Oxygenate Wort- what PSI how long

I gave up my medical O2 tanks and regulator that read in CFM and got a 20Cubic foot O2 tank and a pressure regulator that measures PSI to aerate wort.
problem is I can't find any recommendations for PSI setting/duration to properly aerate wort, nor can I find a calculator online that will translate PSI to CFM.
I know there must be plenty of you who are using O2 from welding supply... how are you calculating your oxygenation?

You don't "convert" between the two.

Do you have any electrical experience?

Think of pressure as "voltage," mass flow (gas flow) as "current."

The flow rate is dependent on pressure AND resistance.

Put 20 psig on a 3 foot long, 1/16" diameter tube and on a 1 foot long, 1" diameter tube. How do you think the flow rates will compare?

Re-phrase the question, perhaps. (?)

Cheers

thanks for the response-
I understand there is no direct relationship between PSI and CFM- one is pressure the other is flow.
The 'medical' tank regulator I was using before metered the flow, but the regulator for the welding tank meters the outlet pressure.
What I am hoping to see is someone who is using O2 through an airstone who can suggest a PSI setting and duration through a reasonable length of 1/4 I.D. tubing ...say 4 ft... thru an airstone into 10Gallons of wort. I could probably get a ballpark CFM by blowing up a couple balloons with O2, but that still isn't telling me the most effective PSI to use and duration to get to a target range of oxygenation- say 15-17 PPM.
Also interested to hear if anyone using positive pressure O2 in a venturi is getting better efficiency than an airstone.
I don't brew enough to justify the meters to measure PPM of O2 but I am betting that someone out there is gonzo enough to have done it

I have just ordered this system:

http://www.williamsbrewing.com/BIG-OXYGEN-SYSTEM-P3426C106.aspx

They recommend 1/8 cfm for 1 minute. I don't know how similar or different your set up is, but it might be a starting point.

That regulator is similar to what I used on my medical oxygen tanks... it meters in CFM. I have a welding style regulator on my tank that measures the pressure (PSI) at the outlet, not the flow (CFM).
It sort of like the diference between measuring torque versus horsepower in a motor...

Lots of us just have the little regulator with no gauge on it, so we just turn the knob until bubbles just start to break the surface and let 'er run (through a diffusion stone) for about 20 sec for a 5 gal batch. Maybe some pros can chime in, but most of us just ballpark/eyeball it.

JonM said:

Lots of us just have the little regulator with no gauge on it, so we just turn the knob until bubbles just start to break the surface and let 'er run (through a diffusion stone) for about 20 sec for a 5 gal batch. Maybe some pros can chime in, but most of us just ballpark/eyeball it.

Click to expand...

+1 I just kinda eyeball the bubble flow to see a bunch of tiny bubbles instead of larger bubbles. Then I start "1 Mississippi, 2 Mississippi, 3 Mississippi.."

You will see different thoughts around how long to oxygenate. I usually do ~1 minute for a 5 gallon batch.

thanks.. that is my only option at the moment.
this stuff
http://www.tescom-europe.com/fileadmin/user_upload/Tescom_UK/Tescom_Common_Flow_Formulas.pdf

makes me want to stick pins in my eyeballs

yeah... Seems like a good place to apply the K.I.S.S. principle!

steveoc said:

I have just ordered this system:

http://www.williamsbrewing.com/BIG-OXYGEN-SYSTEM-P3426C106.aspx

They recommend 1/8 cfm for 1 minute. I don't know how similar or different your set up is, but it might be a starting point.

Click to expand...

I too believe in K.I.S.S., which is why I am returning the pressure regulator and have taken delivery on a 0-4 CFM regulator very similar to the Williams product
http://www.emergencyresponderproducts.com/cgoxre.html
for $24+ $6 shipping
I already have an airstone, although not the stainless steel wand type that Williams sells... and I think is quite nice, but not nice enough to make me replace what I already have.
and a 20cf oxygen tank that cost $77 to purchase and $15 to fill
http://www.weldingsuppliesfromioc.com/catalogsearch/result/?q=oxygen++cylinder+20+cf
all in all pretty happy with the results
but if you are starting from scratch, the Williams package is pretty good

Chris,

I've got a similar kit in the works, and my theory is this: Jamil and Chris W recommend 1lpm for 1 minute. So, I'm going to put a balloon in a 1L measuring cup with a lid on it, put the stone in the balloon, and fiddle until I figure out the regulator settings that work out to roughly 1lpm. Maybe that'll help you out.

