Blow-off tube recepticle re-think

[AlexBrew Senior Member Find all posts View Profile Close AlexBrew]

I only do blowoff tubes into a bottle while fermenting .. I had a thought about suckback when cold crashing. I submerge the tube into a bottle (or whatever) w saniteser or any liquid to prevent oxidation whilst controlling co2 expelsion from the fermentation. Now when cold rashing a negative pressure develops because of liquid shrinkage (assumed 4%) .. then problem being the liquid gets sucked uphill into the fermeter.

Read solution online is to put very little liquid into a bottle, then when sucktion happens there is not enough liquid to fill the tube and suction breaks and liquid goes back in bottle..

Right ..Rethunk method. Place the blowoff tube in a bottle with no liquid inside! co2 will expell whilst fermenting .. the whole system is co2 'sealed'. Now when cold crashing .. vacuume happens and co2 from te bottle will (should) go back upstream..
Now replacing the bottle w a 5litre empty water jug at the end of the blow off-tube. There should be enou co2 to feedback the vacuume of the liquid shrinkage .. right?

[AlexBrew Senior Member Find all posts View Profile Close AlexBrew]

^ grrr .. can't edit.
In my previous mssg .. I see I typed so fast that some characters couldn't keep up.

[jannieverjaar Senior Member Find all posts View Profile Close jannieverjaar]

That sounds awesome. 100% true. The co2 should sit there and get sucked back. Sounds like a good plan

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[BeerHolic Senior Member Find all posts View Profile Close BeerHolic]

Been using a wine stopper while cold crashing, since I started brewing 5 years ago.
Works like a charm

Stopper.jpg

[JIGSAW Senior Member Find all posts View Profile Close JIGSAW]

I just remove the tube and plug the whole with some foam.

KISS

[jannieverjaar Senior Member Find all posts View Profile Close jannieverjaar]

Tbh. There will be suckback. So if the bung or foam doesn't cause the sides to vacuum in you've introduced air. (But that o2 should be at the top and not on the beer.) BUT nr 2. there is the whole equilibrium/ dissociation discussion too. Although i think in this case gravity is the stronger force. The 5l bottle should at least reduce that o2. BUT it wont keep out the fruit flies

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[AlexBrew Senior Member Find all posts View Profile Close AlexBrew]

Been using a wine stopper while cold crashing, since I started brewing 5 years ago.
Works like a charm

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With this you mean to plug the end of the blowoff tube ?

[AlexBrew Senior Member Find all posts View Profile Close AlexBrew]

Tbh. There will be suckback. So if the bung or foam doesn't cause the sides to vacuum in you've introduced air. (But that o2 should be at the top and not on the beer.) BUT nr 2. there is the whole equilibrium/ dissociation discussion too. Although i think in this case gravity is the stronger force. The 5l bottle should at least reduce that o2. BUT it wont keep out the fruit flies

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It's inside the freezer .. but one could use insulation tape and block off the entrance of the bottle when the tube goes in. The bottle might shrink/crimple up a bit as the vacuum happens .. I saw a video where peeps do this with a balloon..

[BeerHolic Senior Member Find all posts View Profile Close BeerHolic]

With this you mean to plug the end of the blowoff tube ?

I do not use a blow off tube, I use a airlock.
When cold crashing I remove the airlock and plug the hole with a wine stopper.

Bubbler.jpg

[Dewald Posthumus Senior Member Find all posts View Profile Close Dewald Posthumus]

I use an airlock and cold crash with the airlock in place - never had any issues.

There's a layer of Co2 on top of the beer, the small amount of air that may or may not enter through the airlock will do nothing to the beer, the small amount of sanitiser that may or may not enter the beer via the airlock will not do anything to the beer.

I really don't understand what all the fuss is about.

[JIGSAW Senior Member Find all posts View Profile Close JIGSAW]

Verstaan jy

[Rocket-Boy Senior Member Find all posts View Profile Close Rocket-Boy]

I use a blowtie spunding valve which then feeds into a bottle of santiser.
Being under pressure it never sucks anything back at it goes from around 14psi at 20c to around 8psi at 2c.

[StevenD (Slainthe) Senior Member Find all posts View Profile Close StevenD (Slainthe)]

I use an airlock as well, for both normal fermentation and cold crashing. BUT, I fill it with vodka. As far as I'm concerned, anything that gets through that is okay with me.

As Jigsaw said, KISS is best.

Even when bottling, there is going to be a small amount of normal air that gets in while you are filling the bottles, but nothing substantial enough to affect the beer in the short term.

[AlexBrew Senior Member Find all posts View Profile Close AlexBrew]

My original post was about preventing sanitiser/liquid sanitiser suckback from the blowoff tube recipticle while cold crashing.

I know there are different techniques and methods that may work better - but blowoff tube is what I use.

So a discussion about suckback prevention is quite valid. Anyway, I listed 2 solutions in my original post which I will try and apply.

[Dewald Posthumus Senior Member Find all posts View Profile Close Dewald Posthumus]

Alex,

Just a question, do you really think that sanitiser suckback will suck all the way up past the bend and into the fermenter? Honest question, it seems like a lot of movement to me.