I have managed to get some information from a few manufacturers about the pressure limits of their bottles.
This information seems worth sharing as heat pasteurising and the risk of bottle bombs seems to be a frequent topic. So here is what I have found... use the information to help make your own decisions about how far to go down the bottle bomb path.
Visy Glass (one of Australia's large.. glass bottle manufacturers) says...
With our bottles, we typically talk in GV (Gas Volume). Gas Volume is a unit less measure, of how much C02 is present vs liquid.
Ciders are typically less than 3GV (Gas Volume) and sometimes up to 4GV, which results up to 12Bar or 1.2MPa. Our industry beer bottles are typically rated to 4GV; Product Results
We do not recommend reusing one-way bottles for home brewing, and when using new bottles or even returnable bottles in good condition, they should not be filled beyond the rated capacity.
ShangHai Misa Glass Co. Ltd. Beer Glass Quality Standards refer to GB4544 (a China Standard). I have mentioned this in other posts but following is an extract from the Misa web site...
1, internal pressure.
The internal pressure resistance item is one of the most important safety indicators for beer glass bottles. Due to the filling of beer with a certain amount of CO2.therefore,Beer bottle as a beverage bottle filled with CO2 should strictly meet the internal pressure requirements specified in GB4544.The current standards in China stipulate that the qualified product index is ≥1.2 MPa(all developed countries are ≥1.6 MPa,Japan International Standard is 1.8MPa), otherwise,Due to the lack of internal pressure resistance of beer glass bottles,Will cause beer glass bottles to fill,transport,In the process of consumption, there was a bottle burst accident.
The inspection data shows that the qualified rate of the internal pressure resistance of recycled beer glass bottles was 25% lower than that of new beer glass bottles and selective beer glass bottles.
I found some manufacturers who have published the pressure ratings for a limited number (but not all) of their bottles so I looked for any relationship between the weight and capacity of bottles vs pressure rating. This information is attached and as expected, does show a rough relationship but the individual bottle rating is probably more important.
I guess the most relevant information from all of this is that new 330 ml or 12 oz bottles (commonly used by many of us) seem to be rated by manufacturers at 4 volumes of CO2 which is only 0.36 MPa (52psi) at room temperature of 20C/68F. However if a bottle carbonated to 4 volumes of CO2 is heat pasteurised to something like 65C/149F, the pressure will reach 1.26 MPa (183psi) which is at the limit of the bottle rating and getting into "Bottle Bomb Land".
So, if recycled bottles are being used and downgraded by 25% as recommended by Misa Glass, it seems that carbonating to 2.5 volumes is about as far as it is prudent to go for heat pasteurising. The recycled bottle downgraded rating would now be 0.9MPa (135psi) and the pressure at 65C/149F will approach 0.75MPa (109psi). This seems to be a reasonable margin of safety.
Similarly, bottling for a still sweet cider at around SG1. 015 would generate the same sort of pressure (0.75MPa or 109psi) if left to fully ferment, and certainly approach volcano or "Bottle Bomb Land" if the bottles were left in a warm room of say, 30C/86F.
Hmm, food for thought.
This information seems worth sharing as heat pasteurising and the risk of bottle bombs seems to be a frequent topic. So here is what I have found... use the information to help make your own decisions about how far to go down the bottle bomb path.
Visy Glass (one of Australia's large.. glass bottle manufacturers) says...
With our bottles, we typically talk in GV (Gas Volume). Gas Volume is a unit less measure, of how much C02 is present vs liquid.
Ciders are typically less than 3GV (Gas Volume) and sometimes up to 4GV, which results up to 12Bar or 1.2MPa. Our industry beer bottles are typically rated to 4GV; Product Results
We do not recommend reusing one-way bottles for home brewing, and when using new bottles or even returnable bottles in good condition, they should not be filled beyond the rated capacity.
ShangHai Misa Glass Co. Ltd. Beer Glass Quality Standards refer to GB4544 (a China Standard). I have mentioned this in other posts but following is an extract from the Misa web site...
1, internal pressure.
The internal pressure resistance item is one of the most important safety indicators for beer glass bottles. Due to the filling of beer with a certain amount of CO2.therefore,Beer bottle as a beverage bottle filled with CO2 should strictly meet the internal pressure requirements specified in GB4544.The current standards in China stipulate that the qualified product index is ≥1.2 MPa(all developed countries are ≥1.6 MPa,Japan International Standard is 1.8MPa), otherwise,Due to the lack of internal pressure resistance of beer glass bottles,Will cause beer glass bottles to fill,transport,In the process of consumption, there was a bottle burst accident.
The inspection data shows that the qualified rate of the internal pressure resistance of recycled beer glass bottles was 25% lower than that of new beer glass bottles and selective beer glass bottles.
I found some manufacturers who have published the pressure ratings for a limited number (but not all) of their bottles so I looked for any relationship between the weight and capacity of bottles vs pressure rating. This information is attached and as expected, does show a rough relationship but the individual bottle rating is probably more important.
I guess the most relevant information from all of this is that new 330 ml or 12 oz bottles (commonly used by many of us) seem to be rated by manufacturers at 4 volumes of CO2 which is only 0.36 MPa (52psi) at room temperature of 20C/68F. However if a bottle carbonated to 4 volumes of CO2 is heat pasteurised to something like 65C/149F, the pressure will reach 1.26 MPa (183psi) which is at the limit of the bottle rating and getting into "Bottle Bomb Land".
So, if recycled bottles are being used and downgraded by 25% as recommended by Misa Glass, it seems that carbonating to 2.5 volumes is about as far as it is prudent to go for heat pasteurising. The recycled bottle downgraded rating would now be 0.9MPa (135psi) and the pressure at 65C/149F will approach 0.75MPa (109psi). This seems to be a reasonable margin of safety.
Similarly, bottling for a still sweet cider at around SG1. 015 would generate the same sort of pressure (0.75MPa or 109psi) if left to fully ferment, and certainly approach volcano or "Bottle Bomb Land" if the bottles were left in a warm room of say, 30C/86F.
Hmm, food for thought.
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