Question about CFH - cubic foot per hour - on regulator

Bit the bullet and picked up a welder o2 bottle today, for aerating wort. I also picked up an argon regular(modded for o2), so I could really dial down the o2 to a reasonable amount.

Problem is that the flowmeter is not psi, but CFH - cubic foot per hour. Starts at 5 CFH and goes up to 40 CFH. I just can't figure out where to set it. Anyone have any experience with this?

The guys at the welding supply shop said to set it at 10. But, I would really like a little more confirmation on the right setting, and time to leave it on.

(I've heard that you can over oxygenate your wort. Is that true?)

Holy smokes, that sounds like a LOT of 02! I would start at the lowest for sure, but I have never seen this type of gauge. I guess if you have a diffusion stone, it may not matter. 5 minutes of o2 is usually enough for me.

4 CFH (assuming this is not SCFM) can be converted to L/min. According to the book "Yeast" by Chris White and Jamil Zainasheff, at 1 L/min for 1 minute, 20 L of wort (~5 Gallons) will be aerated to ~9.2 ppm O2.

So at 4 CFH * 1 hr/60 min * 28.3 L/ft3 = 1.87 L/min of O2

Run that for about 60 seconds through your wort and you'll be good. If it is SCFM, then you need to adjust for temperature. But you can still find out exact numbers with some calculations.

Hope this helps!

Thanks TheWall,

I was thinking about a minute on the lowest setting I could. I'll just play around and see what happens