[Richard]

Buy a Speidel. You can seal it and plastic will absorb the pressure change.
Beer will oxidize significantly if left exposed to air,  but it is up to each brewer to decide how important this is.

Sent from my SM-G960U using Tapatalk

Or ferment in a corny

Neither of these comments is very helpful. It is like if I asked advice about procedures for changing the oil in my car and you told me to buy a Tesla.

[Robert]

Buy a Speidel. You can seal it and plastic will absorb the pressure change.
Beer will oxidize significantly if left exposed to air,  but it is up to each brewer to decide how important this is.

Sent from my SM-G960U using Tapatalk

Or ferment in a corny

Neither of these comments is very helpful. It is like if I asked advice about procedures for changing the oil in my car and you told me to buy a Tesla.

But you have yourself given a well thought out analysis of the relative challenges of balloons and jiggling.  If you report the results of your try at jiggling, you might just  provide the answer yourself,  for you and everyone else who's not in the market for a Tesla.

[lupulus]

Buy a Speidel. You can seal it and plastic will absorb the pressure change.
Beer will oxidize significantly if left exposed to air,  but it is up to each brewer to decide how important this is.

Sent from my SM-G960U using Tapatalk

Or ferment in a corny

Neither of these comments is very helpful. It is like if I asked advice about procedures for changing the oil in my car and you told me to buy a Tesla.

The first lesson I learned when asking for advice in forums is to remember that people take a few minutes out of their busy schedules to lend a helping hand the best way they can.
I wish you the best of luck with your jiggling.

Sent from my SM-G960U using Tapatalk

[scrap iron]

I tried the balloon thing a couple of times and it collapsed. I think I put it on too late. So I tried a looped blow-off setup. It was a 5 foot long blow-off tubing I put a loop in the middle and suspended the loop from the top of my fermenter fridge. The end I put into a bottle of cheap vodka that I use for air locks. Crashed from 68* to 50* over 24 hrs and the vodka never got past the loop. This is the first time I've tried this  and it seemed to work. Should not have sucked back anything but co2 and if it does it would be just a little vodka.

[The Beerery]

if it does it would be just a little vodka.

And oxygen.

[scrap iron]

[/quote

if it does it would be just a little vodka.

And oxygen.

Why is that, should have been co2 in the line at the start of the crash? Unless there is oxygen in the vodka, but like I said none made it to the fermenter.

[goose]

Buy a Speidel. You can seal it and plastic will absorb the pressure change.
Beer will oxidize significantly if left exposed to air,  but it is up to each brewer to decide how important this is.

Sent from my SM-G960U using Tapatalk

Or ferment in a corny

Hmm... think of all the threads where a prospective beginner seeks advice on what kind of gear to buy.  We regularly tell them things like, make sure you get a big enough this or that, 15 gallon kettles, mash tun, electric whatever, BIAB, definitely temperature control right from the start -- wort chiller, ferm chamber... and with all this 21st century advice, get buckets or carboys, they're fine for a start.  Next time there's such a thread, maybe we should think of mentioning the need somehow  to deal with oxygen on the cold side (not touching on HSO here,) which we're all cognizant of now, unlike a few decades ago when the basic beginner's kit was set in stone.  It fits the same theme of "buy once cry once, retain resale value,  and develop good habits from the start."  Just a thought.

Ya know, I'd say that's way down the list of things a beginner needs to worry about.  And I'm not sure I really agree with the buy once, especially when one of the first things a beginner will use to ferment is a bucket.  They work fine and are inexpensive enough that they can be forgotten it the beginner wants to move on.  One thing that REALLY discourages beginners is being told they need a bunch of equipment when they don't even know if they'll stick with the hobby.

Fair enough.   I'm not about to tell them they need all this stuff and scare them off.  Just a lot of us eventually come up against this and put it in the "sure wish I knew about this earlier" file.  Just thinking a quick mention that it might be down the road could help a brewer setting up their first outfit decide how to allocate resources.  At least advising against glass carboys (evil things) is a start.

These are good points made by Rob and Denny.  Sometimes we forget that we are also here to help the new brewer make good beer using rudimentary equipment, which is how we all started.  Teaching them about the importance of sanitation and minimizing things that can effect the quality of their brews (like diacetyl and  techniques for oxygen minimization ideas expressed here) are the best way to keep them coming back. I believe in the K.I.S.S. principle (Keep  It Simple Stupid.....not the rock band).  I made some good beers in thee early days using an auto-syphon to transfer the beer between carboys and one of those silly bottling canes to bottle it from a bottling bucket.  As time went on we all became more advanced and can acquire new stuff to make our beers better.

[The Beerery]

[/quote

if it does it would be just a little vodka.

And oxygen.

Why is that, should have been co2 in the line at the start of the crash? Unless there is oxygen in the vodka, but like I said none made it to the fermenter.


O2 in the Vodka.

[brewsumore]

Why use an airlock when you cold crash?  Why not seal the carboy?  I know the standard answer is to prevent pressure from collapsing the carboy, but has anyone ever investigated whether that would really happen?  I'd guess there's not enough pressure.

