** NOTE: Oxygenation equation updated based on data from dstar26t **
Does it seem like it’s hard to get all the information you need in one place? Since I just came down the learning curve on oxygenation, here’s what I hope is some valuable information.
You need to get oxygen into the wort for good fermentation (I assume most people know this). Splashing and sloshing is probably okay for low to medium gravities, but isn’t sufficient for high gravities, is not a very controlled process, and is hard to do with volumes greater than 5 gallons. If you want control and like high gravity beers (like I do) you need to aerate with oxygen.
General consensus is you need to be north of 8 ppm for standard gravities for medium gravity beers and north of 10-15 ppm for high gravity beers. Good references are Wyeast (http://www.wyeastlab.com/hb_oxygenation.cfm
) and Yeast book by White and Zainasheff.
If you’ve read along this far, you’re either ready to upgrade to an oxygenation system or upgrade your current system. A basic system which gets the job done, but isn’t controlled and can be expensive in the long run (by buying disposable, red oxygen canisters) is the William’s Brewing System (http://www.williamsbrewing.com/WILLI...STEM-P699.aspx
). I’ve used this system for a number of years and it’s served me well. However, I was never sure how much to open the valve and I always had to have extra tanks on hand never knowing when I might run out.
How do you control the process? Ideally you directly measure oxygen ppm (
- $169) and adjust your process from there. Whether or not you opt to buy a meter and take measurements, you can somewhat consistently control oxygen levels from flow rate. Here’s the equation assuming a 0.5 micron stone:
time = 0.113 * (volume / flow rate) * (ppm - 8.1019)
where “time” is oxygenation time in minutes, “ppm” is target parts per million (ppm) oxygenation, “volume” is volume of fermenter in gallons, and “flowrate” is oxygen flow rate in liters per minute (LPM). This is based on a couple data points from White and Zainasheff and a lot of data from dstar26t where they measured dissolved PPM after a known flowrate and aeration time. It's a rough equation which depends on things like wort temperature, wort density, and aeration method (in-line or submerged), but gets you close.
How to not run out of oxygen and control the process? Buy an industrial oxygen tank and regulator. The former is easy. Try any welding supply store or Airgas. Avoid medical oxygen tanks. They’re expensive, hard to find a place to fill, and use the same oxygen just in a fancier tank. The regulator is the tricky part. There’s lots of oxygen regulators out there (mostly medical) including on eBay. The problem is that most have a scale from 1 to 15 LPM. This is too coarse for fractions of LPM needed. The answer is a pediatric oxygen regulator. These are somewhat hard to find, but here’s the one I went with: http://www.respondo2.com/Pediatric_O2_Regulators.html
It was only $48, has a CGA 540 interface which is what most industrial oxygen tanks have, has a barb output, and has adjustable flow rate in 11 settings with as little as 0.03 LPM.
I hope that helps!! I scrounged the web for a while to both find a full equation for calculating flow rate and a suitable regulator that would have low enough flow rate.