How long will the small O2 tank last?

I'm going to get an O2 set-up for my higher gravity brews. Stone is on order, already have the other parts lying around the house. I am planning on using the small Bernzomatic cylinders. How many 5.5 gallon brews will this do - approximately?

a long time. Longer than you think. 2 mins for a 5 gal batch, and you'll probably get 12 batches out of it at least. I kept waiting for my first one to poop out and it went for forever.

I got looking at this article from BYO:

http://byo.com/mrwizard/1717.html

Which basically says that for a 5 gallon wort, you need 160 mg of O2 to add 8 ppm.

1ppm=1mg/L
5 gallons=20L
8 mg/L x 20L= 160mg O2 (.16 grams)

Those little tanks say 40.1 grams, so to add 8ppm per 5 gallon batch would be 251 batches. Can somebody see where I have gone wrong with this. Tweaked a bit (5.5 gallon normal batch at 85% retention of O2 = 203). This has to be wrong, right?

I put it on o2 for 2 to 5 minutes and usually get about 6 or 7 - 10 gallon batches.

Evan! said:

a long time. Longer than you think. 2 mins for a 5 gal batch, and you'll probably get 12 batches out of it at least. I kept waiting for my first one to poop out and it went for forever.

Click to expand...

Same with me. The thing keeps working and I have done at least 10 batches. I set it so the O2 just breaks the surface of the wort.

mr x said:

I got looking at this article from BYO:

http://byo.com/mrwizard/1717.html

Which basically says that for a 5 gallon wort, you need 160 mg of O2 to add 8 ppm.

1ppm=1mg/L
5 gallons=20L
8 mg/L x 20L= 160mg O2 (.16 grams)

Those little tanks say 40.1 grams, so to add 8ppm per 5 gallon batch would be 251 batches. Can somebody see where I have gone wrong with this. Tweaked a bit (5.5 gallon normal batch at 85% retention of O2 = 203). This has to be wrong, right?

Click to expand...

The numbers are right in theory but you'll lose a bit of oxygen as the bubbles break the surface. How much? No idea.

I am going to e-mail wyeast and see what they have to say about those numbers.

Wyeast says that you need to oxygenate for 1 minute to achieve 12 ppm which is ideal for a typical gravity brew.
http://www.wyeastlab.com/faqs.cfm?website=1#r46

Two minutes is fine, but it is unlikely that all that O2 is actually going to get used, unless you are pitching lots of yeast.

Yeah, I know what wyeast says, but something still isn't right AFAIC. The way I see it one of three things is going on here:

1. The absorption rate of O2 is incredibly low. I'm guessing an 80% average , but that's a pure guess.
2. People using a tank in 10-12 batches are over-oxygenating, or wasting a lot of their tank. 24ppm in 5.5 gal at 80% would yield 64 batches (if you can get all the O2 out of the tank)
3. Somebody's math is wrong.
4. A combination of all three.

I'd also like to know if that 12 ppm they calculate is in addition to the ambient ppm you will get from aerating the wort as it hits the carboy.

mr x said:

Yeah, I know what wyeast says, but something still isn't right AFAIC. The way I see it one of three things is going on here:

1. The absorption rate of O2 is incredibly low. I'm guessing an 80% average , but that's a pure guess.
2. People using a tank in 10-12 batches are over-oxygenating, or wasting a lot of their tank. 24ppm in 5.5 gal at 80% would yield 64 batches (if you can get all the O2 out of the tank)
3. Somebody's math is wrong.
4. A combination of all three.

I'd also like to know if that 12 ppm they calculate is in addition to the ambient ppm you will get from aerating the wort as it hits the carboy.

Click to expand...

I think a large amount of O2 is wasted, either through over-aeration or non-absorption. Even when I have the O2 flow on as low as I feel comfortable with, many bubbles make it to the surface and burst. If you could find a way to inject the O2 into the wort with minimal loss, then I am sure you could get many more than 12 batches out of a bottle. Homebrewers also don't know when to stop aerating because we can't measure the PPM.

Still, I'm not concerned. A bottle of O2 costs < $8. If I get 10 batches out of it I'm
spending $0.80 per batch. The peace of mind I get from knowing that I have enough O2 in my wort is worth it (especially for high gravity beers).

I've noticed that since I started using O2 my lag time is shorter, fermentation is more active, and attenuation is consistently higher than before for both AG and extract batches. These are improvements for me.

I think people will mistakenly run the O2 too fast because they're programmed to think a big frothy head on the beer is any indicator of dissolved oxygen. If you run it so slow that bubbles barely break the surface, you're wasting less for sure.

I've always heard people claim they get a shorter lag time with O2 but my experiments have always shown the contrary. However, both of my experiments have been with dry yeast, not liquid.

Another trick to make oxygenating more efficient is to gently rock/swirl the carboy as you add your O2. A lot less escapes this way and more gets into solution.