# Bottling CO² Vol limits theory

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#### BasementArtie

##### Well-Known Member
The reboot is never as good as the original. And I know this has been asked so many times.

I'm here for a discussion about the following.

I kind of wish this subject had previously received a definitive answer to the question. (I think it's important to say I'm in the UK and have access to 33cl Belgians bottles as I hear American beer bottles can be paper thin).

First and foremost do not use anything I say within your bottling technique for priming calculations as this is only a theory which hasn't been tested at all, this is NOT guidance.

I'm sick of wondering what a bottle can hold CO² Vol wise and worrying what the tolerances, what the max would be and what's safe. Everyone says 2.5 vol.CO² is fine and 3 is the limit, that's not good enough for me.

Obviously the question is hard due manufacturing processes, shape of bottle, any damage, how many times a bottle has been reused (as I read something that the stress tolerance can be reduced by up to ~25% for bottle which are reused).

There was a thread on here previously in 2019 which sparked my interest which was looking at stubbie Belgian 33cl and 12oz bottle weight and the relationship to the pressure the brewers use within these styles. Light vs Heavy Glass, safe levels of carbonation

I was surprised the initial idea and analysis didn't take off and spark more discussion (may the same thing has been discussed in length else where).

As this thread was looking specifically at smaller bottles and seemingly came to the conclusion that the Belgian beer bottles use at least 65g+ for each Volume of CO² in a 33cl container, I wondered if the size of bottle should be including in the equation, as obviously the method of dividing co2/vol by the weight wouldn't work for larger bottles (500ml or 750ml) as these will obviously weigh more, but perhaps not in a linear relationship to size.

So I came up with the idea of adapting the equation to g/ml per Vol.CO² as you can see this is a mix of metric and imperial however it should work.

Disclaimer: this is for capped bottles (my Tripel karmeliet and St Bernardus corked and caged are 620-640g empty bottles which hold 3.5-4 vol.CO²).

I.E.

Orval beligan bottle weigh 354g but hold 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 ~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.

La Chouffe, St Feuillien, Duvel etc all use the same bottles, I've weighed them and range from 281 to 288g so at 284g Duvel is 4.25 in vol. Which is 0.202g/ml per Vol.CO².

St Bernardus, Gouden Carolus, 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+

This got me wondering if I could create a "rule of thumb" using this information that you potentially would want to keep the g/ml per Vol.CO² above 0.2 to keep things "Safe". This links to the previous thread and the value of 65g per vol of CO² for a 330ml bottle as 0.2x330ml = 66g per vol of CO².

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.

Using 0.2 as an arbitrary "safe" cut off would leave Orval's bottle to be max rated to 5.36 vol Co² and Westmalle would be 4.81 vol Co². Which seems reasonable as during transportation they would need to see increases in PSI caused by agitation and temperature increase.

Then as I was focused on extremely strong beligan bottles I wanted to see if it was possible extrapolate this to other bottles.

The new 450ml swing top green Grolsch bottle would be rated to 0.2 at 4.25 vols. (383g) and my home-brew-shop 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! "

Furthermore I 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 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.

I'd like to say the only times I've heard people discussing bottle bombs are 1)frozen beer 2) infection 3) bottling too early 4)overfilled and too hot (expansion) 5) pre-damaged bottles. It seems rare to over prime enough for smashing bottles and very anecdotal I know but it seem like people have pushed way above the upper limits of bottles without issue other than over-carbed beer i.e. 4-5.

Again I reiterate this is just a theory currently and I have done no testing so please do not use this as guidance as this can be dangerous. However I would like people's thoughts on the topic.

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If it fizzes, it's good to go...... Really overthinking things guy

Furthermore I 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
I would be inclined to just go with this guideline.

The NB list is close enough. I use 12 oz long necks for most beers carbed up to 2.8 vols or so; 16oz swingtops for higher volumes, like Weissbiers and some Belgians.

