Solid Bung Cold Crashing Tonight!

[Siiteri]

First try with this vessel. (6 gal thin neck glass carboy)
Wish me luck friends! Hope I don't wake up to a boom and a mess!

Also, has anyone had this go wrong? I've read up quite a bit online and can only find accounts of people not willing to risk the implosion and accounts of people who have always solid bung'd. I couldn't find anyone who reported an actual implosion haha. I partially posted this so it could join the documentation of solid bung glass vessel cold crashing after all the research I've done on the topic.

My amazing room mate estimated the volume of the gas at the top of my fermenter as a cone, its got .001473m3 space. And if you put that much space through the ideal gas law equations for a temp change of 68f to 46f the psi change is only ~0.488. Since my fermenter lid is less volume than its conical estimation, it's actually even less pressure. The write up is attached as a file.

I believe the thin neck of my fermenter will be more than sturdy enough to withstand a negative change in pressure of 0.5 psi. I'll report here tomorrow how it all works out.

Next Day Update: No implosion! Woo! I will be doing this again in the future. If you vote yes on having an implosion can you specify when the implosion happened? Like if it was while you were moving the vessel w/ negative pressure?

 

[Jayjay1976]

The entire vessel will be subjected to that pressure, not just the area of headspace. The overall strain on the glass walls isn't the problem, its the areas where glass transitions from thick to thin where stresses wihin the glass become magnified. Will you be lifting or moving it about under partial vacuum? A calculated risk is nonetheless a risk. Good luck.

 

[Siiteri]

The entire vessel will be subjected to that pressure, not just the area of headspace. The overall strain on the glass walls isn't the problem, its the areas where glass transitions from thick to thin where stresses wihin the glass become magnified. Will you be lifting or moving it about under partial vacuum? A calculated risk is nonetheless a risk. Good luck.

That's good info to know! No, no moving or lifting. The bung will be removed in it's current position in the kegerator. If it isn't sucked in that is. It has got a lip on the top to prevent that, but I could see a chance of it bending a little to sneak through.

 

[Siiteri]

No implosion! Hope this reassures some people considering this option in the future. Ofcourse there is awlays a risk invloved. Especially if your vessel has had micro fractures from previous impacts.

 

[day_trippr]

So what happens when you remove the bung from a carboy with a cold-induced vacuum within?

 

[TechFanMD]

So what happens when you remove the bung from a carboy with a cold-induced vacuum within?

The same thing that would have happened if the bung were left off - air goes in...just all at once instead of gradually. I fail to see the point of risking the bung at all really. I'd be more tempted to try a large balloon or something.

That said, I used to degas wine with a bung with a nipple in the hole and pull a vacuum on it with my Foodsaver. I did this even with smooth walled (thin) carboys and never had an issue. I'm older and wiser now and might not risk it - at least not pull as much vacuum as I used to, but it is probably pretty safe with cold crashing pressures. If the bung gets pulled in it's game over for that carboy (unless you don't mind it being in there I guess).....though air getting in is the end result either way so whats the point?


But...the OP only said 46F, which I wouldn't even consider to be cold crashing. I've never heard of anything over 40F being considered cold crashing, and I think most people use 38F (since many have a fridge/keezer already set at 38), some go down to 33F.

 

[Calder]

Glad to hear nothing happened. For completeness, you should also calculate the change in volume of the beer vs the change in volume in the glass carboy.

I think you will find the beer will reduce in volume a lot more than the glass carboy increasing the negative pressure.

 

[TechFanMD]

Glad to hear nothing happened. For completeness, you should also calculate the change in volume of the beer vs the change in volume in the glass carboy.

I think you will find the beer will reduce in volume a lot more than the glass carboy increasing the negative pressure.

I had the same gut feeling and was going to post that as well.....but I calculated it and either my math is wrong, or 5 gallons will only experience a few hundredths of a cublic centimeter of volumetric contraction for the whole 5 gallons even going from 68-40F.

 

[isomerization]

I had the same gut feeling and was going to post that as well.....but I calculated it and either my math is wrong, or 5 gallons will only experience a few hundredths of a cublic centimeter of volumetric contraction for the whole 5 gallons even going from 68-40F.

I’m guessing he used ideal gas laws to calculate the change? Looks like 68-40F would cause an ideal gas to decrease in volume by about 0.4 gallons. Liquids are another story (coefficient of expansion needed).

