the bottles it'll be perfectly fine with even regular bottles.

If you want to test your bottles, you can do it at home, if you don't mind the high explosion risk.
Carbonate one to the particular CO2 volume you want to test. Heat it in a water bath to the maximum temperature it could reach during storage, transportation, and handling, and then put it in a closed plastic tub (you should probably tape the lid) and tilt the tub to roll it around to see if it explodes. Don't open it to look unless you want glass shards in your eyes.

 

[william_shakes_beer]

I researched this issue a bit a few years ago. Believe it or not, standard 2L soda bottles are rated to a higher pressure than glass beer bottles. I was concerned because I packaged a batch or cider in 2L soda bottles and they began bloating. I'm not talking ultimate burst strength, but rated working pressure, Plastic just gets more attention because it looks like a pregnant worm when the pressures climb. Bottles look the same right up- until the time they shatter and send shrapnel flying through your limbs. FWIW, I have been brewing for several years and the only container that has burst was a glass bottle I used to package a batch of root beer. IMHO., so long as you follow directions carefully, maintain a sanitary wort, and ensure primary fermentation is done before you bottle, you should have no real issues.

 

[BasementArtie]

The reboot is never as good as the original.

I kind of wish this thread got to the bottom of the question. As I'm wondering the same. I'm surprised after your initial analysis nobody else put in any kind of input.

I'm wondering if size of bottle should be including in the equation as obviously your method of dividing co2/vol by the weight was in reference to 330ml bottles. However this would differ if you were to use 500ml or 750ml bottles as this will obviously weigh more.

g/ml per Vol.CO²

I.e. Orval weighs 354g but holds 330ml so 354g/330ml = 1.073g/ml then divide by the pressure used in the bottle so 5 = 0.215g/ml per Vol.CO²

Likewise this would mean Westmalle at 4 Vol.CO² and the bottle is (my weight 317g) would be equal to 0.240g/ml per Vol.CO²

Then let's say I want to pressure my 750ml Belgian flip top of course with a Tripel inside which weighs 533g to 3.5 Vol.CO² this would be 0.203g/ml per Vol.CO²

Which would pretty identical to what a 330ml Rochefort bottle would be rated to at 3.5 Vol.CO² 0.207g/ml per Vol.CO².

I wonder if this would be a decent rule of thumb that you want to keep the g/ml per Vol.CO² above 0.2 to keep things "Safe". Obviously again this isn't taking into account shape of bottle or manufacturing processes or storage temp or agitation but what rule of thumb can account for every confounder.

 

[BasementArtie]

Just done a bit more calculation. And I have to clarify I think this should be for crown capped bottles not corked as my 75cl Tripel Karmeliet bottles are heavy as ****.

You said you use those Ninkasi brewing company bottles. I think you're referring to the 12oz one which are not 330ml, they're 354.882ml.

At 3.0vol this would be 0.185
At 3.25vol this would be 0.171
As you've had luck with both of these pressures I would suggest that the actual tolerances on bottles are much higher than we think however 0.2 should still be seen as a safe limit. Which would equate to 2.77vols.

Like wise using the 0.2 limit Orval would he rated to 5.36 vol Co² and Westmalle would be 4.81 vol Co². However like said that could in fact be much higher.

Also like you say la Chouffe, St Feuillien, Duvel etc all use the same bottles and I've weighed them and range from 281 to 288g so at 284g Duvel is 4.25 in vol. Which is 0.202 again above the 0.2 "safe" limit and close to Trappist Rochefort and my 75cl Belgian bottle at 3.5 vol.

St Bernardus and Delirium (other than the grey flecked paint) use the same bottles as Rochefort judging by shape and weight. 241-246g and likely from what I can find Carb to 3.5vols. which again is 0.2+

Just for reference the new 450ml swing top green Grolsch bottle would be rated to 0.2 at 4.25 vols. (383g) and my home-brew-shop (brew2bottle) swing top bottles 500ml (454g) would be 4.54 vol. for 0.2. I've questioned the shop I bought the homebrew ones from what they are rated to and they openly admitted they didn't know however they said that they haven't ever had bottle bombs using these (themselves and customers) and people buy them for mead rated higher in CO² Vol than beer and he was so confident he said "I will give you my word that they should be fine & any issues you can come back to hunt me down! "

 

[BasementArtie]

It have attached a file from Northern Brewer they state Max to be the following.

BOTTLE:VOLUME CHART
Bottle size | Max Vol. CO²
12oz. 3
33cl Belgian 3.5
500ml European 3.5
Swing top 4
Champagne 7
PET 10

Which kind of fits in.

Take a 12oz bottle to weigh ~200g (like the one you used) would be maxed ~0.20g/ml per Vol.CO² at 3vol.

33cl Belgian if they were using the Trappist Rochefort / St Bernardus / Gouden Carolus / Delirium as they example this would be ~241g which would work out at ~0.209g/ml Vol.CO² at 3.5vol.

500ml European bottles vary a lot (from 300g to 450g) depending on style, however I would say 350g is roughly about right. Which would calculate at exactly 0.2g/ml Vol.CO² at 3.5vol.

Swing tops, the two I've already mentioned are 383g at 450ml and 454g at 500ml which work out at 4+ (4.2 and 4.5vol respectively) at 0.2g/ml Vol.CO² (I don't know if US Swingtop are lighter than the Grolsch style, if so this may attribute to the 4 Max rating, however 4 is still high)

Champagne bottles can be from 750-900g per a bottles and are 750ml. Using 900g this according using 0.2g/ml per Vol.CO² would only allow for a Max of 6vols. Either champagne bottles use better glass and design than beer bottles to hold higher CO² volumes or the 0.2 estimate is conservative as at Northern Brewer's 7 max figure this would be 0.17g/ml per Vol.CO² for a 900g bottle and even lower still for a 750g bottle at 0.143g/ml per Vol.CO².

 

[luckybeagle]

This is all great information, BasementArtie--I must've missed the alert in my e-mail about this thread being updated. Just wanted to briefly acknowledge your research while I'm at work and intend to pore over your data this evening!