Question about Blowoff tubes

[Marko73]

Hey all,

I had sort of a technical question about blowoff tubes. Is the main purose to let built up air pressure release or krausen? or both?

The reason I ask is that I will be brewing the Big Ben Pale Ale this weekend from. I decided to upgrade to the Wyeast British Ale yeast so I will be making a starter. Although, the og is under 1.05, I am still expecting a vigorous fermentation and want to rig up a blowoff tube just in case.

My main question is that I have always used a 6.5 ale pail for my primary and I was going to rig a blowoff tube using an some extra bottling tubing I have trough the drilled hole on top. I also have a 5 gallon carboy and I am wondering if I need to use that with a larger diameter blowoff tube.

Will a blowoff tube rig in the ale pail be sifficient? I would rather use that as my primary and not rig up the carboy. .

Any thoughts?

 

[pizzaman]

The ale pail blowoff tube will work fine, it's all I've ever used, don't even own a single airlock. Just be sure the tube is long enough that your blowoff container can be sitting at a level below the pail to prevent nasty suckbacks. I see pics all the time with people's blowoff container sitting carelessly on top of their pails and shake my head.

 

[Whiskey]

I use 3/8 ID hose as a blow off, you just have to check it every-so often. I have had a near plug with it, that however that was a 5.75g in a 6 g Better Bottle, and the krausen actually ran into the tube and was bubbling out into the star-san container.

 

[BioBeing]

Is the main purose to let built up air pressure release or krausen? or both?

During a vigorous ferment, the krausen can rise up out of an airlock. This will cause a typical airlocks to clog, then there is no where for the CO2 that is being generated to go. Eventually, this will cause your lid or bung to get turned into a projectile, and a beer volcano will form all the way to your ceiling. Note that even your blow off tube can clog if it is too narrow, or gets kinked. I stick a piece of 1/2 inch ID tubing over the inner tube of my 3 piece airlock. [ETA - and cut the silly cross bit of the bottom of the airlock]

I used to use my 5 G carboy, but would lose too much beer! It needed a blow off every time. The same diameter tube should be OK - just make extra sure it doesn't clog/kink, because you will need it!

And don't worry about sitting the blow off bottle on top of the fermentor. With active fermentation, you are not going to get suck back unless the vessel suddenly freezes up. Just switch back to a regular airlock when fermentation slows.

 

[Arkador]

I use a blowoff for primary for every ale. First time i did an extract recipe with DME and a Hefewizen yeast, it was recomended to me by the lhbs, and I was glad to have it. I only switch to an airlock for secondary where there will be no kruzen.

 

[Minky]

And don't worry about sitting the blow off bottle on top of the fermentor. With active fermentation, you are not going to get suck back unless the vessel suddenly freezes up. Just switch back to a regular airlock when fermentation slows.

Suckback occurs when the temp in the fermentor drops and, like BioBeing says, won't happen during active fermentation...........BUT, if you pitch at a higher temp than the ambient air in your fermentation chamber, suckback could occur before the fermentation starts.

For example, if I want to ferment an ale at 66*, I will collect my wort at about 66* and place it in my fermenting chamber at about 61* or 62* covered with aluminum foil. Next morning, when things start bubbling, I put the blowoff hose in place.

 

[shoebag22]

what size tubing should I use for a 6.5 gallon glass carboy?

 

[BillTheSlink]

I couldn't tell you off the top of my head, but measure the inside diameter of your carboy neck hole then but a tube with the same outside diameter. When they sell tubing both ID and OD are on the box. You want a tight fit. soften the hose by placing it in hot water if necessary.

I always use blow offs. I never switch to an airlock most times unless it is going to sit in my room for a while.