Temp reduction suckback - Let's brainstorm

[SpanishCastleAle]

I often put warm PBW in a glass carboy and seal it with a solid stopper and as it cools it pulls a vacuum. I dunno how much vacuum but the stopper is a bitch to get out sometimes.

Just saw this thread. Building upon your orig idea:
A carboy cap with short tubing connected to both 'ports'. One piece of tubing has a small inline valve. The tubing without the valve has a balloon connected. Let the end of fermentation fill the balloon (or you could do it manually) and if the balloon runs out of gas just hook up your CO2 to the inline valve and carefully refill the carboy and balloon with gas. The balloon would also act as a relief valve (more like a burst disk) to ensure you don't over-pressurize the carboy (even if you do burst the balloon, just keep a slow stream of gas flowing until you attach and fill another balloon).

Also, surgical gloves can work well instead of balloons depending on what you're 'connecting' them to.

 

[johnnybrew]

It might keep the liquid out of the fermenter but seriously, if you saw the inside of my fermentation freezer, you'd understand why I want to keep that air out of my fermenter.

Bobby - I didn't find this thread until someone gave me the link (see my new thread at https://www.homebrewtalk.com/f13/co...t-fluid-air-contaminating-181421/#post2099559). What was your final solution to this? Thanks.

 

[mojotele]

I've never had enough suck back to completely drain my airlock down to the point where air would get in.

But Yooper's suggestion seems simple enough. Or you could just clean your fermentation freezer, ya know

EDIT: I do find it kind of hilarious that nobody suggested cleaning the freezer up to this point (that I saw). And we're supposed to be a cleanly bunch!!

 

[Bobby_M]

Hexmonkey's diagram is what I planned to go with and I even have two PET containers with lids to do it. I just haven't rigged up the nipples yet. I realize it's probably a non issue but I like to find problems and obsess about them forever.

 

[dstar26t]

Bobby,
You could hook up a fixed liquid propane gas (LPG) regulator and CO2 tank to the fermenter. When serving cask ales on hand pump, the fixed LPG regulators are used to add CO2 as the beer is drawn out. I think the regulators are designed to apply .4 psi so it's not enough to push beer out of the hand pump and wouldn't be too much for a carboy. You'd only need it hooked up for 24 hours or so, long enough to crash the beer.
Nate

 

[944play]

Spunding valve. Done.

(...and a pressurizable fermenter, duh)

 

[hal2814]

You could just use a balloon.

 

[mithion]

+1 on using your normal airlock with vodka. Oxidation is non issue. People really need to quit over engineering everything...

 

[weirdboy]

I like the idea of racking to a purged keg and cold crashing in that. Then you can just hook it up and apply positive pressure with CO2 before you crack it.

 

[carrotmalt]

I like the idea of racking to a purged keg and cold crashing in that. Then you can just hook it up and apply positive pressure with CO2 before you crack it.

Are you saying to cold crash in the serving keg? Seems like that would defeat the purpose of the cold crash. I'm cold crashing a batch right now to get the suspended yeast and other debris to drop out so I can can then rack it to my serving keg nice and clean. (I'm under the assumption that "crack it" means serve it and not re-rack it to another keg.)

 

[ksbrain]

I have spent time worrying about this sort of thing, too. My concern was more the flavor of vodka being noticeable in a delicate beer. So I just calculated.

5.5 gallons=704 oz. At 5% ABV, that's about 35 oz. of alcohol.
Let's say you have one ounce of 80 proof vodka in the airlock. That's 0.4 oz. alcohol, which would amount to an extra 0.057% ABV in the batch.

Now I'm excited to cold crash something in the fermenter!

 

[Beer_Guy]

I like simple, so...

You could just use a long blow off tube with a several loops in it during fermentation and cold crashing. Just put a little Vodka or Starsan in the last loop. It would act as a large airlock and Co2 container.

With a large tube there should be enough volume so that by the time the temp quits dropping you’re still not getting any O2 in on the beer.

Since O2 will rise and there will be less turbulence in each progressive loop, the mixture of Co2 and O2 should decrease as it is sucked back through the loops.

(Forgive the quick drawing. I think it helps though.)

 

[weirdboy]

Are you saying to cold crash in the serving keg? Seems like that would defeat the purpose of the cold crash. I'm cold crashing a batch right now to get the suspended yeast and other debris to drop out so I can can then rack it to my serving keg nice and clean. (I'm under the assumption that "crack it" means serve it and not re-rack it to another keg.)

No, I'm saying cold crash in a keg, then rack to a serving keg. Although I'm pretty sure you could probably serve from the same keg if you shortened the dip tube a little.