 

[Siiteri]

Thanks for all the replys y'all!

So what happens when you remove the bung from a carboy with a cold-induced vacuum within?

Oxygen is introduced again, but I quickly blow it off with co2 after kegging. So it's far less oxygen exposure than letting it sit for 2 days.

The same thing that would have happened if the bung were left off - air goes in...just all at once instead of gradually. I fail to see the point of risking the bung at all really. I'd be more tempted to try a large balloon or something.

That said, I used to degas wine with a bung with a nipple in the hole and pull a vacuum on it with my Foodsaver. I did this even with smooth walled (thin) carboys and never had an issue. I'm older and wiser now and might not risk it - at least not pull as much vacuum as I used to, but it is probably pretty safe with cold crashing pressures. If the bung gets pulled in it's game over for that carboy (unless you don't mind it being in there I guess).....though air getting in is the end result either way so whats the point?


But...the OP only said 46F, which I wouldn't even consider to be cold crashing. I've never heard of anything over 40F being considered cold crashing, and I think most people use 38F (since many have a fridge/keezer already set at 38), some go down to 33F.

I'm going to quickly blow off the O2 that comes in with CO2 after kegging. I did it to 46 as thats the highest temp my kegerator would go to and I wanted to be safe about it, I did a full cold crash to 36 in the keg.

Glad to hear nothing happened. For completeness, you should also calculate the change in volume of the beer vs the change in volume in the glass carboy.

I think you will find the beer will reduce in volume a lot more than the glass carboy increasing the negative pressure.

We did do the math on that but like others said, it seemed to be pretty negligble. Maybe we did the math wrong but that was only going to change like 0.05-0.15 psi at the most. I think it came out to something like 15mbar change due to the volume of the beer reducing from room temp to 46.

I’m guessing he used ideal gas laws to calculate the change? Looks like 68-40F would cause an ideal gas to decrease in volume by about 0.4 gallons. Liquids are another story (coefficient of expansion needed).

Yeah there's an image linked with the original post that shows the calculations made. First we estimated the volume of the top of my fermenter as a cone, then used the difference of ideal gas laws to calculate the pressure change.

 

[Siiteri]

The entire vessel will be subjected to that pressure, not just the area of headspace. The overall strain on the glass walls isn't the problem, its the areas where glass transitions from thick to thin where stresses wihin the glass become magnified. Will you be lifting or moving it about under partial vacuum? A calculated risk is nonetheless a risk. Good luck.

Were you moving your vessel when it failed?

 

[day_trippr]

The same thing that would have happened if the bung were left off - air goes in...just all at once instead of gradually. [...]

Totally a rhetorical question...

 

[Jayjay1976]

Were you moving your vessel when it failed?

I was only thinking about moving it when it failed.

 

[ba-brewer]

where is a trick to remove a bung from a carboy
https://www.homebrewtalk.com/forum/threads/lost-stopper-in-carboy.135846/#post-3048185

 

[Blazinlow86]

I used a solid stopper as you described when cold crashing on my hand-me-down glass carboys over 50 brews in a row and they were all double/triple batches so 2/3 carboys a brew. I never had anything break or even had a bung sucked back in. There would always be suction when the bung was removed which of course is somewhat counter productive o2 wise but I would only remove the bung immediately at racking then pressure transfer using the orange carboy cap/racking arm without ever moving the carboy and then purge again once in the keg. It wasn't perfect and I got tired of dealing with multiple vessels and glass so I upgraded to a unitank. That being said I'm sure its somewhat risky and can break. Just my experience. Cheers

 

[Siiteri]

I used a solid stopper as you described when cold crashing on my hand-me-down glass carboys over 50 brews in a row and they were all double/triple batches so 2/3 carboys a brew. I never had anything break or even had a bung sucked back in. There would always be suction when the bung was removed which of course is somewhat counter productive o2 wise but I would only remove the bung immediately at racking then pressure transfer using the orange carboy cap/racking arm without ever moving the carboy and then purge again once in the keg. It wasn't perfect and I got tired of dealing with multiple vessels and glass so I upgraded to a unitank. That being said I'm sure its somewhat risky and can break. Just my experience. Cheers

Thanks for sharing!