Blow off Valve

[Ewalk02]

Are there any negative consequences to always using a blow off valve?? I set up my primary fermentor with a blow off tube going into a bucket of star san. It doesn't leak air around the tube so everything is going out into the star san solution and nothing is getting in. This is much easier than worrying if my fermentor is going to blow up due to a blocked air lock, so I've been using this technique for the last 3 beers.

 

[Moonpile]

We've been using a blowoff hose for just about everything. Just easier than cleaning up a mess.

 

[-Dan-]

No that's perfectly fine. Air looks (assuming you do a 5gal batch in a 5 gal carboy) always overflowing leaving a mess everywhere. Use a blow off tube in a bucket or large glass with some star san, etc. and you will be fine.
I don't know of any negative consequences ... somebody might correct me however

 

[batesjer]

I'm not sure but I think the OP means exclusively using a blowoff tube. Most people switch to an airlock after a few days because it is more convienent, but there is not harm in keeping the blowoff tube on througout the entire fermentation.

 

[cwhill]

Why a bucket of Star-San and not just water? Is there the possibility it will suck water back up?

 

[g_rath]

Paranoia. They are just being extra careful about sanitation. You could have a suck back but think it’s nearly impossible. The volume of air that would have to change in the carboy is huge.

 

[Moonpile]

Why a bucket of Star-San and not just water? Is there the possibility it will suck water back up?

We use Star-San in the bucket too, but mostly because we usually have some made up from sanitizing everything during the brew session. Also, it's less likely to develop mold or whatever in the bucket. Even if it did, it probably wouldn't hurt the beer, since the flow of gas and krausen is pretty much a one-way street, but who wants mold in their blowoff bucket?

 

[cwhill]

Thanks for the reply! Makes sense. Especially the mold issue! I put some in my bucket. One down side to it is my yeast is extremely active right now and those rapid yeasts bubble and the Star-San mixed make for LOTS of bubbles! Thanks again.

 

[CHunter]

I am brewing a lager and left the tube on it. When I lowered the temp for lagering, it sucked an entire jar full of funk back into the fermentor and ruined 5 gallons of brew that had just finished a 3 week fermentation!!! I am so pissed right now.

When you start to lower temps for lagering, always remove the tube.

 

[texashomer]

What causes blow off tube liquid to be sucked back into the fermenter? I've seen a couple of posts that mention something about a temperature change causing this and I had it happen this past winter. Does anyone know the mechanics behind this?

 

[atoughram]

Blow off valves are typically used to control compressor surge in turbo chargers...

 

[dyqik]

What causes blow off tube liquid to be sucked back into the fermenter? I've seen a couple of posts that mention something about a temperature change causing this and I had it happen this past winter. Does anyone know the mechanics behind this?

The pressure of gas in the headspace of the fermenter is proportional* to (absolute) temperature. Reduce the temperature and the pressure drops below atmospheric, sucking the liquid up the blow-off tube.



*Physicist's Pedantry Corner: actually, since CO2 dissolves better in the beer at lower temperatures, the pressure can drop faster than proportionally, as some of the CO2 moves to the beer. Also, the volume of the beer reduces as it contracts on cooling, reducing the pressure further. The contraction of the fermentation vessel is negligible.

 

[fixitoscar]

yup Suck back only really happens when you cold crash your fermentor.
The trick is to only have enough liquid to barely cover the bottom of your blow off tube. If it sucks back there isn't enough liquid to make it all the way up the tube and it will drop back down into your bucket.

 

[herc1354]

I am brewing a lager and left the tube on it. When I lowered the temp for lagering, it sucked an entire jar full of funk back into the fermentor and ruined 5 gallons of brew that had just finished a 3 week fermentation!!! I am so pissed right now.



When you start to lower temps for lagering, always remove the tube.

I've had this happen as well, although not to the extreme, since then I remove the blow off tube and hook up an airlock.


Sent from my iPad using Home Brew

 

[CHunter]

Many people recommend putting vodka into the airlock or blow off so if it gets sucked back in, it sucks in small amount of vodka instead of sanitary solution.