 

[Fishin-Jay]

Once fermentation slows, sanitize a balloon (or unlubricated condom) and stretch it over the mouth of the carboy. The remaining CO2 produced as fermentation slows will fill the balloon and when you cool, the elasticity of the balloon will just allow the CO2 to flow back into the carboy. And, if cooling causes enough compression of the gas, the balloon/condom will just stretch into the carboy maintaining an airtight seal the whole time.

 

[hibbleton]

I'll be cold crashing for the first time soon and was thinking... since I'll be using a 3-piece airlock w/ Starsan, why not just put aluminum foil folded over top of the perforated lid of the airlock? So if the carboy starts sucking in the Starsan no (or not much) air can get in from the cooler because the foil will be pulled tight against the airlock. Seems like the simplest solution to me.

 

[johnnybrew]

I'll be cold crashing for the first time soon and was thinking... since I'll be using a 3-piece airlock w/ Starsan, why not just put aluminum foil folded over top of the perforated lid of the airlock? So if the carboy starts sucking in the Starsan no (or not much) air can get in from the cooler because the foil will be pulled tight against the airlock. Seems like the simplest solution to me.

hibbleton - I could be wrong, but don't think foil will hold a seal. I wouldn't count on it.

 

[Beer_Guy]

I did a simple test with a 3 piece air lock. They do work both ways. What happens is if you have a lot of fluid in them it gets pulled in. Once the level is down they are fine.

A cold crash will not draw air very fast or very long. So blow air slowly through the top before you insert it in the fermenter. Once you are not getting any fluid, you’re good.

 

[AnonyBrew]

Why didn't you tell me this before I bought my 17 other ferementers?

 

[jds]

Are you saying to cold crash in the serving keg? Seems like that would defeat the purpose of the cold crash. I'm cold crashing a batch right now to get the suspended yeast and other debris to drop out so I can can then rack it to my serving keg nice and clean. (I'm under the assumption that "crack it" means serve it and not re-rack it to another keg.)

I cold-crash in my serving keg regularly. After ~2 weeks in the fermenter, I rack to the serving keg, and put it in the fridge. 48 hours or so later, I add gelatin, and bump up the gas to carbonate. 24-48 hours later, I draw off the gunk in the bottom of the keg. The first pint or two has plenty of yeast sludge and gelatin goop in it, but afterward, it's clear sailing.

 

[crlova2]

What is the issue with just putting sanitized tin foil over the top and allowing a small amount of air to get sucked in when the temp drops. I don't have a dirty ferment chamber so is doing this a concern for infection?

 

[Beer_Guy]

…I don't have a dirty ferment chamber so is doing this a concern for infection?

Your call on that one.

I guess it depends on how anal you are and how big your fermenter is. The smaller the volume of brew the less shrinkage and the less air gets sucked back in during cold crash.

The original poster was concerned with liquid from the air lock AND oxygen being sucked in. He also sadly admitted …

…
My fermenting fridge isn't exactly a spotless sanctuary…

If oxidation rears its ugly head, then maybe rethink things. Until then if your fridge is fine just RDWHAHB.

Note: If I were concerned with bad guys, I might soak a clean rag in Star San and lay it over the foil on top.

 

[johnnybrew]

What is the issue with just putting sanitized tin foil over the top and allowing a small amount of air to get sucked in when the temp drops. I don't have a dirty ferment chamber so is doing this a concern for infection?

IMHO the concern is both infection from airborne microbes and exposing your beer to oxygen. I think the latter is a bigger cause for concern since it can cause an off-flavor (e.g., wet cardboard or sherry-like flavors) and is more of a guarantee (i.e., exposing your beer to O2 may not cause it to become infected, but you will definitely get some level of oxidation). Whether or not that small amount of O2 sitting on top of the beer in the fermenter will cause significant enough oxidation/off-flavors is not something I can comment on. For me, keeping O2 away from my beer is something I strive to achieve.

I think that infection is always something you want to keep vigilant about, especially if your beer is gonna sit in a bottle for many months at room temp. But, I am pretty anal retentive when it comes to sterile technique (I used to be a research scientist and worked with both human cell and bacterial cultures - both of which required meticulous technique).

 

[Beer_Guy]

Referring back to my earlier post, I still like my idea.

I realize the drawing may not be real good, but the idea is worth looking into. The coiled tubing needs only to be large enough to contain enough Co2 to refill the fermenter when it is chilled. It could be hung down the side of the fermenter, serve as an airlock during fermentation and be removed only at bottle time.