I would be inclined to just go with this guideline.
I would usually think this scale is fine as well, however some of the British (European) 500ml bottles weigh between 290-310g which I wouldn't want to really carb more than 2.9-3vols which is roughly the 0.2g/ml per Vol.CO² obviously if they were a bit heavier (and hopefully stronger) like some other British bottles then definitely the 3.5 would be fine.

Maybe I am over thinking it however I'd just like a rule of thumb which isn't just incredibly arbitrary.

Maybe I am over thinking it however I'd just like a rule of thumb which isn't just incredibly arbitrary.

This is HBT. We "overthink" a lot of things, and that's not a bad thing. It's probably more info than I need on bottles, but some people here appreciate a deep-dive into the topic.

I do agree that there are some variables at work. For instance, take the standard 12 oz long neck. They seem to be getting thinner and thinner. Conventional wisdom says they can handle 3 volumes, but I try to keep the maximum a little below that.

Another variable is temp. Carbing to the bottle's limit is one thing when the bottles are in the fridge and most CO2 is in solution, but a whole different thing when stored in a warm room. I like to bottle on the premise that it could be subjected to the worst-case situation. So far, no glass grenades for me.

I do agree that there are some variables at work. For instance, take the standard 12 oz long neck. They seem to be getting thinner and thinner. Conventional wisdom says they can handle 3 volumes, but I try to keep the maximum a little below that
Exactly, I completely agree that's some bottles of their individual size category (12oz, 330ml, 250ml, 450ml, 500ml, 750ml) are getting thinner and thinner.

I.e. you reference the 12oz bottles (355ml) being thinner and that you're reluctant to push up to the "limit" of 3 volumes suggested by NB. You settle for 2.8 or so. However, and for example using the 0.2g/ml per Vol.CO² a 12oz anchor brewing bottle you'd only be able to pressuring it to 2.71 Vol.CO² due to it's weight being 192g. Close to the 3 but not within my rule of thumbs "safe limit"

That being said NB has created an arbitrary cut off for each size bottle and I presume this accounts for all weights, manufacturing processes and shapes. However I doubt the limits they refer to are limits in the sense of catastrophic event if you go above these values. Obviously every bottle would need leeway to deal with the agitation and heat variability during transportation.

As I previously mentioned Duvel is rated to 0.202g/ml per Vol.CO² at 4.25vol 330ml and St Bernardus around 0.208 g/ml per Vol.CO² at 3.5vol for 330ml. I doubt they would leave no room for maneuver going above these valves as they transport their bottle worldwide obviously incurring significant agitation and heat swings, so again with my "safe" limit theory there would most likely be some leeway above this valves but it would be recommended to be the limit you actual target the bottle too if want to go high.

Take the Grolsch swing top as another example. These in the original post should theoretically be able to deal with 4.2vol.CO² at 20C (68F) which is 54.1 psi, however I've seen statements from Grolsch that their bottles will hold however the swinging cage will start to burp and leak around 70psi which would equate to the same bottle being heated to 30C (86F).

The information that norther brewer has given on limit values is great and all for most cases. However as you can see there could be bottles which rate lower and higher than this limit (not to say carbing them to these values would be unsafe as I've stated there is likely leeway here so safety reasons).

This leads me to think we should be taking every clean uncracked and unchipped bottle style (different size and shape) to be different and treat its limit as its own.

Of all the factors being considered regarding bottle strength, one might need to take into account whether the glass itself is made of recycled glass or virgin glass (waiting for the wise cracks).

Of all the factors being considered regarding bottle strength, one might need to take into account whether the glass itself is made of recycled glass or virgin glass (waiting for the wise cracks).
There is that bit of information floating around about a reduction in strength of reused bottles by 25% however I don't know if that refers to all glass bottles or ones made one way which are designed to be used once.

Keep an eye on Craigslist. You might find some vintage '70s returnable 12oz long necks. They usually come in heavy cardboard case boxes.

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