Just noticed you returned the regulator. Ah well, leaving this info in case it helps someone else out

I was thinking of that too... but gas is funny stuff to quantify. I think the pressure of the ballon walls may compress the gas a bit so your reading wouldn't be an accurate representation of the amount of O2 at atmospheric pressure, but if there was an error it would be on the side of adding more O2 than needed... probably better than too little.
Also, i think there is a relationship between OG of the wort and optimal amount of oxygen, with higher gravity beers needing a higher PPM of O2.
1 liter (1LPM for 1 minute) may make sense at a specific quantity of wort at a specific gravity, but I don't know what quantity or gravity they were applying that recommendation to so its hard to extrapolate to the particular beer I might make.
Add to that the question of how much O2 is going into solution at a particular pressure (or flow rate) and it introduces yet another variable.
I was bummed to return the pressure regulator as it was - I think- a better quality device, but in the end I decided that there were so many variables involved with calculating O2 PPM in solution that I didn't need the other... apparently unquantifiable... variable of "pressure over time" versus "volume over time".
FWIW, I did feel the pressure of gas at the outlet for both regulators before I returned the pressure regulator. To Me, it seemed like 4CFM was pretty close to 2PSI. I wouldn't take that to the bank, but it may be a staring place for the ballon trial.
thanks, and good luck

Check out this guys findings.
http://www.homebrewersassociation.org/forum/index.php?topic=15595.0

Based on only ONE batch so far.... I used 6 psi for 60 sec. I'll try a little longer next time,, but based on the very quick start and strong yeast eating action .. I'd say what i did worked pretty good.

chrisdb said:

I too believe in K.I.S.S., which is why I am returning the pressure regulator and have taken delivery on a 0-4 CFM regulator very similar to the Williams product
http://www.emergencyresponderproducts.com/cgoxre.html
for $24+ $6 shipping

Click to expand...

That is pretty sweet. Before I bought my O2 regulator (cheapo from Harbor Freight Tools) I was looking for something like this but never found anything like it for non-medical tanks. Controlling O2 volume by pressure is very difficult and the typical pressures used for oxygenation are so low that most regulators aren't good at regulating them. You can drain a 20 cu ft in no time if you aren't on top of the pressure.

For the price this one is going on my Christmas list!

From everything I've seen, it would be very difficult--nearly impossible, in fact--to over-oxygenate your wort at pitching.

I go two minutes with pure oxygen at pitching through an 0.5 micron stone at a high enough rate to get a lot of action without excessive foaming. I often do the same thing about 12 hours after pitching for lagers, which tend to have a longer lag time.

Its impossible to calculate how much oxygen you are putting into the wort if you aren't doing it in a sealed vessel. There is no way to know how much is actually being absorbed into solution and how much is just floating away. 12PPM of oxygen for a 20L volume is only .24 mL. Thats not very much oxygen but that only works if you get 100% of it into the wort.

If you look at solubility of oxygen into fresh water, at 20C and 14.7psi you can get 6.8mL of o2 per L of water. Thats the max that is possible but that means keeping the liquid at a constant 14.7psi not putting 14.7psi into the wort and then letting some of it float away.

Basically, use a keg for a fermentor, pump 1-2psi o2 into it and let it sit until it reaches equilibrium.

that's interesting... how do you know when it has reached equilibrium?

osagedr said:

From everything I've seen, it would be very difficult--nearly impossible, in fact--to over-oxygenate your wort at pitching.

I go two minutes with pure oxygen at pitching through an 0.5 micron stone at a high enough rate to get a lot of action without excessive foaming. I often do the same thing about 12 hours after pitching for lagers, which tend to have a longer lag time.

Click to expand...

props to you- thanks for the help

chrisdb said:

that's interesting... how do you know when it has reached equilibrium?

Click to expand...

once it stops drawing in any oxygen. Its like force carbonating your beer. We have nice charts available that tell you what volume of CO2 you will end up with for a given pressure and temperature but I haven't been able to find the same for O2. Im going off of O2 saturation for water and extrapolating to find a volume effective for yeast. I would imagine that the higher specific gravity would make it a bit more difficult to get O2 into solution. In practically, i'd probably turn the O2 up to 5psi and shake the wort around for 30 seconds.

This also further contributes to the pros of fermenting under pressure. It just seems easier in the end. Dump your wort into a keg, pitch your yeast, pump some O2 into the sealed keg and shake it around, maybe do a quick purge to get the pressure just above atmosphere, then let her go. Use some CO2 or N2 to push from your primary to a secondary and there you have fully (or at least close) carbonated beer that hasnt touched air since brew day.

TheDecline said:

Its impossible to calculate how much oxygen you are putting into the wort if you aren't doing it in a sealed vessel. There is no way to know how much is actually being absorbed into solution and how much is just floating away. 12PPM of oxygen for a 20L volume is only .24 mL. Thats not very much oxygen but that only works if you get 100% of it into the wort.

If you look at solubility of oxygen into fresh water, at 20C and 14.7psi you can get 6.8mL of o2 per L of water. Thats the max that is possible but that means keeping the liquid at a constant 14.7psi not putting 14.7psi into the wort and then letting some of it float away.

Basically, use a keg for a fermentor, pump 1-2psi o2 into it and let it sit until it reaches equilibrium.

Click to expand...

I like where you are going with this- it could get you to a fixed volume and should conserve the O2 resources by containing it in the fermenter.
My fermenters aren't sealed like a keg, but I tested them with compressed air and they sealed well enough to hold a few pounds of positive pressure. Unfortunately, I let my pressure regulator go and replaced it with a flow regulator, but the flow regulator does stop flowing once it encounters back pressure equal to it's dispensing pressure.
I'll test the fermenter again with compressed air to get an idea of how much pressure they will hold and how quickly they leak down, and the next brew I will oxygenate into a sealed container using an airstone on a wand and hold the pressure until after the fermenter has leaked down.