I just replace the airlock with a small rubber stopper.  Done.  Occasionally, for an extended cold crash I will add a gas blanket of co2.

[Jeff Zesch]

Let me say first that I am not a chemist. When Robert posted something about surfactants I thought he was talking about a Beach Boys movie. 

I estimate that my 2 gallon (7.5 liter) headspace will shrink by 7% when cooled from 70 F (294 K) to 34 F (274 K). That is a volume of about 16 oz (500 ml), not a trivial amount. That air will mix in the headspace, exposing the beer to a 7% air mixture for days. Of course the exposure will be at a low temperature, so the chemical reactions will all be slower. There are other phases of the packaging process where the beer can be exposed to pure air but only for a few seconds or minutes. Which is worse: exposure to 7% air at 34F for days or exposure to 100% air at room temperature for seconds or minutes? I don't know, but my gut tells me that the longer exposure would more than compensate for the reduced temperature and concentration.

Using a rubber balloon should work, provided you put it on at the right time. Too early and it would overfill and explode or blow off. Too late and it would not collect enough CO2 and would collapse during the cold crash. Now I know that if that happens, though, I can just jiggle the carboy to release enough CO2 to partially inflate the balloon again. I will try that experiment on my next batch.

When you say "pure air" you are not talking about "pure oxygen".  Air in general is made up of about 78% Nitrogen, 21% Oxygen, .5% CO2 and the rest inert gasses. 

[Jeff Zesch]

Let me say first that I am not a chemist. When Robert posted something about surfactants I thought he was talking about a Beach Boys movie. 

I estimate that my 2 gallon (7.5 liter) headspace will shrink by 7% when cooled from 70 F (294 K) to 34 F (274 K). That is a volume of about 16 oz (500 ml), not a trivial amount. That air will mix in the headspace, exposing the beer to a 7% air mixture for days. Of course the exposure will be at a low temperature, so the chemical reactions will all be slower. There are other phases of the packaging process where the beer can be exposed to pure air but only for a few seconds or minutes. Which is worse: exposure to 7% air at 34F for days or exposure to 100% air at room temperature for seconds or minutes? I don't know, but my gut tells me that the longer exposure would more than compensate for the reduced temperature and concentration.

Using a rubber balloon should work, provided you put it on at the right time. Too early and it would overfill and explode or blow off. Too late and it would not collect enough CO2 and would collapse during the cold crash. Now I know that if that happens, though, I can just jiggle the carboy to release enough CO2 to partially inflate the balloon again. I will try that experiment on my next batch.

Your math is also way off.  As water (which is the majority of what beer is) cools from 20 degrees Celsius (70 degrees F) to 4 degrees Celsius (39 degrees F) it shrinks about .00021 ml per degree Celsius.  So the total shrinkage for 7.5 literrs will be about .0252 L or roughly .8 ounces.  No where near the full pint of liquid in your calculations.  Now as the water (or beer) is further cooled from 4 degrees C (39 degrees F) to 1 degree C (34 degrees F) it actually expands due to the unique properties of water that allows ice, a solid, to be less dense and float on top of water.

[Robert]

Let me say first that I am not a chemist. When Robert posted something about surfactants I thought he was talking about a Beach Boys movie. 

I estimate that my 2 gallon (7.5 liter) headspace will shrink by 7% when cooled from 70 F (294 K) to 34 F (274 K). That is a volume of about 16 oz (500 ml), not a trivial amount. That air will mix in the headspace, exposing the beer to a 7% air mixture for days. Of course the exposure will be at a low temperature, so the chemical reactions will all be slower. There are other phases of the packaging process where the beer can be exposed to pure air but only for a few seconds or minutes. Which is worse: exposure to 7% air at 34F for days or exposure to 100% air at room temperature for seconds or minutes? I don't know, but my gut tells me that the longer exposure would more than compensate for the reduced temperature and concentration.

Using a rubber balloon should work, provided you put it on at the right time. Too early and it would overfill and explode or blow off. Too late and it would not collect enough CO2 and would collapse during the cold crash. Now I know that if that happens, though, I can just jiggle the carboy to release enough CO2 to partially inflate the balloon again. I will try that experiment on my next batch.

Your math is also way off.  As water (which is the majority of what beer is) cools from 20 degrees Celsius (70 degrees F) to 4 degrees Celsius (39 degrees F) it shrinks about .00021 ml per degree Celsius.  So the total shrinkage for 7.5 literrs will be about .0252 L or roughly .8 ounces.  No where near the full pint of liquid in your calculations.  Now as the water (or beer) is further cooled from 4 degrees C (39 degrees F) to 1 degree C (34 degrees F) it actually expands due to the unique properties of water that allows ice, a solid, to be less dense and float on top of water.

The gas contracts too.  Not sure about the total volume involved, but I know from experience that crashing a closed fermenter from ~68°F to ~33°F results in a pressure drop of between 2-3 psig.   Which on a glass or plastic vessel could be quite dangerous.

[Richard]

Let me say first that I am not a chemist. When Robert posted something about surfactants I thought he was talking about a Beach Boys movie. 