I have not done any cold crashing, but I have had some brew become oxidized so I WILL rig this up if I do.

 

[sigurdur]

Personally I like Hexmonkey's design. It is simple and very efficient.

As for having the pressure inside the fermenter less than the outside versus having your normal airlock system, consider this:
On a recent batch I smelled mold growing somewhere in the fridge. When I opened my plastic bucket to get a hydro sample, I found the mold. It was growing on the rim of bucket. (I must have been sloppy when taking a sample the last time)
Luckily it was not growing in my beer, however if there would be less pressure in the bucket than outside it, the suck-back effect would without a doubt suck mold in the fermenter.

 

[Soulrebel]

I think Bobby needs to get out the bucket, bleach and rag...Oh wait there is no fun in that. More gadgets, more gadgets!

 

[trigger]

In terms of simplicity, I'm sure that the large bore blow-off tube in starsan is the best solution, provided the reservoir (tube volume) is large enough. In a 6.5 gal carboy filled with 5 gal beer (large headspace) the gas will contract in accordance with Charles's Law, or V=k2*T, which can be re-written as V/T=k2, where V is the volume of the gas, T is the absolute temp, and k2 is some constant. Or:
P*V=n*R*T
=> V/T=n*R/P
Since n isn't changing (moles), R is a constant, and P in an open system will remain 1 atm (the weight of fluid drawn up will provide a slight decrease in pressure at the colder temps, increasing volume of the gas and in turn decreasing the amount of fluid drawn into the reservoir), n*R/P is a constant (k2). Plugging in numbers (cold crash after very warm ferment - max realistic volume change):

74 F = 23.33 C = 296.48 K
1.5 gal/296.48 K = 0.00506 gal/K
32 F = 0 C = 273.15 K
0.00506 gal/K*273.15 K = 1.382 gal
1.5 gal - 1.382 gal = 0.118 gal * 231 in^3/gal = 27.3 in^3

Volume of a cylinder (inside of a tube) is given by 3.14 * r^2 * L
for a 1" id blow off tube to achieve the desired volume you need:
27.3 in^3/(3.14 * (0.5 in)^2) = 34.8 in

This is the length of tube needed below the bend at the highest point to avoid drawing a siphon.

On a side note, I'm pretty sure that a nice long tube, even if left dry, so long as it remained below the level of the carboy mouth would prevent infection. In fact, Loius Pasteur proved this with his swan neck flask experiments on spontaneous generation. Placing the end of the tube in sanitized water woudl eliminate the CO2/O2 problem, though.

I'm pretty sure that the system with 2 2liter bottles is the best solution, though, as it's all sealed. You could even tape them together and use old racking canes for the dip tubes with little bits of leftover transfer hose for jumpers to make the whole thing more durable. Basically all you're doing is creating an extremely high volume airlock, so you could even use it all the way through and just purge it with new sanitizer each time you hook it on.

 

[jkreuze]

If you are getting airlock liquid sucked into the beer upon chilling then chilling is causing negative pressure. If you have negative pressure, you don't need to have an airlock on the fermentation vessel (airlock is for letting CO2 out without letting airborne baddies in).

So, can't you just stopper the vessel w/o airlock?

Might be a little tough to get the plug out if it is vacuumed in there, but sanitation shouldn't be an issue.

 

[trigger]

You could just bung the carboy, but yea, removal may get tough, not to mention the fireworks if the thing got warmed on accident. It would be like a 5 gallon can of Coors that got dropped. Granted it's not fully carbed, but that doesn't mean that the CO2 in there can't outgas. The idea was to create a system that allows the fermenter to remain at 1 atm, retains the sanitary conditions, doesn't let airlock water in, and keeps O2 out.

 

[RegionalChaos]

Cold crash in a sealed corny or serving keg, or do the sanitized foil open ferment.

 

[RegionalChaos]

In terms of simplicity, ...

74 F = 23.33 C = 296.48 K
1.5 gal/296.48 K = 0.00506 gal/K
32 F = 0 C = 273.15 K
0.00506 gal/K*273.15 K = 1.382 gal
1.5 gal - 1.382 gal = 0.118 gal * 231 in^3/gal = 27.3 in^3

Volume of a cylinder (inside of a tube) is given by 3.14 * r^2 * L
for a 1" id blow off tube to achieve the desired volume you need:
27.3 in^3/(3.14 * (0.5 in)^2) = 34.8 in

This is the length of tube needed below the bend at the highest point to avoid drawing a siphon.

...

I love this post! Fantastic. We should exchange beers.

:rockin::fro: