Makeshift Blow-off Tube


Posted by Nate

Saturday, August 28th, 2010

Last Update: August 30, 2010

My very first foam over occurred tonight, one day into primary for my Blackberry Wheat Ale. That meant I needed to get a blow-off tube made, and quickly. As it was 2 a.m. in the morning, I had to work with the supplied I had on hand.

The foam actually clogged the airlock and I had a bit of foam and beer come out around the edges of the lid, a first for me. I could see the lid bubbling around the edges, meaning that the lid really doesn’t have a good seal. I swapped the entire bucket/lid set for one I think will seal better (from #2 to #1). I poured the beer from one bucket to the other, so it was aerated nicely in the process.

I made a makeshift blow-off tube by attaching the drain-tube from my steam juicer to the airlock stem, and running that into a jar of water. It looked like it might work initially, video below:

The bubbling action in the above video doesn’t look too bad, and that is because a lot of the pressure wasn’t making it out the tube. The first blow-off tube has failed. It wasn’t releasing pressure quickly enough (I really need a bigger tube but its 2 a.m. in the morning so I have to work with what I have) so the lid kept popping open. I added 20 pounds of weights to the lid to help keep it on, and I revised the blow-off tube to be just the short tube directly from the bucket into a jar. This works much better and is keeping the lid on the bucket, though I need a longer tube so that I can have the water level in the jar lower, because I know that there will be foam-over on the jar after some time. You can see the real level of fermentation activity below. Notice how the weights drop slightly as pressure is released through the tube, pressure that was building up enough to lift the weights in the first place.

The next video shows the foam in the blow-off tube. You can see how it restricts the flow of gas and builds up pressure within the bucket. When the bucket has built up enough pressure it blows the foam through the tube and bubbles vigorously. Having that weight on the lid really helped force the built up pressure through the blow-off tube and not out the top of the bucket.


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