Blowoff for 5G. Glass Carboy

I’ve read here and other sites stating that the correct OD for a blowoff hose for a 5 gallon class carboy is 1.25” but I wanted to relate a recent issue I had with using one.

I bought myself a 4’ section of 1.25” OD x 1” ID tubing from Home Depot and when I got home I tested it for air-tightness by inserting the tube in my carboy and blowing in the other end. Sure enough, no air leaked out from around the tube and as soon as I quit blowing the air rushed back out the end I was blowing in. Next batch of beer I brewed I attached the tube and it worked great. Once the blowoff was done I filled one of my ale pails with water and Oxyclean and dunked the tubing into it since it was rather cruddy.

When I pulled the tubing out of the ale pail I was a little concerned because the end of the tubing was no longer evenly rounded, it had been flattened on one side from being submerged in the ale pail. Sure enough, I insert the tube into my carboy and attempt the same test as above and air’s leaking out everywhere.

The problem, as far as I can tell, is that the 1.25” OD isn’t tight enough in the neck of the carboy for it to be forced back into a round shape when it’s inserted thus leaving a gap where the one side was flattened. Tonight I’m picking up a 1.5” OD tube and I’ll see how that works.

I just wanted to pass this experience on for all those who are debating what size blowoff to get.

I'll be interested to see how the 1.5" works. Our blowoff tube is a little flatter after being coiled up too. We've put saran wrap around the outside of the mouth of the carboy and the tube. It sealed a lot better.

my 6.5 gallon carboy is occupied and will need to use a 5 gallon primary for the brew I'm making on saturday. I've never used a blowoff tube and would also like to know about the 1.5" tube because I'm gonna be buying some tubing tomorrow. thanks.

I started using PVC blow-off tubes. They are cheaper than all 1.25 x 1" vinyl tubing, and you can take them apart to clean them. You still use about 6" of 1.25 x 1" vinyl tubing, but you use PVC pipe and elbows to make the 'bend' back down to the bucket, so no leakage problems.

There is a crummy picture in this post here. I got the idea from someone else on the board, and he had some really good photos. But I can't remember now who it was.

EDIT: Found a better photo in Brewiz's gallery here. But there are better ones out there still somewhere.

Well, I can't say whether a 1.5" OD tube will work because I can't find 1.5" tubing. The closest I can come is 1 and 5/8 and no, it doesn't work, too big.

However, I looked at the photos provided by FlyGuy and did some thinking and I think I have a setup for blowoffs that will work like a charm AND be easy to clean. I couldn't find a parts list for what FlyGuy showed pictures of but here's what I bought and it appears to work.

10' of 3/4" PVC
1' of 1.25"OD Tubing
4 3/4" PVC Elbows
A pair of PVC cutters, the ratcheting kind (This isn't necessary so to speak but a hacksaw leaves a much rougher edge.)

For my setup I cut a piece of the tubing off that was about 2" long. Then I cut three sections of PVC, 6", 10" and 22". Stick the 2" tubing on one end of the 6" piece, it's snug and you'll have to work at it but it will fit, and then shove that end into the carboy. For me, the fit was tight enough I could pick the carboy up by the 6" PVC. Connect the 10" to the 6" and the 22" to the 10" with the elbows and WHAM...you're done. Parts, including the cutter which was $12, cost me $17.

Thanks for the tip FlyGuy and I'm really looking forward to my double-brew day tomorrow.