I estimate that my 2 gallon (7.5 liter) headspace will shrink by 7% when cooled from 70 F (294 K) to 34 F (274 K). That is a volume of about 16 oz (500 ml), not a trivial amount. That air will mix in the headspace, exposing the beer to a 7% air mixture for days. Of course the exposure will be at a low temperature, so the chemical reactions will all be slower. There are other phases of the packaging process where the beer can be exposed to pure air but only for a few seconds or minutes. Which is worse: exposure to 7% air at 34F for days or exposure to 100% air at room temperature for seconds or minutes? I don't know, but my gut tells me that the longer exposure would more than compensate for the reduced temperature and concentration.

Using a rubber balloon should work, provided you put it on at the right time. Too early and it would overfill and explode or blow off. Too late and it would not collect enough CO2 and would collapse during the cold crash. Now I know that if that happens, though, I can just jiggle the carboy to release enough CO2 to partially inflate the balloon again. I will try that experiment on my next batch.

Your math is also way off.  As water (which is the majority of what beer is) cools from 20 degrees Celsius (70 degrees F) to 4 degrees Celsius (39 degrees F) it shrinks about .00021 ml per degree Celsius.  So the total shrinkage for 7.5 literrs will be about .0252 L or roughly .8 ounces.  No where near the full pint of liquid in your calculations.  Now as the water (or beer) is further cooled from 4 degrees C (39 degrees F) to 1 degree C (34 degrees F) it actually expands due to the unique properties of water that allows ice, a solid, to be less dense and float on top of water.

The gas contracts too.  Not sure about the total volume involved, but I know from experience that crashing a closed fermenter from ~68°F to ~33°F results in a pressure drop of between 2-3 psig.   Which on a glass or plastic vessel could be quite dangerous.

The volume calculation was based on the gas shrinkage alone, not the liquid, which I agree is negligible. I used the ideal gas law, PV=NRT, with P, N and R constant. That gives V1/T1 = V2/T2.

[Jeff Zesch]

Let me say first that I am not a chemist. When Robert posted something about surfactants I thought he was talking about a Beach Boys movie. 

I estimate that my 2 gallon (7.5 liter) headspace will shrink by 7% when cooled from 70 F (294 K) to 34 F (274 K). That is a volume of about 16 oz (500 ml), not a trivial amount. That air will mix in the headspace, exposing the beer to a 7% air mixture for days. Of course the exposure will be at a low temperature, so the chemical reactions will all be slower. There are other phases of the packaging process where the beer can be exposed to pure air but only for a few seconds or minutes. Which is worse: exposure to 7% air at 34F for days or exposure to 100% air at room temperature for seconds or minutes? I don't know, but my gut tells me that the longer exposure would more than compensate for the reduced temperature and concentration.

Using a rubber balloon should work, provided you put it on at the right time. Too early and it would overfill and explode or blow off. Too late and it would not collect enough CO2 and would collapse during the cold crash. Now I know that if that happens, though, I can just jiggle the carboy to release enough CO2 to partially inflate the balloon again. I will try that experiment on my next batch.

Your math is also way off.  As water (which is the majority of what beer is) cools from 20 degrees Celsius (70 degrees F) to 4 degrees Celsius (39 degrees F) it shrinks about .00021 ml per degree Celsius.  So the total shrinkage for 7.5 literrs will be about .0252 L or roughly .8 ounces.  No where near the full pint of liquid in your calculations.  Now as the water (or beer) is further cooled from 4 degrees C (39 degrees F) to 1 degree C (34 degrees F) it actually expands due to the unique properties of water that allows ice, a solid, to be less dense and float on top of water.

The gas contracts too.  Not sure about the total volume involved, but I know from experience that crashing a closed fermenter from ~68°F to ~33°F results in a pressure drop of between 2-3 psig.   Which on a glass or plastic vessel could be quite dangerous.

But in a fixed container, your volume remains constant.  If you are talking the gas only, the density of the gas will increase, but its volume will remain at the 2 gallons of head space that you started with.  You would have to calculate the change in density of air in order to figure out the additional oxygen exposure.  The difference in air density from 20 degrees C to 0 degrees C is 0.089 Kg/M3 or 0.089 Kg/1000L or 0.000089 Kg/L.  So in 7.5 L of head space, you get an additional 0.0006675 Kg of air.  Air being made up of only 21% oxygen, your additional oxygen exposure would be 0.000140175 Kg or only 0.140175 grams of O2.  Basically a negligible amount. 

A pressure drop of 2-3 psi is also negligible.  That change in pressure won't burst a glass carboy and will only affect the weakest, thin walled plastic ones.

[Richard]

But in a fixed container, your volume remains constant.  If you are talking the gas only, the density of the gas will increase, but its volume will remain at the 2 gallons of head space that you started with.

In a carboy open to the atmosphere the pressure remains constant. As the CO2 gas in the headspace cools it shrinks, and air is drawn in to keep the headspace volume filled at atmospheric pressure. The volume of air drawn in is equal to the volume shrinkage of the CO2 at constant pressure, about 500 ml.